Entangled Illnesses: Embodied Experiences of Managing Multimorbidity

Multimorbidity, meaning multiple long-term conditions impacting a person's health, has become a rising societal and public health issue. The article contributes to the sociological study of chronic illness and multimorbidity by analysing how the blurriness of illnesses and entanglement of symptoms in multimorbidity is experienced and negotiated by people with coexisting chronic conditions. Drawing on qualitative interviews with people who live with endometriosis, fibromyalgia or hormonal migraine in Finland, we show how people with multiple chronic conditions distinguish between evolving symptoms based on past embodied experiences to make decisions about how to best manage their health. We argue that coexisting illnesses become entangled in ambiguous and open-ended ways, which, if left unaddressed, complicates treatment. Our analysis of illness experiences is aligned with the growing body of literature that argues that the single-disease model underlying healthcare systems fails to address the needs of patients living with multiple chronic conditions. Our emphasis on evolving entanglements between illnesses and the blurriness of conditions makes visible crucial discrepancies between lived illness and existing biomedical models and healthcare structures. 1 Introduction Following advances in biomedicine, many previously life-threatening diseases have become chronic, making ‘chronic living’ an important societal and medical issue (Wahlberg 2018). At the same time, multimorbidity—multiple long-term conditions impacting a person's health—has increased globally affecting ageing populations, as well as working-age and young people (Academy of Medical Sciences 2018; van Blarikom et al. 2023, 2024; Whitty and Watt 2020). In clinical practices, multimorbidity is addressed as a question of a patient's likelihood to develop other linked conditions, or as an issue that complicates the treatment of the coexisting conditions (e.g., Bardach and Schoenberg 2012; O'Brien et al. 2011). Epidemiology has mapped clusters of multimorbid conditions and identified affected population groups (e.g., Alshakhs et al. 2022; Mulick et al. 2022), whereas biomedical research has sought to locate biological mechanisms underlying multimorbidity (e.g., Fabrazzo et al. 2021; Sánchez-Valle and Valencia 2023). However, much is unknown about the biology of multimorbidity. A biomedical article exploring endometriosis—one of the illnesses that constitute the nexus of our study—notes that although endometriosis appears to be associated with inflammatory bowel diseases and autoimmune diseases, ‘it is still unclear whether a common endocrine, immune and inflammatory background predispose to the development of those conditions’ (Vannuccini et al. 2022, 340). The situation is similar with another illness central to our analysis: hormonal migraine. Although a type of hormonal migraine known as menstrual-related migraine has been associated with gynaecological conditions such as endometriosis (Calhoun and Ford 2008, 1191–1192), the precise biological mechanisms require further research (e.g., Adewuyi et al. 2020). Multimorbidity poses important questions also for the sociological study of chronic illness. Following Bury's (1982) influential work on chronic illness as ‘biographical disruption’, medical sociologists have examined how chronic conditions are lived with, and how social structures and personal experiences of illness shape one another (S. Bell, Tyrrell, and Phoenix 2017; Fang et al. 2023; Saunders 2017; Williams and Jones 2017). The rise of multimorbidity as a societal issue highlights the urgency of such questions. Social scientists have asked how multimorbidity is experienced by patients (e.g., Porter, Ong, and Sanders 2020; Sultan and Swinglehurst 2021; White, Lentin, and Farnworth 2016), how it impacts identities, social relations and sense of belonging (e.g., Pistulka et al. 2012; Potter 2024; Søndergaard, Reventlow, and Mogensen 2022), and how socioeconomic inequalities contribute to multimorbidity and to the ways its effects are felt (e.g., van Blarikom et al. 2024; Manderson and Warren 2016). Social scientists have also analysed the strategies of managing illness among people with multimorbid conditions as well as examined challenges in accessing healthcare services (e.g., Bosire 2021; Gallagher et al. 2013; Morris et al. 2011). Our article contributes to this growing body of sociological literature by exploring how people living with multiple chronic conditions negotiate the boundaries between their coexisting conditions. We analyse the ways in which illnesses become entangled in bodies affected by multiple chronic conditions, and how people with multimorbid conditions manage their treatment needs in healthcare systems centred on single diseases. Our approach is inspired by research that approaches intersecting chronic illnesses as enacted in situated practices. For example, Skovgaard and colleagues (2024) have shown how different versions of co-existing chronic illnesses are enacted in different clinical settings. In their case study, the ways in which breathlessness as a vague but potentially alarming symptom is evaluated during consecutive medical visits produces different sets of connections between symptoms and the patient's multiple illnesses. In a study of multiple chronic conditions among older adults, Porter, Ong and Sanders (2020) use a phenomenological approach that foregrounds lived embodied experience. They show how boundaries and links between illnesses are complicated by some conditions being ‘borderline’ illnesses. For example, lab results that are not quite yet at the diagnostic threshold may nevertheless constitute a health concern that complicates care. Crucially, centring embodied experiences of how chronic illnesses are entangled makes visible problems with the structures of health services designed for single diseases. In their exploration of multiple chronic conditions among working-age adults, van Blarikom, Fudge and Swinglehurst propose approaching ‘multimorbidity as an experience that manifests specifically from the mismatch between the way care services are organised and the way people experience their bodies in everyday life’ (van Blarikom et al. 2024, 3). In what follows, we ask how the embodied entanglement of multiple chronic illnesses is experienced and managed by people living with endometriosis, fibromyalgia or hormonal migraine, and at least another chronic condition. Severe persistent or recurring pain is a common symptom in these three conditions. Furthermore, each illness is gendered. Endometriosis is a gynaecological condition that affects around one in 10 women (Hudson 2022) as well as many trans and non-binary persons (Griffith 2020). Hormonal migraine is associated with shifts in oestrogen levels especially during the menstrual cycle (see Krause 2021). Fibromyalgia is considered feminised (Barker 2005): it is diagnosed almost exclusively in women even if women are only slightly more likely to satisfy the diagnostic criteria than men (see Wolfe et al. 2018). In this article, however, we focus on another aspect that cuts across these illnesses: their blurriness as medical conditions. The aetiology of these illnesses is not fully understood, and people with endometriosis, fibromyalgia and hormonal migraine often struggle to obtain diagnosis and treatment (Hudson 2022; Krause et al. 2021; Külekçioğlu 2022). These gaps in knowledge about the biological mechanisms underlying each illness affects how the entanglement of endometriosis, fibromyalgia or hormonal migraine with other illnesses is experienced. The analysis draws on interviews conducted as a part of a social science research project on gendered chronic illness in Finland. Our interlocutors include people who have more than one of these illnesses—for example, endometriosis and hormonal migraine—as well as people whose endometriosis, fibromyalgia or hormonal migraine intersects with some other chronic condition, such as irritable bowel syndrome, depression or asthma. The analysis we present is divided into two sections. The first analysis section centres on the role of embodied experiences in interpreting and acting on ambiguous and evolving symptoms of coexisting illnesses. The second one examines the ways in which the inseparability of entangled illnesses complicates treatment. We show that boundaries between entangled illnesses are enacted in relation to personal histories of treatment—including dismissal of symptoms by clinicians—as well as embodied knowledge of the shifting nature of one's symptoms. This emphasis on embodied experience makes visible crucial discrepancies between lived illness and existing biomedical models and healthcare structures. 2 Analytical Approach To study multimorbidity, we take the entanglement of illnesses as our analytical starting point. We analyse the ways in which chronic illnesses are intertwined and mould one another when people are living with multiple health conditions, and how these entanglements complicate treatment. We explore how people with multiple conditions draw distinctions between complex symptoms in order to negotiate the blurriness of illnesses and thereby manage their conditions. In other words, we approach the challenges of care arising from multimorbidity from the perspective of illnesses being entangled to the extent that it becomes difficult to recognise them as separate entities—which perhaps they never were. One influential approach that can be drawn on to theorise the multitude of illnesses is Mol's (2002) idea of multiplicity of single diseases. In the landmark work The Body Multiple, Mol (2002) formulates a strand of research that takes differences in medical practices as a starting point. Using atherosclerosis as an empirical case study, Mol argues that multiple ontologies of a disease are enacted when a patient's case is evaluated, treated and followed—for example, when a pathologist examines a tumour, or a patient performs physical exercise to alleviate pain caused by the medical condition. We suggest that this approach to ontological multiplicity provides important insights also into multimorbidity and the ways in which the boundaries and relations between entangled illnesses are enacted in situated practices. Mol contrasts her ‘playfully anti-philosophical way’ of using the term ontology (Mol 2002, 380) in the context of multiple enactments of single diseases in medical practices with sociological analyses of health and illness that set, for example, patient experience or professional perspectives at their core. Although we build on Mol's approach to illnesses as enacted in situated practices, we approach enactments of illnesses through patient experiences rather than clinical practices as such. In other words, we bring Mol's ontological approach and the sociology of chronic illness experiences into a productive dialogue. We contribute to theorising chronic illness by exploring how the multiplicity of multiple conditions is perceived and acted on by our interlocutors. We show that drawing connections and distinctions between illnesses enables them to react adequately to complex symptoms in order to mitigate symptoms when possible and to seek medical help when needed. In addition to tackling the interplay between multimorbidity, multiplicity and entanglement, our analysis is aligned with previous studies that take navigation as the analytical unit. Van Blarikom et al. (2023) have recently argued that the concept of social navigation can provide a useful means of approaching multimorbidity. They suggest that the framework of social navigation ‘can move us beyond attempts to pin down the concept [multimorbidity] through ever-more precise definitions and measurements’ (van Blarikom et al. 2023, 626). By focusing on social navigation, multimorbidity is no longer ‘a problem in a person's body’ but emerges ‘as an experience that exposes the limits of diagnostic categories and disease-based care’ (van Blarikom et al. 2023, 626). The point resonates with sociological studies of diagnosis, which have shown that diagnostic categories are socio-politically and historically shaped objects, and how they are mobilised shapes the ability of patients with complex symptoms to access care (A. V. Bell et al. 2024; Hauge 2024; Jeske, James, and Joyce 2024). In the context of our article, we understand navigation as a changing context-dependent set of strategies and practices that often draw on personal experience. We show that living with multimorbidity entails that the person resolves the multiplicity of illnesses by demarcating what symptoms belong to which condition. In addition, it entails caring for the self in consultation with different medical and non-medical sites that might be multiplied in the case of entangled illnesses. At the same time, experiences of failing to navigate the entanglements of symptoms or conflicts between disease-specific care recommendations make visible the inadequacy of existing healthcare systems in addressing multimorbidity. 3 Data and Methods Our data includes 69 interviews conducted in 2021–2023 in Finland: 27 with people with endometriosis, 21 with people with hormonal migraine and 21 with people with fibromyalgia. During the interviews, we learned that some of our interlocutors have more than one of these conditions; we have listed them above under the illness that provided the context for the interview. We found our interlocutors through a call for participants posted on the project's website and Twitter account and circulated through patient organisations' channels and word of mouth. We interviewed everyone who contacted us and had a diagnosis for endometriosis, migraine or fibromyalgia, and had received care in Finland. Our interlocutors have sought medical care for their chronic conditions across public and private healthcare services in different parts of the country, though not all are currently patients at any healthcare setting. Accordingly, we did not approach our interlocutors as ‘patients' but as experts on what it means to live with chronic illness in Finland. This collection of data also means that we cannot make claims about a specific clinical setting. However, as our interlocutors have faced challenges in accessing care across the healthcare system, it is likely that these challenges do not arise solely from localised clinical practices. Although our data provides an overview of experiences of living with endometriosis, fibromyalgia or hormonal migraine, it is not representative of people with these conditions. As our call was circulated online, the people who responded to the call are familiar with some digital technologies. Their ages range between 19 and 63 years; most are in their early twenties to late forties. As the interlocutors with endometriosis and hormonal migraine are fluent speakers of Finnish or Swedish, there is need for further study of how immigrants with endometriosis or hormonal migraine navigate the Finnish healthcare system. Although the call for endometriosis and hormonal migraine interview participants was open to everyone and not defined in terms of ‘women’, the gendered nature of these conditions means that interlocutors were assigned female at birth. The interviews on fibromyalgia were with a more diverse group of interlocutors: three were immigrants to Finland and more comfortable in English than in Finnish, and at least two of the interlocutors self-identified as cis-male at the time of interview. The focus on three gendered conditions means that our findings about multimorbidity are not necessarily applicable to all chronic conditions or population groups. The interviews on endometriosis were conducted by Oikkonen and Helosvuori, on fibromyalgia by Ganesh and on hormonal migraine by Rokkonen. The interviews took place either online or in person, depending on the interlocutor's location and, in some cases, their preference. Most of our interlocutors appeared comfortable using video conferencing tools, which we attribute to the familiarity of remote technologies since the start of the COVID-19 pandemic. Online interviews made it possible to include people who live in distant parts of the country and whose experiences usually remain invisible to those operating in the urban centres in the southern parts of Finland. The interviews lasted between 40 min and 2 hours. An audio file was transcribed verbatim either by a transcription company contracted by the university or by the author who had conducted the interview. The research follows carefully the Finnish National Board on Research Integrity (TENK) ethical guidelines for social science and humanities research. While the project sought and received a positive ethics committee evaluation for an ethnographic subproject conducted at an endometriosis clinic, interviews with consenting adults about their everyday experiences do not require external review according to the TENK guidelines. We received written informed consent from all interlocutors. The interlocutors were able to withdraw their consent and cancel their participation at any time. We also asked them if they wanted to clarify anything they had said during the interview or remove any details they had mentioned. We have taken special care to guarantee anonymity. We have removed mentions of location, profession or family relations that could reveal the interlocutors' identity. All names are pseudonyms. Each interview excerpt has been carefully reviewed by all four authors to make sure that it cannot be linked to other excerpts from the same interviews used in other research publications. As Finland is a small country, and some of the less common combinations of symptoms are shared by relatively few people, we err on the side of caution when giving contextual detail to make sure family members, friends or healthcare providers cannot recognise our interlocutors from the quotes. The interviews were semi-structured and covered a range of themes from the path to diagnosis to personal strategies of managing the condition as well as views of good care. While the interviews covered these themes, our interlocutors were able to focus on issues that they wished to explore and felt comfortable discussing. When we started the interviews, we were aware that endometriosis, fibromyalgia and migraine have been associated with each other as well as with other chronic conditions in multimorbidity literature (see Vannuccini et al. 2022). This led us to ask our interlocutors whether they had chronic conditions that affected the care of the first illness (‘first’ in the sense that the interview focused on that illness). What emerged from the interviews was a complex web of health conditions that shaped what kind of care was available. For example, our interlocutors reported how migraine with aura limits hormonal treatment options in endometriosis, and how a likeness between the symptoms of two coexisting illnesses may create uncertainty about which illness is causing the symptom. The complexity of these entanglements in our data suggested to us that a detailed analysis of the experiences of living with multiple entangled conditions is needed. The analysis was conducted jointly by the four authors and carried out manually. By engaging all authors through each step of the analysis, we sought to minimize subjective interpretation by an individual researcher. We narrowed our thematic focus by including only conditions that are chronic, leaving out acute conditions such as cancer or infections. We compared the three sets of interview data to identify patterns and differences. For example, we considered whether combinations of different chronic conditions are experienced differently and whether some entanglements of symptoms lead to specific difficulties when seeking care. We then organised these observations into two themes that structure the analysis sections: entangled symptoms and complications of treatment. However, the goal of the analysis is not systematic comparison. Instead, we focus on moments across the data when the symptoms of two or more illnesses become entangled or separated and the boundaries between illnesses become blurred or reinstituted. We pay special attention to the material and sociomedical contexts that structure such moments of entanglement and disentanglement as well as the effects on care that arise from such moments. 4 Entangled Symptoms Sometimes I have pain in different parts of the body, vague pain that comes and goes. There is no obvious reason why, unlike if someone had hit me, it just appears and then disappears. It can be in the arms, legs, stomach, head, neck. I’m not always sure, nerves and fascia and those. The symptoms can appear far from the sites where there is a problem. The pain is vague, wandering, but it can be intense. The way in which the pain appears in unexpected ways not linked to a specific condition makes it difficult for Aino to decide which illness is causing the pain. Among several of our interlocutors, experiences like these engender concern as to whether treatment or medical assessment is needed—and for which illness. Personal histories of living with pain contribute to the difficulty of distinguishing between pain related to different coexisting illnesses. Aino notes that getting used to pain over years has changed her sense of pain and has made it difficult for her to evaluate it: ‘The body has been exposed to chronic pain for so long that the pain mechanism is out of order’. Pain appears as an evolving embodied experience that gradually changes a person's way of interpreting symptoms (see also Helosvuori and Oikkonen 2024). Experiences of clinical encounters in which pain symptoms have been repeatedly dismissed—a form of ‘medical gaslighting’ (Sebring 2021)—also contribute to the difficulty of assessing the severity of one's pain. At the same time, personal histories of living with multiple conditions have made some of our interlocutors suspect that their illnesses might not be simply coexisting in the same body but could have an unconfirmed causal connection. Iina, who is in her mid-thirties and has endometriosis, asthma and migraine, wonders: ‘Is it just bad luck that I happen to have so many things [illnesses], or are they related’. Because the biomedical understanding of causative mechanisms of multimorbidity is often tentative, people with multiple chronic conditions rely on their own perception shaped by an embodied history of pain to make sense of how to draw connections and boundaries between illnesses. The role of personal histories of living with multiple illnesses is visible in the following example from Bea, in her forties. Bea has fibromyalgia and chronic fatigue syndrome (ME/CFS), two conditions whose symptoms are ‘characterised by greater similarities than differences’ (Sullivan, Smith, and Buchwald 2002, 887), and that lead to similar illness experiences, when occurring separately (Mckay et al. 2021). Bea notes: ‘I'm not even sure I can say anymore that I suffer because of fibro. My ME/CFS is so strong and has been getting worse because of all the ongoing flus’. Unlike Aino above, Bea has demarcated which aspects of her illness belong to fibromyalgia and which to chronic fatigue syndrome despite the purported similarities between the conditions. The history of living with both conditions has led her to construct boundaries between the illnesses. These boundaries involve embodied experience of what mediates the onset of the symptoms of each condition and how the resulting illness is felt. The need for such embodied boundary work is reinforced by the absence of clinical care that would take the complex links between the two conditions as the starting point of treatment. I have wondered if the migraine could have contributed to these panic and anxiety symptoms. Because now I have the strangest and most intense migraine attacks, they almost turn into panic attacks at some point. The symptoms are very similar, the heart races and I feel detached from reality. This also made me wonder if the panic symptoms that I had when younger were caused by migraine. For Tove, the similarity of migraine and anxiety symptoms suggests that one of the illnesses may have crossed what previously appeared to constitute a boundary between the two conditions, resulting in a blurring of illness boundaries. As in the previous examples, personal illness history plays a constitutive role in the evolving entanglement. Such experiences of migraine as evolving over time resonate with the biomedical finding that migraine can change its form through life (see Tietjen et al. 2010). At the same time, causal relations between physical and mental conditions may remain ambiguous. Jenni, in her mid-thirties, has identified anxiety and depression not only as coexisting illnesses but also as early symptoms of a forthcoming migraine attack: ‘I feel irritated, weak and that I'm good for nothing. That feeling results in migraine, not necessarily even in the same day, but it develops gradually, the feeling overwhelms, and in the end, it culminates in headache.’ These kinds of evolving illness boundaries do not fit easily within healthcare models centred on single diseases. When I get the migraine, I also get those old endometriosis pains. […] Usually when the migraine begins, my leg loses all feeling and I have pain around the vulva and the right side of my pelvis and I might lose control of my leg [when leaning on it]. There are signs of my long history of endometriosis pain in the migraine symptoms. This is an issue that [name of a neurologist], who knows hormonal migraine, this is all normal to them and they call it an aura. […] As these pains are ghostlike, it was a relief when [the neurologist] said that these things are connected. […] A doctor who understands what this is all about, that it’s normal that when you’ve had chronic pain for a long time your nerve pathways are activated. Here experience alone is ambiguous: the pain is described as ghost-like, following nerve pathways activated through years of living with endometriosis. Verification by a neurologist brings relief, allowing Lilja to draw distinctions as well as connections between the two illnesses. In the process, migraine ceases to be a part of the complex symptoms linked to menstruation (and thereby endometriosis) and has become an independent illness, much worse than earlier, and needs to be treated in its own right. While many of our interviews attest to the shortcomings of the single-disease model in healthcare, in Lilja's case a specialist provides crucial knowledge about the interconnections between illnesses that allows her to gain medical help as well as recognition. Another example about endometriosis and migraine highlights from a different viewpoint how the ontological status of an illness may change in patients' experience. Vilma, in her late thirties, describes how she had had occasional migraines in the past that had often coincided with her hormonal cycle. During the months before the surgical removal of her uterus and ovaries to treat endometriosis, she began to have intensifying migraine symptoms with aura. Unexpectedly, after the surgery, the migraine disappeared: ‘I had had migraine occasionally earlier, but not with aura. But it disappeared. After the surgery I have no longer had it. But it was a new symptom during the final months [before the surgery].’ The case raises questions whether an illness—in this case migraine—was an independent entity to begin with and what the link is between the illnesses. In both this and the previous excerpt, the entanglement of endometriosis and migraine is manifested in a concrete manner. While in Lilja's case the ghost of endometriosis pain became merged into migraine, for Vilma the unexpected disappearance of migraine after the surgery suggests that her migraine may have been linked to endometriosis all along. The removal of uterus and ovaries alleviates not only the illness that the operation targeted, but also another one entangled with it. The development of entangled illnesses over time also takes place in relation to different sites of the body. The way in which symptoms travel across the body makes it difficult to distinguish between illnesses and therefore to assess how to manage symptoms. A particular concern is symptoms in a ‘wrong’ (unexpected) place. Aino describes how her migraine appears as abdominal pain. During the abdominal migraine attack: ‘The intestine stops working. It feels like it pauses completely. I have constipation, everything stops. Then there's pain and it radiates from the lower back and stomach to the entire body.’ Importantly, Aino has experienced different types of abdominal pain caused by endometriosis and has also undergone gastrointestinal surgery. Instead of having to rely on medical descriptions of pain, she is able to distinguish between abdominal pain caused by endometriosis and abdominal pain caused by migraine based on embodied knowledge gained over years of chronic illness. My symptoms have recently evolved into abdominal visceral migraine. I can have intense stomach pain or an unpleasant feeling in the stomach or chest or around internal organs. They are very difficult attacks. I have started getting fast developing attacks that I feel acutely in the stomach, back and sides. In addition to pain, there’s pressure and sensations that are difficult to tolerate. I’ve been in disbelief that it really is still migraine. I’m afraid these could be heart symptoms, or stomach symptoms that could be gastrointestinal cancer, or I have a heart condition. But the symptoms are linked to the menstrual cycle. This description highlights the unpredictability of illness trajectories. The rarity of abdominal migraine and the entanglement of the symptoms makes Tove doubt her own bodily reactions. It also makes her worry whether the symptoms are normal for migraine or something more alarming, such as a heart condition. The fear is not unfounded, as cardiovascular diseases are known to be comorbid with migraine (see Sumelahti et al. 2021). The examples in this section have shown how mapping symptoms onto the multiple conditions one lives with is a challenging but ongoing task, and that medical models of treating chronic conditions may provide limited help. Instead, boundary-making is made possible by the personal histories of living with different conditions. Over time, such embodied histories allow people with multiple chronic illnesses to interpret how a condition tends to manifest, which kind of illness ensues and where across the body or mind it is felt. Even if the travelling of symptoms to other, ‘wrong’ parts of the body complicates this already difficult task, intimate knowledge emanating from a personal history of illness seems to overrule the confusion at times. However, boundary-making also challenges embodied self-knowledge by making some of our interlocutors ask whether what they experience now is a new face of something they have already experienced but had named differently. At the same time, experiences of chronic pain over years make some interlocutors doubt whether they can trust their sense of which symptoms matter. 5 Complications of Treatment The examples above show that people with coexisting chronic conditions tackle with experiences of ambiguous and evolving symptoms that do not fit within a single-disease framework. In this section, we turn to the challenges that people with multiple conditions face in accessing medical care and managing medications. The existing multimorbidity literature includes important analyses that show how the single-disease model underlying healthcare services may lead to dismissal or misdiagnosis of complex symptoms or inadequate evaluation of the effects of multiple medications (e.g., van Blarikom et al. 2024; Ecks 2021; Fudge and Swinglehurst 2022; Skovgaard et al. 2024). These challenges are visible also in our data: coexisting illnesses receive care at different clinical settings, clinicians do not communicate across these settings, and, as a result, the healthcare system cannot fully address the complications of care arising from multimorbidity. These challenges are present, for example, in the interview with Tove, who recalls visiting a doctor who said that they only take care of one illness at a time, even though the other health problem was a side effect of the migraine medication they had prescribed. Other interlocutors also describe difficulties they have encountered in getting a diagnostic test or a prescription for their complex health issues because such issues are considered to belong to another field of medicine or they fall between fields as, for example, in chronic pain without a clear underlying pathology. Several of our interlocutors describe situations in which a tension arises between the treatment needs of their coexisting illnesses. For example, intersecting conditions complicate what medications can be prescribed. In the simplest sense, this is a matter of one condition limiting the treatment options for another, such as hypertension or genetic risk of blood clotting limiting the choice of hormonal medications available for a person with endometriosis. Entangled illnesses may also result in interruptions or delays in care, as in the case for Kirppu, a young adult, who received a fibromyalgia diagnosis and initial pharmaceutical treatment while being suspected of having bipolar disorder. The diagnostic process of the latter entailed that Kirppu stop using all the medications that they had been prescribed. The treatment for fibromyalgia, including pain medication to manage flare-ups, was temporarily halted to satisfy the criteria for the assessment of an illness at a different medical speciality. Across our interviews, one issue complicating treatment is the work that managing multiple conditions requires from patients. As the previous section highlighted, people with coexisting chronic conditions put a lot of effort into negotiating the boundaries between illnesses. A specific concern for our interlocutors is how prescriptions and health information do not always travel between sites of care, and the patients need to make sure that each clinician is aware of their complex health histories, including contraindications for treatments. Elsa, who has endometriosis, depression and irritable bowel syndrome and is in her early thirties, notes that managing medications for multiple conditions is stressful: ‘You have to pay attention all the time because each doctor focuses on only one illness. I always read the package leaflet and I always ask at the pharmacy and so on. Sometimes it feels that I should hire a project manager to handle the medicines and treatments because there are so many.’ She describes an incident when she had been prescribed a strong pain medicine for her endometriosis and had discovered only at the pharmacy that it should not be used with the antidepressant she was taking. You put the pill straight under your tongue, it's really fast, and at first it worked really well. But then I started to develop all these sensitivities in my stomach, all of my senses exploded because there's aspartame in this medicine, it made me feel nauseous and that led to difficulties in eating, I noticed there's something new happening in my digestive system. After a while I started to experience breathing difficulties, I would wake up in the middle of the night to a sensation of not being able to breathe. Likewise Heli, who has migraine and asthma and is now in her sixties, mentions that the common asthma inhalers can cause headache as a side-effect, and for the migraineurs, the medicine can lead to an onset of a migraine attack. As with gastrointestinal symptoms, the situation is complicated by the fact that asthma and other respiratory illnesses are common comorbidities of migraine (Kim et al. 2023). This shows once again how the single-disease model fails to systematically address the needs of patients with multiple conditions even when those conditions are mapped as being commonly co-occurring. In endometriosis, hormonal products such as oral contraceptives are used to control hormonal levels, and in some cases, they may also alleviate the symptoms of other hormone-associated illnesses. However, several interlocutors consider that hormonal products they have used for endometriosis have contributed to the onset of hormonal migraine. Pilvi, who is in her mid-thirties, notes that her migraines had started when she began her first hormonal contraceptives, and now that she has come off the pill, she has been able to also discontinue her migraine medication: ‘It looks like my migraines were mostly hormonal after all. I haven't had to take preventive migraine medication or strong migraine medicines as I haven't taken hormones'. Iina, too, associates her past episodes of migraine with aura with a particular hormonal product. She notes that medical professionals seldom address the relationships between conditions and their treatments: ‘During my endometriosis treatment journey, I don't think anyone has ever asked about my migraine’. Treating multiple chronic illnesses is particularly tricky when it is ambiguous whether a symptom is a side effect of a medication or a part of an illness. Emilia, who is in her early thirties and has endometriosis, hormonal migraine and a thyroid condition, reflects on how it is ‘difficult to distinguish what causes what. When I feel unwell, is it because of this illness, is it because of this medication, is it because of another illness or its medications’. She notes that her body's responsiveness to even small doses of medication complicates treatment further. She draws a distinction between conditions that can be monitored easily through tests, such as her thyroid condition, and ones that cannot be captured as easily, such as endometriosis and pain: ‘The thyroid is simple, even though I respond strongly also to the thyroid medication [as to endometriosis medications], my experience is not questioned because it shows in the lab tests, they say wow how did that happen, you respond so strongly to such a small dose.’ Managing multiple entangled conditions, as the example suggests, is particularly difficult if the person's bodily response does not correspond to how bodies are expected to respond to biomedical interventions. Emilia relies on her own embodied sensations of symptoms and experiences of her body's past responses to medications to make sense of how symptoms and side-effects mould one another in her unique situation. The worst of all is if the endometriosis and migraine attacks come at the same time. They are both illnesses that react to stress, so when there’s some mental hardship in life, for example, one such situation was when my grandmother had a [life-threatening health emergency] […] After that both [endometriosis and migraine] hit. It meant that I lied on the bathroom floor and vomited and bled and my stomach hurt and my head hurt and my neck hurt and so on. And then if I get both, I can’t take pain medication because I throw it up. I have to first get the vomiting to stop with an injected anti-nausea drug, and then with the acute migraine attack medicine, so that I’ll be able to take the oral painkillers. Here two entangled illnesses respond to the same event. The intersecting diseases materialise through multiple levels of active embodiment—bleeding, vomiting, excruciating pain—that come into conflict in the treatment of pain. Despite the entanglement of bodily processes, Annukka resists the blurring of illness boundaries and constructs the two conditions as separate illnesses to manage them adequately. In this section, we have shown how people living with multimorbidity are made to take on the role of the carer in addition to the role of the patient to manage the complications arising from the entangledness of their illnesses. Due in part to the single-disease model of treatment, they are tasked with not only educating themselves on the crossover of their illnesses but also making sure that their clinicians are aware of issues such as drug interactions that could pose a threat to their health. In addition, medication prescribed to treat one illness can aggravate a comorbid condition, complicating the treatment path for the person embodying multimorbidity. A further complexity arises when multiple illnesses are triggered simultaneously but cannot be mitigated in the same way. Then, embodied history of living with multimorbidity may allow a person to navigate, through trial and error, how mitigation ought to be enacted, which can exacerbate distress in an already difficult situation. Bodies do not always respond to treatment in the ways they are generally expected to, which constitutes a further obstacle that pushes the person with multiple conditions to take an active role in evaluating the effects of treatment. All in all, our interlocutors express a strong wish that the healthcare system recognised and addressed the complex medical implications of the entangledness of their illnesses. 6 Conclusion We have explored how people living with endometriosis, hormonal migraine or fibromyalgia, and at least one other chronic condition, experience and manage the entanglement of their multiple conditions. We have shown how boundaries between different illnesses become blurred and reinstated, and how such entanglements are temporal by nature: the materiality of illnesses, their symptoms and relations to other illnesses unfold over time and through personal histories. The intertwinement of illnesses is manifested, for example, when they trigger each other's symptoms such as pain attacks, or take each other's shape through one illness appearing as a symptom of another. Our analysis of how the evolving entanglements of illnesses are felt and managed by people with multiple conditions contributes to the sociological literature on how societal structures, medical recognition and access to healthcare shape experiences of chronic illness. It also adds empirical insight on the lived complexities of multimorbidity to the growing social science literature on multimorbidity. We have shown that people affected by multiple health conditions make sense of their situation by differentiating between which symptom is caused by which condition. We argue that this differentiating takes place not only to understand the boundaries and connections between illnesses but also to navigate in a healthcare system that appears to lack structure to support managing multimorbidity. Drawing boundaries becomes a means to handle the complications of treatment that arise from the entangledness of illnesses. For many of our interlocutors, the relationship between their coexisting conditions is open-ended. As illnesses and their relationships evolve over time, our interlocutors re-evaluate their symptoms to understand how to treat the symptoms and when to seek medical advice. They also navigate questions such as which illness to treat first in acute situations and how to address the effects of medication on their other illnesses. Our research is in line with other studies showing how the single-disease model underlying healthcare services fails to address the needs of patients living with multiple conditions. Our focus on embodied experiences provides new insight on the uncertainties and ambiguities that people with multiple chronic conditions need to negotiate in managing their health. A special characteristic of illnesses such as endometriosis, hormonal migraine and fibromyalgia is their ‘blurriness’ as medical conditions. As noted above, previous studies have documented difficulties in diagnosing them. Our research shows that the blurriness of these conditions is heightened when they become entangled with other conditions, many of which have similar or overlapping symptoms. The healthcare system in which our interlocutors seek medical help appears as fragmented and often unable to provide adequate care. This forces patients to become their own carer in everyday situations. Furthermore, pain is characteristic of all three illnesses. Our data demonstrates that pain cannot easily be pinned down to one bodily site or illness: it crosses illness boundaries and can make distinguishing between illnesses difficult. Hence, future research is needed on how gaps in the medical understanding of mechanisms of pain affects the blurriness of chronic conditions and their lived entanglements. Mol's (2002) notion of ontological multiplicity of diseases has intrigued scholars to trace the multiple enactments of various diseases brought into being in particular ways in the medical practice. However, Mol's approach also invites us to explore how, instead of being fragmented, the body multiple ‘hangs together’ through coordination (Mol 2002, 55). We propose that the idea of entangled illnesses expands our understanding of the implications of enacting illnesses in medical practices. As noted, the current healthcare system is unable to handle appropriately the coordination work, which multiplies in the case of multimorbidity. Furthermore, the notion of entangled illnesses arising from lived experiences invites us to ask what it would mean for the medical practice to approach illnesses as not only affecting each other, but as entangled in the sense of lacking separate ontologies. The idea of social navigation (e.g., van Blarikom et al. 2023) that we draw from broadens the analysis into this direction by highlighting, through embodied experiences of our interlocutors, the limits of diagnostic categories and disease-based care. We suggest that the notion of entangled illnesses captures not only the medical enactments but also the lived intertwinements of coexisting conditions. Our findings suggest that multimorbidity makes a difficult situation in the healthcare system even more burdensome. Focusing on the entangledness of illnesses makes visible crucial discrepancies between lived illness and existing biomedical models and healthcare structures. At the same time, approaching entangled illnesses as something that is enacted in practices invites us to acknowledge that things could be done differently. We suggest that in envisioning better practices, a central role should be given to the embodied knowledge provided by people living with multimorbidity. Author Contributions Venla Oikkonen: writing–original draft (lead), writing–review & editing (lead), project administration (lead), funding acquisition (lead), conceptualization (equal), resources (equal), methodology (supporting). Elina Helosvuori: methodology (lead), conceptualization (equal), resources (equal), writing–original draft (supporting), writing–review & editing (supporting). Ahalya Ganesh: conceptualization (equal), resources (equal), writing–original draft (supporting), methodology (supporting), writing–review & editing (supporting). Lilli Aini Rokkonen: conceptualization (equal), resources (equal), writing–original draft (supporting), methodology (supporting), writing–review & editing (supporting).

We thank our interlocutors for their time and for generously sharing their experiences of living with endometriosis, fibromyalgia and hormonal migraine. Open access publishing facilitated by Tampereen yliopisto ja Tampereen ammattikorkeakoulu, as part of the Wiley - FinELib agreement. Ethics Statement The research follows the ethical guidelines of the Finnish National Board on Research Integrity for research in the humanities and social sciences. Consent We received written informed consent from all research participants. Conflicts of Interest The authors declare no conflicts of interest. Data Availability Statement The data are not publicly available due to privacy or ethical restrictions.