Calcitonin Gene-Related Peptide Medications: How CGRP Drugs Work

Calcitonin gene-related peptide (CGRP) medications are prescription drugs that block CGRP or its receptor to prevent and treat migraine. The FDA has approved two families in the United States: monoclonal antibodies given by injection or infusion for prevention, and gepants taken as a tablet or nasal spray for both prevention and acute treatment. They are the first migraine drugs designed around migraine biology rather than borrowed from other conditions.

What Is Calcitonin Gene-Related Peptide?

CGRP is a 37-amino-acid neuropeptide that the trigeminal nerve releases during a migraine attack. Levels of CGRP rise in the blood draining the head during migraine, and infusing CGRP into people who get migraines can trigger a migraine-like headache.

That makes CGRP a clean target: block the peptide or its receptor, and the pain-signaling cascade weakens. CGRP is unrelated to parathyroid related peptide, which regulates calcium and bone metabolism. The similar names cause confusion, but the two molecules do very different jobs.

The Two Classes of CGRP Medications Compared

The size difference between the two classes explains the dosing. Antibodies are large proteins that stay in the body for weeks, while gepants are small molecules that clear within hours.

CGRP Monoclonal Antibodies for Prevention

All four antibodies are given on a monthly or quarterly schedule, and three of them can be self-injected at home.

• Erenumab (Aimovig): 70 mg or 140 mg self-injected once a month.
• Fremanezumab (Ajovy): 225 mg monthly, or 675 mg as three injections every three months.
• Galcanezumab (Emgality): 240 mg loading dose, then 120 mg monthly.
• Eptinezumab (Vyepti): 100 mg or 300 mg IV infusion every three months, given in a clinic.

Erenumab became the first CGRP medication approved in the United States, in 2018. Galcanezumab is also FDA-approved for episodic cluster headache, which responds poorly to most other treatments.

Gepants: Pills and a Nasal Spray

Gepants are taken by mouth or sprayed into the nose, so they work well for on-demand use at the first sign of an attack.

• Ubrogepant (Ubrelvy): 50 mg or 100 mg at migraine onset; a second dose may be taken two hours later.
• Rimegepant (Nurtec ODT): 75 mg that dissolves on the tongue, taken as needed for attacks or every other day for prevention.
• Zavegepant (Zavzpret): 10 mg nasal spray for acute treatment.
• Atogepant (Qulipta): 10 mg, 30 mg, or 60 mg once daily for prevention.

How Well Do CGRP Medications Work?

In clinical trials, roughly 40% to 50% of people who take a CGRP monoclonal antibody for prevention cut their monthly migraine days by at least half. Response varies: some people improve within the first month, while others need two to three months before the benefit is clear.

For acute treatment, gepants leave about one in five people pain-free at two hours, compared with about one in ten on placebo. CGRP medications reduce migraine frequency and severity rather than eliminating migraine entirely.

The American Headache Society lists CGRP monoclonal antibodies as a first-line option for migraine prevention, alongside older drugs such as beta-blockers and topiramate.

Side Effects, Safety, and Who Should Avoid Them

• Monoclonal antibodies: injection-site redness or pain is the most common complaint; constipation and, rarely, rising blood pressure have been reported with erenumab.
• Gepants: nausea, drowsiness, and dry mouth are typical; the zavegepant nasal spray can leave a bitter taste.
• Drug interactions: gepants are broken down by the CYP3A4 enzyme, so doses may need adjusting with strong inhibitors or inducers.
• Pregnancy: data are limited, and most guidelines advise avoiding CGRP medications during pregnancy unless a specialist decides the benefit clearly outweighs the risk.

Calcitonin gene-related peptide medications are FDA-approved for migraine and, in one case, episodic cluster headache. They are not approved for tension-type headache or as general pain relievers, so a clinician should confirm the diagnosis before prescribing them. Unlike triptans and NSAIDs, gepants have not been associated with medication overuse headache in trials.

Cost and Insurance in the United States

List prices for CGRP medications generally run from about $600 to more than $1,000 per month before insurance. Most commercial plans require prior authorization and documentation that two or more older preventive drugs failed or caused side effects.

Manufacturer copay programs often lower the out-of-pocket cost to $0 to $5 for people with commercial insurance, but those programs do not apply to Medicare or Medicaid. If a claim is denied, a headache specialist can often request an appeal or a peer-to-peer review.

Other Peptide Products Are Not CGRP Medications

The word peptide appears on thousands of cosmetic and supplement labels, which creates real confusion. A serum marketed as a peptide for skin, or a tub of collagen peptide supplements, is a cosmetic or food product, not a CGRP drug, and none of them are FDA-approved to prevent or treat migraine.

The same caution applies to peptides with drug-like activity. The pt141 peptide (bremelanotide) is a prescription melanocortin agonist for hypoactive sexual desire disorder, and bpc-157 peptide for inflammation is sold as a research chemical with no approved human use. BPC-157 is not FDA-approved for human use in the United States, and buying it online carries real risk of contamination and dosing errors.

What to Ask Your Doctor

• Does my headache pattern fit migraine or cluster headache?
• Would an antibody or a gepant suit me better, given how often I get attacks?
• Which older preventives have I already tried, and what will my insurer require?
• What should I do if I have side effects or miss a dose?

Bring a headache diary to the visit. Tracking attack frequency, duration, and triggers gives your clinician the data needed to judge whether a CGRP medication is working after two to three months.