Dietary habits of psoriatic patients treated with dimethyl fumarate and drug-related side effects: results from an observational study.

Background: Despite its favorable long-term safety profile, side effects during dimethyl fumarate (DMF) treatment for psoriasis are not uncommon and may lead to treatment suspension. The association between side effects, especially gastrointestinal, and dietary habits has not yet been specifically addressed.

Methods: This observational, cross-sectional study aimed to assess the dietary habits of patients with moderate-to-severe plaque psoriasis in treatment with DMF who attended three Italian psoriasis clinics. Demographic and clinical data, including any side effects, were collected from the patients' medical records. A self-administered questionnaire recorded and scored: 1) if meals are eaten regularly or not; 2) daily intake at meals of fatty foods, milk and dairy products, alcohol, fruit and vegetables; and 3) in the case of side effects, the time between eating and their onset.

Results: We included 53 patients in treatment with DMF at a daily dose of 232.4±194.1 mg for 38±29.8 weeks. Thirty-eight (71.7%) reported side effects, namely flushing (60.5%), diarrhea (44.7%), gastralgia (29%) and nausea (15.8%). Overweight seemed associated with the occurrence of side effects. In 47.4% of subjects, side effects appeared within 2 hours of having a meal. Daily fat intake appeared to protect against side effects, albeit without statistical significance; skipping meals was correlated with their onset in subjects complaining of diarrhea.

Conclusions: Finding some correlation between dietary habits and occurrence of side effects during DMF treatment requires further investigation with the aim of developing possible strategies to improve its tolerability and retention rate.