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Medically Approved

What is a migraine shot?

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How does it work?TypesDurationSide effectsSummary
A migraine shot is a liquid injection that treats migraine. Several types of injections prevent and treat migraine, with the effects lasting up to 1 month.
Medically reviewed by Alexandra Perez, PharmD, MBA, BCGP
Written by Hayley Osborne
Updated on

Migraine is an episodic headache associated with certain features, such as sensitivity to light, sound, or movement. The condition can fall under two categories: resistant migraine and refractory migraine.

The American Migraine Foundation estimates around 39 million people in America live with migraine. Still, the number could be higher as some people may not seek treatment or a diagnosis.

How does a migraine shot work?

An image of someone holding an injection.
yacobchuk/Getty Images

A doctor may prescribe migraine shots to people with resistant or refractory migraine when other treatment methods have not worked.

Resistant migraine refers to episodes that:

  • fail to improve after using three different preventives
  • are frequent for 8 debilitating days a month
  • last for 3 months or more

Refractory migraine tends to be unresponsive to any preventive medications and can last for around 8 debilitating days a month for 6 months or more.

Migraine can occur when a molecule called calcitonin gene-related peptide (CGRP) found in our nervous system is released. CGRP widens the body’s blood vessels, which worsens inflammation and pain.

Preventive migraine injections block CGRP and their receptors using monoclonal antibodies (laboratory-produced immune system proteins that bind to a specific target). These help narrow the blood vessels and stop pain signals from being sent from the brain, reversing the symptoms of CGRP release.

A 2021 review notes that the release of CGRP is sufficient to induce migraine and that drugs targeting CGRP or its receptor are effective in migraine treatment.

Types of migraine shots


Fremanezumab (Ajovy) is an injection that stops the release of CGRP and prevents migraine episodes from occurring. You can take it once a month or every 3 months, and you inject it into fatty tissue, usually in the thigh or stomach area.

Trials have shown it reduced the number of headache days for people with episodic and chronic migraine.

Side effects can include hypersensitivity reactions such as rashes and hives.

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Sumatriptan (Imitrex) is a migraine medication that prevents the release of CGRP by binding to serotonin receptors in the brain and causing its blood vessels to narrow. It’s usually taken once a migraine has begun and is available in the following forms:

  • injection, typically given in the outer thigh
  • tablets
  • nasal spray

While sumatriptan doesn’t prevent migraine or the frequency in which it appears, it can help with the pain when it occurs. It can take 30 to 60 minutes to work and is the fastest-acting migraine injection.

Side effects can include:

  • feeling or being sick
  • dizziness
  • lethargy

You should not take sumatriptan with other migraine preventive medications such as ergotamine or other triptans.


Galcanezumab (Emgality) is a prescription treatment that attaches itself to and blocks CGRP. You use it once a month to prevent migraine and is most suitable for those who experience migraine episodes at least four times a month.

A 2020 trial into the effectiveness of galcanezumab notes that those who took the drug rather than a placebo reported 4.1 fewer migraine days a month. It also worked well for people who had not previously benefited from other preventive migraine methods.

Side effects can include:

  • itching
  • hives
  • swelling of the face and tongue
  • difficulty breathing

Emgality can be a good option if you cannot take other preventive medications due to drug interactions.

Valproic acid

Valproic acid (Depakene) is primarily used to treat bipolar disorder and seizures but can also effectively prevent migraine. A healthcare professional will inject the medication into a vein.

It increases gamma-aminobutyric acid (GAMA) levels in your brain, suppressing inflammation and migraine-related events in your cortex. It also helps promote feelings of calm. It can be a suitable alternative for people who don’t respond well to other therapies.

You should always speak with a healthcare professional before starting or stopping treatment, especially if you’re pregnant.


Dihydroergotamine (DHE) is a migraine injection targeted purely at relieving the pain of migraine. It belongs to a class of drugs called ergot alkaloids and works by tightening blood vessels and stopping the release of chemicals that cause the brain to swell.

You or your healthcare professional will inject DHE into fatty layers, muscles, or a vein. You should take it at the first sign of a migraine. You can take additional doses the hour after the first injection, but no more than 3 within 24 hours.

Side effects can include:

  • tingling in the throat or nose
  • lethargy
  • change in taste
  • vomiting
  • dizziness

DHE can damage the heart and organs if taken too often. You should only use it to treat a migraine while it’s happening — it can’t be used to prevent one.

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The Food and Drug Administration (FDA) approved Aimovig in 2018 as a preventive treatment for migraine. You inject it into fatty layers, such as the stomach area or thighs, and it blocks CGRP receptors.

A 2019 review notes that after starting treatment with Aimovig, around one-third of participants had their migraine days decreased by half every month. Around half of the participants found that taking Aimovig lifted their previous day-to-day limitations from migraine.

Common side effects include:

  • redness and swelling at the injection site
  • constipation
  • muscle cramps or spasms

If symptoms haven’t improved after 3 months of taking Aimovig, you should speak with a medical professional.


Eptinezumab (Vyepti) is a monoclonal antibody (a protein that can bind to target areas within the body) that prevents the release of CGRP to prevent migraine. A healthcare professional will deliver the medication via IV every month, taking around 30 minutes when administered.

A 2020 study notes that eptinezumab can significantly reduce migraine frequency. Some side effects include hypersensitive reactions, such as itching and a stuffy nose.

How long does a migraine shot last?

The duration of effective migraine treatment can depend on the migraine shot, with some able to provide relief for around 1 month, while others can last for about 3 months. Instead of preventing migraine, other migraine injections administered solely for pain symptoms, can last about 24 hours.

Side effects of migraine shots

Although side effects can vary between the different medications, they can generally include:

More serious, allergic side effects can include difficulty breathing and throat, tongue, and face swelling. In this case, you should seek urgent medical help.


Migraine can be debilitating due to the frequency and consistency of pain. The use of migraine injections can help prevent migraine episodes and ease the pain associated with them.

Migraine injections can deliver positive effects by decreasing the number of days migraine can affect you monthly and help elevate your quality of life.

It is vital that you speak with your healthcare professional before using any migraine injections, as they can’t always be taken alongside other medications and can also be harmful if you’re pregnant.

If you need help covering the cost of medications, Optum Perks’ free Discount Card could help you get up to 80% off prescription medication. See how much you can save on your medication here.

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