The minimum effective dose of abobotulinum toxin A injection for allergic rhinitis: A dose-escalation randomized controlled trial.

OBJECTIVE: To find the lowest effective injection dose of abobotulinum toxin A (Dysport) for allergic rhinitis. STUDY DESIGN: Dose-escalation randomized controlled trial. METHODS: We included all patients aged 18 years or older who had persistent allergic rhinitis and positive allergy skin prick test. The patients were randomly allocated to receive 40, 30, or 20 U of abobotulinum toxin A by injection at the inferior turbinate. We followed up on patients for 12 weeks to evaluate nasal symptoms, ocular symptoms, minimum nasal cross-sectional area as measured using acoustic rhinometry, and complications. RESULTS: Seventeen patients were included in this study, with 7 receiving 20 U of abobotulinum toxin A and 5 each receiving 30 U and 40 U. Abobotulinum toxin A significantly improved nasal congestion, rhinorrhea, sneezing, and loss of smell at 40 U (P < .05) and nasal congestion, sneezing, and loss of smell at 30 U (P < .05). However, at a dose of 20 U, only nasal congestion and loss of smell improved (P < .05). Nasal patency had also significantly improved two weeks after treatment at doses of 40 and 30 U (P < .05). Complications included epistaxis (11.8%) and nasal dryness (23.5%). CONCLUSION: Abobotulinum toxin A at a dose of at least 30 U effectively reduced most nasal symptoms. LEVEL OF EVIDENCE: 2. TRIAL REGISTRATION: Clinicaltrials.in.th/ TCTR20200526014.