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Medically reviewed by Dr. Samuel Sarmiento, M.D., MPH on August 3, 2023

An open-label placebo alleviated seasonal allergy symptoms, whereas a conventional placebo had no effect.

Allergic rhinitis symptoms fluctuate with seasonal allergen levels. There is evidence that placebos are effective as symptomatic treatments. New research challenges the idea that placebo effects need deception by showing that open-label placebos (OLPs) can help patients with diverse clinical diseases. Due to the lack of blinding, more control tests are needed to test open-label placebos.

A study published in the journal Scientific Reports (a Nature journal) compared open-label with blinded placebos and treatment-as-usual (TAU).

Study Design and Population

This 2019–2021 randomized controlled trial included 89 seasonal allergy patients. Over 4 weeks, the researchers compared the effectiveness of an OLP to TAU and a double-blinded placebo. The DBP and OLP conditions required 30 drops three times a day. After 4 weeks, all subjects returned to a blinded researcher to complete allergy questionnaires.

Efficacy of an Open-Label Placebo Using Combined Symptom Questionnaire Scores

The OLP group improved more than the TAU and DBP groups in terms of scores on the Combined Symptoms and Medication Score (CSMS), a 12-hour and 2-week symptom assessment questionnaire. The Rhinitis Quality of Life Questionnaire (RQLQ) showed considerably greater improvements. The OLP group showed greater improvement than the TAU group on the CSMS over the last 2 weeks, with a medium effect size, but the last 12-hour comparison failed to reach significance.

Comparison of Nasal Symptom Questionnaire Scores With Open-Label Placebo Treatment

The OLP group outscored the DBP and TAU groups on the Total Nasal Symptoms Score (TNSS) questionnaire, as confirmed by TNSS scores for the last 2 weeks. However, this result was not statistically significant. OLP also outperformed the other treatments on the Rhinitis Quality of Life Questionnaire (RQLQ) and TNSS, with medium effect sizes. Nevertheless, participants did not report any statistically significant changes in their rate of nasal symptoms, as measured on the TNSS, during the past 2 weeks.

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Schaefer, M., Zimmermann, K., & Enck, P. (2023). A randomized controlled trial of effects of open-label placebo compared to double-blind placebo and treatment-as-usual on symptoms of allergic rhinitis. Scientific Reports, 13(1). https://doi.org/10.1038/s41598-023-34790-9