WEDNESDAY, May 6, 2026 (HealthDay News) -- For chronic migraine, most calcitonin gene-related peptide (CGRP)-targeted therapies are probably effective for prophylaxis, according to a review published online May 5 in the Annals of Internal Medicine.Malahat Khalili, Ph.D., from the Michael G. DeGroote Institute for Pain Research and Care at McMaster University in Hamilton, Ontario, Canada, and colleagues explored the effectiveness and tolerability of pharmacologic prophylaxis for chronic migraine in a systematic review that included 43 randomized controlled trials and 14,725 participants.The researchers found high- and moderate-certainty evidence suggesting that eptinezumab, erenumab, fremanezumab, galcanezumab, and atogepant reduce monthly migraine headache days by two compared with placebo (mean difference, −2.34, −2.08, −1.77, −2.00, and −2.10, respectively). Monthly migraine days may be slightly reduced by botulinum toxin, while there is probably no effect for rimegepant. Compared with placebo, galcanezumab probably reduces dropout due to any cause (relative risk, 0.52). Discontinuation due to adverse events is probably increased with botulinum toxin (relative risk, 3.36). Few studies were found on topiramate, valproate, and propranolol, and those that were found had a high risk for bias."Evidence suggests that certain CGRP-targeted therapies (erenumab, fremanezumab, galcanezumab, eptinezumab, and atogepant) are probably effective for migraine prophylaxis; however, the conclusions are largely driven by industry-sponsored studies," the authors write. "Studies on older preventive options such as propranolol, valproate, fluoxetine, topiramate, and botulinum toxin had high risk of bias, limiting our ability to draw firm conclusions on their effectiveness, but these therapies may remain important alternatives where cost or policy restrictions limit newer treatments or for patients with certain comorbidities."Abstract/Full Text (subscription or payment may be required).Sign up for our weekly HealthDay newsletter