Efficacy and acceptability of dienogest among patients with endometriosis in Thailand

From April 2024 to May 2025, a total of 80 women with clinical endometriosis diagnosed by history, physical examinations, and ultrasound were assessed for eligibility at King Chulalongkorn Memorial Hospital, Bangkok, Thailand. Of these, 65 women who fulfilled the inclusion criteria were enrolled and analysis was performed in a total of 62 participants who completed the study (Fig.  1 ). The baseline characteristics of the participants are presented in Table  1 . The mean  ±  standard deviation ( SD) age was 34.2  ±  7.2 years. The mean body weight, height, and body mass index (BMI) were 57.5  ±  11.0 kg, 159.1  ±  5.8 cm, and 22.7 ± 3.7 kg/m², respectively. Dysmenorrhoea was the most frequently reported symptom, presented in 57 women (86.4%), followed by chronic pelvic pain in 40 women (60.6%). Twenty-two women (33.3%) were sexually active, and all reported dyspareunia. In addition, 15 women (22.7%) reported infertility, 12 women (18.2%) reported pain with defecation, and 5 women (7.6%) reported pain with urination. Fig. 1 Flow of the study Flow of the study Table 1 Baseline characteristics ( n  = 62) Variables Results Age (years) 34.2 ± 7.2 a Weight (kg) 57.5 ± 11.0 a Height (cm) 159.1 ± 5.8 a Body mass index (kg/m 2 ) 22.7 ± 3.9 a Dysmenorrhea 57 (86.4%) Non-cyclic pelvic pain 40 (60.6%) Sexually active participants 22 (33.3%) Dyspareunia in sexually active participants 22/22 (100%) Infertility 15 (22.7%) Pain with urination 5 (7.6%) Pain with defecation 12 (18.2%) VAS of Overall endometriosis associated pain 7.5 ± 1.5 VAS of Dysmenorrhoea 7.2 ± 2.0 VAS of Chronic pelvic pain 4.4 ± 2.8 VAS of Dyspareunia in sexually active women 5.2 ± 2.5 Baseline characteristics ( n  = 62) As a primary outcome, VAS scores for overall endometriosis-associated pain was statistically significant improved over a 24 week-period as assessed by Friedman’s test ( p  < 0.001). Moreover, VAS scores for dysmenorrhoea, chronic pelvic pain, and dyspareunia were also statistically significant improved over a 24 week-period, (all p  < 0.001). Data are presented in Table  2 . Table 2 Pain assessment at baseline, 12 weeks, and 24 weeks after treatment with dienogest Pain Characteristics At baseline At 12 weeks after treatment At 24 weeks after treatment p -value VAS of Overall endometriosis associated pain 7.5  ±  1.5 2.8  ±  2.2 1.9  ±  1.7 < 0.001 VAS of Dysmenorrhoea 7.3  ±  1.9 2.6  ±  2.3 1.9  ±  1.9 < 0.001 VAS of Chronic pelvic pain 4.5  ±  2.9 2.0  ±  1.7 1.6  ±  1.4 < 0.001 VAS of Dyspareunia 5.2  ±  2.5 2.1  ±  2.1 1.7  ±  1.8 < 0.001 Data were analyzed by Friedman’s test VAS Visual analog scale Pain assessment at baseline, 12 weeks, and 24 weeks after treatment with dienogest Data were analyzed by Friedman’s test VAS Visual analog scale The mean ( ±  SD) VAS score for endometriosis-associated pain decreased from 7.5  ±  1.5 at baseline to 2.8  ±  2.2 at 12 weeks and further to 1.9  ±  1.7 at 24 weeks of treatment. Pairwise comparisons demonstrated that the overall pain scores were significantly lower at both 12 and 24 weeks compared with baseline ( p  < 0.001 and p  < 0.001). However, overall endometriosis-associated pain scores between 12 and 24 weeks were not significantly different ( p  = 0.060). Data are presented in Table  3 ; Fig.  2 . Table 3 Pairwise comparisons of pain at baseline, 12 weeks, and 24 weeks after treatment with dienogest Pain Characteristics At baseline At 12 weeks after treatment At 24 weeks after treatment p -value compared to baseline p -value compared to baseline p -value compared to 12 weeks VAS of Overall endometriosis associated pain 7.5  ±  1.5 2.8  ±  2.2 < 0.001 1.9  ±  1.7 < 0.001 0.060 VAS of Dysmenorrhoea 7.3  ±  1.9 2.6  ±  2.3 < 0.001 1.9  ±  1.9 < 0.001 0.180 VAS of Chronic pelvic pain 4.5  ±  2.9 2.0  ±  1.7 < 0.001 1.6  ±  1.4 < 0.001 0.362 VAS of Dyspareunia 5.2  ±  2.5 2.1  ±  2.1 < 0.001 1.7  ±  1.8 < 0.001 1.000 Data were analyzed by Friedman’s two-way analysis of variance by ranks with Bonferroni correction VAS Visual analog scale Pairwise comparisons of pain at baseline, 12 weeks, and 24 weeks after treatment with dienogest Data were analyzed by Friedman’s two-way analysis of variance by ranks with Bonferroni correction VAS Visual analog scale Fig. 2 Assessment of endometriosis-associated pain outcomes at baseline, 12 weeks, and 24 weeks after treatment with dienogest Assessment of endometriosis-associated pain outcomes at baseline, 12 weeks, and 24 weeks after treatment with dienogest The mean ( ±  SD) VAS score for dysmenorrhoea decreased significantly from 7.3  ±  1.9 at baseline to 2.6  ±  2.3 at 12 weeks ( p  < 0.001) and 1.9  ±  1.9 at 24 weeks ( p  < 0.001). However, chronic pelvic pain scores between 12 and 24 weeks were not significantly different ( p  = 0.180). Data are presented in Table  3 ; Fig.  2 . The mean ( ±  SD) VAS score for chronic pelvic pain was 4.5  ±  2.9 at baseline. This decreased to 2.0  ±  1.7 at 12 weeks ( p  < 0.001) and 1.6  ±  1.4 at 24 weeks ( p  < 0.001). However, chronic pelvic pain scores between 12 and 24 weeks were not significantly different ( p  = 0.362) Data are presented in Table  3 ; Fig.  2 . The mean ( ±  SD) VAS score for dyspareunia decreased from 5.2  ±  2.4 at baseline to 2.1  ±  2.1 at 12 weeks ( p  < 0.001) and 1.7  ±  1.8 at 24 weeks ( p  < 0.001). However, dyspareunia scores between 12 and 24 weeks were not significantly different ( p  = 1.000). Data are presented in Table  3 ; Fig.  2 . Chronic disabling pain defined as self-assessment of pain which has persisted for three months or more and interferes with activities of daily life [ 32 ], were evaluated at baseline and 24 weeks after treatment. Twenty-six out of sixty-two women experienced chronic disabling pain at baseline. After treatment at 24 weeks, 25/26 women reported no chronic disabling pain ( p < 0.001). Data are presented in Table 4 . Table 4 Number of patients reported chronic disabling pain at baseline and 24 weeks after treatment At 24 weeks after treatment Baseline Yes No Sum Yes 1 25 26 No 0 36 34 Sum 1 61 62 p-value* < 0.001 Exploratory McNemar test was used for analysis Number of patients reported chronic disabling pain at baseline and 24 weeks after treatment Exploratory McNemar test was used for analysis Vaginal bleeding patterns varied following dienogest treatment. After 12 weeks, 17 women (27.4%) reported regular menstrual bleeding, 9 women (14.5%) experienced irregular bleeding, and 18 women (29.0%) reported spotting. Amenorrhoea was observed in 28 women (45.1%). At 24 weeks, the number of women with regular menstrual bleeding decreased to 12 (20.0%), while irregular bleeding and spotting were reported by 6 women (10.0%) and 13 women (21.7%), respectively. Prevalence of amenorrhoea increased from 28 women (45.1%) to 33 women (55.0%) at 24 weeks. (Table  5 ) Table 5 Vaginal bleeding patterns among participants at 12 weeks and 24 weeks after treatment At 12 weeks after treatment At 24 weeks after treatment p -value Regular menstrual bleeding 17 (27.4%) 12 (20.0%) 0.344 Irregular bleeding 9 (14.5%) 6 (10.0%) 0.549 Spotting 18 (29.0%) 13 (21.7%) 0.332 Amenorrhoea 28 (45.1%) 33 (55.0%) 0.263 Categorical data are shown in number(percent). McNemar test was used for analysis Vaginal bleeding patterns among participants at 12 weeks and 24 weeks after treatment Categorical data are shown in number(percent). McNemar test was used for analysis Patient-reported satisfaction score with treatment over time were measured using 0–10 satisfaction scale, with mean scores of 7.5 ± 1.9 at 12 weeks and 8.1 ± 1.5 at 24 weeks. These results are considered as satisfied in both time points. (Data are not shown) Additionally, none of participants reported using additional analgesic medications during the study period. Adverse events associated with dienogest treatment are presented in Table  6 . At 12 weeks, the most frequently reported adverse events were acne (19 women, 29.0%), depressed mood (10 women, 16.1%), and breast pain (9 women, 14.5%). Headache was also reported by 9 women (14.5%), while weight gain and hot flushes were less common, occurring in 6 (9.7%) and 3 women (4.8%), respectively. At 6 months, the frequency of weight gain increased to 16 women (26.7%), while acne remained common (16 women, 26.7%). In terms of body weight gain, the mean body weight increased by 3.1% (from 57.5  ±  11.0 kg to 59.3  ±  11.8 kg) with the mean BMI increased by 3.6% (from 22.7  ±  3.9 kg/m 2 to 23.5  ±  4.3 kg/m 2 ). Breast pain and headache were reported by 8 women (13.3%) and 6 women (10.0%), respectively. Depressed mood decreased to 6 women (10.0%), and no participant reported hot flushes at 24 weeks. Table 6 Adverse events of dienogest treatment ( n  = 62) At 12 weeks after treatment At 24 weeks after treatment p -value Weight gain 6 (9.7%) 16 (26.7%) 0.013 Acne 19 (29.0%) 16 (26.7%) 0.508 Breast pain 9 (14.5%) 8 (13.3%) 1.000 Headache 9 (14.5%) 6 (10.0%) 0.581 Hot flushes 3 (4.8%) 0 (0%) 0.500 Depressed mood 10 (16.1%) 6 (10.0%) 0.289 Categorical data are shown in number(percent). McNemar test was used for analysis Adverse events of dienogest treatment ( n  = 62) Categorical data are shown in number(percent). McNemar test was used for analysis

This was a single-arm, real-world prospective observational study conducted at King Chulalongkorn Memorial Hospital, Bangkok, Thailand, between April 2024 and May 2025. This study was approved by the Institutional Review Board of the Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand (IRB 427/66), reviewed by International Standard Randomised Controlled Trial Number (ISRCTN), and registration approval (ISRCTN68041248) on 13 March 2024. All the enrolled participants received information about the study, and written informed consent was obtained before the start of the study. All women aged 18–45 years presenting to the Gynaecology Clinic at King Chulalongkorn Memorial Hospital, Bangkok, Thailand, were screened for eligibility. Eligible participants were defined as women with at least one classical symptom of endometriosis-associated pain, including dysmenorrhoea, dyspareunia, chronic pelvic pain, or dyschezia, in the absence of other pelvic pathology as determined by history, physical examination, and transvaginal ultrasound. In addition, participants were required to have a Visual Analog Scale (VAS; 0–10) pain score of ≥ 4, with or without histological confirmation of endometriosis. All enrolled patients received dienogest 2 mg once daily for 24 weeks. The exclusion criteria were women with other identified causes of pelvic pain, a history of hysterectomy or bilateral oophorectomy, or those who were pregnant or breastfeeding. Women with contraindications to dienogest therapy (such as thromboembolic disease, severe hepatic impairment, or hormone-dependent malignancy), those who had received other hormonal treatments for endometriosis within the past 12 weeks or who were unable to provide informed consent were also excluded. The baseline demographic data were recorded before the initiation of dienogest treatment. A detailed history of endometriosis was obtained, including duration of symptoms, previous treatments, and any concomitant medication use. Pain severity was assessed using the VAS. All participants subsequently received oral dienogest 2 mg (Laboratorios León Farma, Spain) once daily for a total duration of 24 weeks. Follow-up visits were scheduled at 12 and 24 weeks after treatment initiation. At each follow-up, participants underwent reassessment of endometriosis-related pain using the VAS, as well as evaluation of any changes in symptoms and documentation of adverse events or additional medications. The primary outcome was the change in overall endometriosis-associated pelvic pain, measured by VAS between baseline and 6 months. The secondary outcomes included the changes in dysmenorrhea, chronic pelvic pain, dyspareunia, chronic disabling pain, at 24 weeks compared with baseline. The changes in overall endometriosis-associated pelvic pain and other pain symptoms between 12 weeks with baseline and 24 weeks were also assessed. In addition, adverse effects of dienogest were recorded at follow-up visits. All pain parameters in this study were evaluated by the VAS. VAS is a self-reported scale consisting of a horizontal line, with 10 cm long anchored at the extremes by 2 verbal descriptors referring to the pain status. The participants were asked to tick the line on the point that best refers to their pain [ 23 ]. Chronic disabling pain was assessed using a binary yes/no question. Overall endometriosis-associated pelvic pain is defined as participant’s overall perception of endometriosis-associated pain related to endometriosis and its impact on health assessed by participants [ 24 ]. Dysmenorrhoea in this study is defined as pain-associated with menstrual periods [ 25 ] without other identifiable causes. Chronic pelvic pain related to endometriosis in our study is defined as pain symptoms perceived to originate from pelvic organs/structures persisting for more than 6 months in the absence of other etiologies [ 26 ]. Dyschezia is pain during defecation [ 27 ]. Chronic disabling pain is defined as self-assessment of pain which persisting for three months or longer that interferes with daily life activities. Patient satisfaction score was assessed at 12 and 24 weeks after treatment initiation. A simple VAS was used to assess treatment satisfaction, scores on this scale were divided into three categories. Below a lower threshold of 4, it is shown that treatment should be considered inadequate and be modified, conversely, above an upper threshold of 7, it should be considered adequate and continued, and 4–7, no useful conclusion can be drawn [ 28 ]. Statistical analysis was performed using IBM SPSS 29.0 software (SPSS, Chicago, IL, USA). Descriptive statistics were used to present baseline characteristics and adverse effects. Non-normally distributed repeated-measures data were analysed using Friedman’s test. Post hoc pairwise comparisons following Friedman’s test were performed using Friedman’s two-way analysis of variance by ranks with Bonferroni correction. Nonparametric categorical data were analysed with McNemar test. The sample size in this study was calculated using the formula for two dependent means (two-tailed test) [ 29 , 30 ]. Based on data from previous study of dienogest [ 31 ], a standard deviation (SD) of 19 and a delta of 7 were used. An α level of 0.05 and a β level of 0.2 were used in the formula. The calculated sample size in this study was 60 participants. Considering a 10% dropout rate, the total sample size required for the study was 65 participants.

Our study demonstrated that dienogest treatment has significant improvements in all assessed pain characteristics, including overall endometriosis-associated pain, dysmenorrhoea, chronic pelvic pain, and dyspareunia between baseline and both follow-up timepoints. Beyond statistical significance, these findings are clinically meaningful, as the observed pain reduction translated into substantial symptom relief for participants. Disabling pain is one of the most important patient concerns, our study showed interesting result 25 out of 26 patients who reported chronic disabling pain at baseline, had significant improvement after treatment. Interestingly, none of the participants reported additional use of analgesic medications for the relief of endometriosis-associated pain during the study period. This finding cannot be fully explained. However, it may reflect cultural factors in Thailand, where individuals may have a higher tolerance for pain and are less likely to use pain-relieving medications unless they consider them necessary. Efficacy of dienogest treatment on endometriosis in our study was comparable to the results from Western countries [ 31 ]. These results showed efficacy and acceptability of dienogest for treatment of endometriosis across different genetics, geographies, and sociocultural context. A previous prospective Asian study also demonstrated that dienogest improved treatment outcome and patient quality of life over a longer-term, 24 month-follow up [ 15 ]. Comparable results were also observed in a recent multicenter Turkish study [ 33 ], which reported a significant decrease in both dysmenorrhoea and dyspareunia VAS scores, along with a reduction in endometrioma size during prolonged dienogest therapy. Due to both central and peripheral effects of dienogest, including inhibition of gonadotropin secretion, anti-inflammation, activation of apoptotic gene, and induction of amenorrhoea [ 18 , 34 – 36 ], the favorable treatment outcomes with this agent can be anticipated. In terms of dyspareunia, the improvements among sexually active participants were observed as early as 12 weeks after initiating dienogest treatment. By contrary, a study [ 14 ] evaluating sexual function using the Female Sexual Function Index (FSFI), found no significant improvement in the sexual pain domain at 12 weeks but rather at 24 weeks and beyond. Sexual function and dysfunction are complex and may arise from multiple contributing factors and closely linked with life events, burnout, workplace stress, and quality of life. Association between sexual dysfunction and quality of work was also demonstrated in previous study [ 37 ]. Hence, a comprehensive assessment of female sexual function using a biopsychosocial approach remains essential. Further studies are warranted to better elucidated the relationship between sexual function and endometriosis. A recent meta-analysis [ 38 ] demonstrated the efficacy of dienogest beyond placebo in postoperative medical management of endometriosis. In line with this, our study evaluated the efficacy and safety of dienogest in participants with and without a history of endometriotic surgery. The findings demonstrated the efficacy of dienogest as both an empirical treatment option and preventive therapy for disease recurrence following surgeries. Acceptability and satisfaction of endometriosis treatment are not solely determined by clinical efficacy. The frequency of adverse events and vaginal bleeding patterns are also important factors influencing patient perceptions and satisfaction. In our study, irregular bleeding was reported in 14.5% of participants at 3 months after treatment and decreasing to 10% at 24 weeks after treatment. Likewise, the prevalence of vaginal spotting declined from 29% at 12 weeks to 21.7% at 24 weeks. Although, the prevalence of abnormal vaginal bleeding pattern between 12 and 24 weeks were not significantly different. These downward trends in irregular bleeding and spotting highlight the need for appropriate counseling prior to initiating therapy, as these side effects are relatively common and should be counseled. Watchful waiting may be considered a reasonable approach, particularly in cases of mild bleeding. However, in patients experiencing severe vaginal bleeding, prompt and effective management should be performed [ 39 ]. International guideline on endometriosis management recommended that drug selection should be based primarily on clinical evidence based regarding efficacy, potential side effects, patient preference, cost, and drug availability. Hence, locally proven data on clinical efficacy and patient satisfaction are essential to guide decision-making for both physicians and healthcare policymaker. Economic difficulties remain one of the most important factors influencing treatment accessibility within healthcare payment system, particularly in Thailand, and other Southeast Asian countries. Treatment options with high efficacy, acceptable side effect profile, and high patient satisfaction score should be considered as a reasonable treatment option. However, our study was not designed to evaluate the cost-effectiveness of dienogest for endometriosis treatment in Thai context. To address this important issue, further well-design studies with cost-effectiveness analysis are warranted. No serious adverse effects were observed in our study. In terms of vaginal bleeding patterns, the outcomes were comparable to those reported in the Asian study [ 15 ], particularly regarding the prevalence of amenorrhoea, vaginal spotting and irregular bleeding at 6 months of dienogest use. Acne and depressed mood reported by participants in our study were assessed only through subjective questioning, without the use of standardized tools or validated questionnaires. Another study conducted in Asian countries [ 15 ] with longer follow-up period reported lower rate of acne and depression. Differences in the use of standardized assessment tools and in patient characteristics may have influenced the reported rates of adverse effects. Importantly, these adverse events were generally mild, showed a downward trend over time, and did not appear to significantly affect treatment adherence. Further research using validated instruments is warranted to more accurately evaluate the impact of dienogest on mood changes. Weight gain in our study has no specific cutoff for clinical significant. In addition, we did not employ specific parameters to assess body composition. Body weight is a complex parameter influenced by multiple factors, with hormonal use being one of the factors. In our cohort, the mean body weight increased slightly by 3.1% (from 57.5 ± 11.0 kg to 59.3 ± 11.8 kg), and the mean BMI increased by 3.6% (from 22.7 ± 3.9 kg/m 2 to 23.5 ± 4.3 kg/m 2 ). These changes did not reach the thresholds for obesity. These data should be further utilized for counseling patients for drug selection and prior to initiating treatment. Importanly, despite reports of acne, depressed mood, and weight gain, overall patient satisfaction remained high, and the discontinuation rate was low. In our study, nearly all patients completed the 24-week follow up, only three participants lost to follow up. The reasons of dropped out of the study including, transportation difficulties ( n = 1), intolerance to acne( n = 1), and intolerance to weight gain ( n = 1). Compared to another study [ 40 ], the dropout rate among dienogest users were similarly low, further supporting it favorable acceptability profile. In addition, patient satisfaction in our cohort was generally high [ 28 ], with mean scores of 7.5 ± 1.9 at 12 weeks and 8.1 ± 1.5 at 24 weeks., and acceptable adverse effects contributing to good overall satisfaction. When compared with GnRH agonists, dienogest demonstrates comparable efficacy in controlling endometriosis-associated pain, while being associated with fewer adverse effects. This favorable safety profile makes dienogest a more tolerable long-term treatment option [ 13 ], particularly for women who require sustained medical management. In addition, the oral route of administration and the absence of hypoestrogenic side effects further support its use as practical management in endometriosis. The strength of this study is its pragmatic, real-world design. Participant selection closely reflects routine clinical practice, as patients were diagnosed based on clinical assessment rather than surgical confirmation, enhancing the external validity and applicability of the findings to everyday clinical settings. Our study had several limitations. The absence of a control group is one of the major limitations, as it reduces the strength of the study’s conclusions, particularly in terms of comparing the efficacy and adverse effects of dienogest. Some reported adverse effects including, acne, weight gain and depressed mood in our study were assessed only through real-world subjective checklist, without the use of standardized tools or validated questionnaires. In addition, the relatively short follow-up period, and limited number of participants are another concern. Further well-controlled study with larger sample sizes, longer follow-up studies, other aspects of endometriosis related health, including quality of life, size of lesions are warranted to provide a more comprehensive understanding of the long-term efficacy and safety of dienogest. Additionally, the lack of histological confirmation for all participants may introduce heterogeneity and should be interpreted accordingly. The acceptability of dienogest were not assesed using a validated instrument. Instead, treatment acceptability in this study was indirectly evaluated through subjective assessment using a VAS.

Dienogest was associated with reducing pain and good satisfaction in Thai women with endometriosis, with an acceptable safety profile. These findings support its use as a practical long-term management option.

Endometriosis is a chronic, estrogen-dependent disease that affects 10–15% of women during their reproductive years. It is characterized by the presence of endometrial-like tissue outside the uterine cavity, which induces chronic inflammation, neovascularization, and fibrosis [ 1 , 2 ]. Although endometriosis was first described in 1861 by Rokitansky, it remains a complex and unresolved issue in medical research. The exact mechanism and pathogenesis of ectopic endometrial tissue implantation and progression remain under investigation. The clinical presentations of endometriosis widely vary among patients, including chronic pelvic pain, dysmenorrhoea, dyspareunia, dyschezia, impaired fertility, social relationships, and quality of life, which represent a significant burden on healthcare systems worldwide [ 1 , 3 , 4 ]. Clinical history, physical examination, and transvaginal ultrasound are the initial steps [ 5 ] in the diagnostic evaluation of endometriosis. Magnetic resonance imaging (MRI) may further enhance diagnostic accuracy by improving tissue characterization and aiding evaluation in symptomatic patients with negative transvaginal ultrasound findings [ 6 ]. Endometriosis could be considered as a chronic medical condition that requires lifelong management, surgical interventions should be considered as indicated and repeated surgical procedure should be cautious [ 7 ]. Hormonal therapies remain the mainstay of treatment for endometriosis-associated pain. Other approaches, including dietary and lifestyle modifications [ 8 ] as well as anti-inflammatory agents [ 9 , 10 ] and anti-oxidants, are currently being studied. The 2022 Endometriosis Guideline of the European Society of Human Reproduction and Embryology recommended hormone treatment as the mainstay of the management. Recommended options include progestins, combined oral contraceptive pills (COCs), gonadotropin-releasing hormone (GnRH) agonist and antagonist, levonorgestrel intrauterine system (LNG-IUS), and aromatase inhibitors. Progestins and COCs are considered as the first-line treatment for endometriosis, while second-line treatments include GnRH agonist and antagonist due to their side effects profile [ 11 ]. According to Asian consensus [ 12 ], dienogest and other progestins are preferred as first-line options for managing women with endometriosis. However, challenges in medical treatment selection include considerations of efficacy, cost, patient’s preference, and potential adverse events. Therefore, affordable pharmacological agents with proven clinical efficacy and satisfaction should be regarded as a reasonable option. Dienogest is a 19-nortestosterone derivative and a fourth-generation, orally active progestogen that exhibits highly selective binding to progesterone receptors, while demonstrating negligible binding for estrogen, androgen, glucocorticoid, and mineralocorticoid receptors [ 13 , 14 ]. Importantly, dienogest does not cause significant metabolic imbalance, and can be prescribed as a continuous regimen. Long-term investigations demonstrated that dienogest 2 mg administered once daily is well-tolerated and provides sustained benefits, including significant reduction in pain, improvement in quality of life, and enhanced sexual function after 6 and 12 months of therapy with stable efficacy maintained for up to 24 months [ 15 ] Evidence has further supported its comparable effectiveness to GnRH agonists in controlling endometriosis-associated pain symptoms [ 16 – 18 ]. On the other hand, COCs may present undesirable effects compared with progestins including dienogest [ 19 ]. Therefore, some experts recommended progestins over COCs for the treatment of endometriosis [ 19 ]. Dienogest has been shown to be significantly more effective than placebo in reducing endometriosis associated pain at 12 weeks of treatment. The most frequently reported adverse effects were headache (9.0%), breast discomfort (5.4%), depressed mood (5.1%), and acne (5.1%) [ 20 ]. Its efficacy and safety have been extensively evaluated in multiple studies, particularly in Western populations [ 20 ]. However, studies from Southeast Asia remain limited. Given that genetics [ 21 , 22 ] play some roles in pathogenesis of endometriosis, hence, treatment response, adverse events, and patient satisfaction may differ between Asian and Caucasian populations. In addition, sociocultural factors may further influence patients’ interpretation of symptoms and their reported satisfaction with treatment. Our study aimed to evaluate the efficacy, acceptability, and satisfaction of dienogest 2 mg (Endovelle ® , Laboratorios León Farma, Spain) in a Thai cohort, using a patient-reported questionnaire, with assessments at baseline, at 3 and 6 months of treatment. Thereby providing data that can inform Asian healthcare practices, policies, and contributing valuable insights to the field of endometriosis treatment in this region.