Ajovy and Aimovig are both calcitonin gene-related peptide (CGRP) inhibitors used for migraine prevention in adults. The dosing, side effects, effectiveness and costs of these medicines can vary. As demonstrated in studies, these agents can reduce the number of migraine headache days you experience by about 1.5 to 3 days per month when compared to a placebo (inactive) treatment, but your response may vary.