The target is CGRP, a neuropeptide the sensory nerves around your brain release during every attack. It widens vessels and turns up pain signals. Inject CGRP into a migraineur and you trigger an attack; inject it into someone without migraine and nothing happens ¹. These drugs block it: four are monthly self-injections, two are pills.

Expect about two fewer migraine days a month than placebo, and a one-in-two shot at halving your monthly count. In the erenumab trial, treated patients dropped 3.7 days versus 1.8 on placebo, with 50% halving their attacks against 27% ². Galcanezumab and atogepant land in the same range ^{3 4}.

The average looks modest because it pools responders with non-responders. If you respond, your personal drop is closer to half your attacks. The effect holds for years ⁵.

This is a decision to bring to a neurologist. There is no head-to-head trial, so the pick comes down to delivery, insurance, and your other conditions.

The calendar shifts first. The self-injected drugs usually show within the first month and reach full effect by month three; the pills work inside a few weeks. Where you had ten migraine days you have five, and the ones you still get are often shorter or actually answer a triptan. The dread lifts before the frequency fully does — you start booking the trip you'd have cancelled. Fewer attacks also means fewer "migraine hangover" days lost to fog. It is not a cure: most responders go from frequent to occasional.

The real friction is cost and paperwork. List prices run near $800 a month, but commercial insurance plus a manufacturer copay card brings most patients to near zero. Most plans still require a prior-authorisation form showing four-plus migraine days a month and two failed older preventives; a first denial is the opening move, and a clean appeal usually clears ¹. Medicare patients pay specialty-tier prices.