OnabotulinumtoxinA (BOTOX®): a guide to its use in preventing headaches in adults with chronic migraine.

Intramuscular onabotulinumtoxinA (onaBoNTA; BOTOX®) is indicated for headache prophylaxis in adults with chronic migraine. According to pooled results from two large trials, treatment with up to five cycles of onaBoNTA (155-195 units/cycle) at 12-week intervals was effective in reducing headache symptoms, decreasing headache-related disability and improving health-related quality of life in patients with chronic migraine. OnaBoNTA was generally well tolerated in these trials, with an adverse event profile that was consistent with that of the neurotoxin when injected into head and neck muscles.