CGRP Inhibitors for Preventing Migraines

Aimovig, Ajovy, and Emgality

Calcitonin gene-related peptide (CGRP) inhibitors are a relatively new type of medication for preventing chronic and episodic migraine headaches (with or without aura). They also can reduce the number of days per month a migraine sufferer has headaches. Currently, three CGRP inhibitors have been approved by the U.S. Food and Drug Administration (FDA): Aimovig (erenumab-aooe), Ajovy (fremanezumab-vfrm), and Emgality (galcanezumab-gnlm).

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They're proving to have distinct advantages over more classic prophylactic migraine drugs—the so-called oral migraine preventive medications (OMPMs), such as beta blockers, anti-seizure medications, and antidepressants.

Notably, CGRP inhibitors don't cause the same types of unpleasant side effects that often make OMPMs difficult or even impossible for some people to take. In fact, in clinical trials, CGRP inhibitors have been found to be remarkably free of major side effects altogether.

If you have chronic or episodic migraines and have found that OMPMs don't work well for you or cause side effects that you can't tolerate, you may want to consider trying a CGRP inhibitor.

CGRP and Migraine Symptoms

CGRP is a protein present in the trigeminal ganglia nerve, a cranial nerve that is responsible for facial sensation that recently has been found to play a role in migraines by causing dilatation of cranial blood vessels. CGRP may also mediate the transmission of pain from the dilated vessels to the brain and promote neurogenic inflammation.

As a migraine attack progresses, the brainstem becomes sensitized, leading to a vicious cycle of head pain and an increased sensitivity to the environment. This is why people often find light, noise, or odors to be unbearable during a migraine attack.

Preventive migraine medications that target this protein work by blocking the docking site of the CGRP receptor (Aimovig) or the CGRP protein itself (Ajovy and Emgality). They are in a class of biologic drugs called monoclonal antibodies.

Aimovig, Ajovy, and Emgality

The three CGRP inhibitors that have been approved by the FDA for preventing migraine headaches—Aimovig, Ajovy, and Emgality—share several similar advantages:

Administered by Subcutaneous Injection

This means they're "taken" via a shot with a thin needle into fatty tissue (rather than deep into muscle). Most people give themselves these injections into the thigh or belly after being taught how by a medical practitioner. CGRP inhibitors also can be injected into the upper arm by someone else.


None of the CGRP inhibitors are taken every day. Aimovig and Emgality are taken once a month as one or two successive shots, depending on the dose. Ajovy is taken once a month (one injection) or once every three months (three injections, one after the other).

Mild Side Effects

The main ones are redness, pain, or swelling at the injection site—all common and temporary occurrences after an injection of any type. Aimovig also has been associated with constipation.

Less often, someone may experience an allergic reaction after a CGRP inhibitor shot. Symptoms can include rash, hives, itching, difficulty breathing, and swelling of the face, tongue, or throat.

If you take an CGRP inhibitor and experience any symptoms of a reaction, you should get immediate medical attention. Note that these more serious side effects can occur days or even up to a month after taking the medication.


For a report published in July 2018, the Institute for Clinical and Economic Review (ICER) reviewed 11 clinical trials of CGRP inhibitors for preventing chronic migraine and eight trials of CGRP inhibitors for preventing episodic migraines.

The ICER found that, overall, migraine patients who took CGRP inhibitors had greater reductions in headache days per month versus taking other preventive medications. What's more, there were "higher odds of 50 percent response, and greater reductions in days using acute medication per month for all of the interventions versus placebo."

In short, all three FDA-approved CGRP inhibitors, as well as eptinezumab (which is still being studied), have earned an important spot in the arsenal of medications that prevent migraines.

A Word From Verywell

There's no question managing migraine headaches can be tricky. How people experience them and the way they respond to treatments can vary widely. But given that at least in the case of preventive medications there is a tendency for patients to be unable to tolerate classic OMPMs, the development of drugs with fewer side effects is welcome. If you've been unable to find a medication that keeps your headaches from occurring, it may make sense to talk to your doctor about trying a CGRP.

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  2. Chiu IM, Von hehn CA, Woolf CJ. Neurogenic inflammation and the peripheral nervous system in host defense and immunopathology. Nat Neurosci. 2012;15(8):1063-7. doi:10.1038/nn.3144

  3. American Migraine Foundation. Migraine with brainstem aura (basilar type migraine). Updated October 8, 2016.

  4. Castle D, Robertson NP. Monoclonal antibodies for migraine: an update. J Neurol. 2018;265(6):1491-1492. doi:10.1007/s00415-018-8886-8

  5. U.S. Food and Drug Administration. New drug class employs novel mechanism for migraine treatment and administration. Updated January 29, 2019.

  6. Amgen, Inc. Patient information AIMOVIG® (AIM-oh-vig) (erenumab-aooe) injection, for subcutaneous use. Updated October 2019.

  7. American Journal of Managed Care. ICER releases final evidence report on efficacy, cost effectiveness of CGRP inhibitors for migraine. Updated July 14, 2018.

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