Topical capsaicin for treatment of cannabis hyperemesis syndrome: a prospective observational study

Background: Cannabis hyperemesis syndrome is characterized by a classical cyclic pattern of recurrent nausea, vomiting and abdominal pain associated with a history of long-term cannabis use. Transient receptor potential vanilloid 1 receptors (TRPV1) appear to play an essential role. Topical capsaicin decreases cannabis hyperemesis syndrome symptoms by activating this pathway. We aimed to evaluate the effectiveness of topical capsaicin in reducing pain and nausea in emergency department patients with suspected CHS. Methods: In this single-center prospective, non-blinded, non-placebo controlled observational study, we treated patients suspected of cannabis hyperemesis syndrome with topical capsaicin. The primary endpoints were decreases in abdominal pain (ordinal pain score 0–10) and nausea (yes or no) after topical capsaicin. The emergency physician included patients based on self-reported use, information by companions, symptoms (abdominal pain, nausea and vomiting) and/or a positive urine toxicology screening result for cannabinoids at the OLVG hospital, Amsterdam. We excluded patients with an alternative diagnosis and patients who left the emergency department against medical advice. Patients who received other pain medication or anti-emetics were not excluded. Results: Abdominal pain declined from median ordinal pain score of 8 at arrival to 2 at discharge, and 67% of patients achieved an acceptable level (ordinal pain score < 4) after application of topical capsaicin. Vomiting stopped in 50% of patients after topical capsaicin application. Conclusion: Capsaicin is feasible, safe, and effective in reducing nausea and abdominal pain in patients with cannabis hyperemesis syndrome. We recommend capsaicin administration in patients with suspected cannabis hyperemesis syndrome.