Remotely provided open-label placebo reduces frequency of and impairment by allergic symptoms

Background and Objective: Placebos being prescribed with full honesty and disclosure (i.e., open-label placebo = OLP) have been shown to reduce symptom burden in a variety of conditions. With regard to allergic rhinits, previous research provided inconclusive evidence for the effects of OLP, possibly related to a separate focus on either symptom severity or symptom frequency. Overcoming this limitation of previous research, the present study aimed to examine the effects of OLP on both the severity and frequency of allergic symptoms. Methods: In a randomized-controlled trial, patients with allergic rhinits (N=74) were randomized to OLP or treatment as usual (TAU). Due to the COVID-19 pandemic, OLP was administered remotely in a virtual clinical encounter. Participants took placebo tablets for 14 days. The primary outcomes were the severity and frequency of allergic symptoms. The secondary endpoint was allergy-related impairment. Results: OLP did not significantly improve symptom severity over TAU, F(1, 71) = 3.280, p = .074, ɳ²p = .044, but did reduce symptom frequency, F(1, 71) = 7.272, p = .009, ɳ²p = .093, and allergy-related impairment more than TAU, F(1, 71) = 6.445, p = .013, ɳ²p = .083, reflecting medium to large effects. The use of other anti-allergic medication did not influence the results. Conclusions: While OLP was able to lower the frequency of allergic symptoms and allergy-related impairment substantially, its effects on symptom severity were weaker. The remote provision of OLP suggests that physical contact between patients and providers might not be necessary for OLP to work.