An anti-CGRP injection to prevent migraine
Galcanezumab
A monthly self-injection given under the skin to prevent migraine and cluster headache.
What is Galcanezumab?
Galcanezumab (brand name Emgality) is a newer type of medicine, called an anti-CGRP biologic, used to prevent migraine and also cluster headache. It is given as an injection under the skin, usually once a month, and many people learn to inject it themselves at home. It is a preventer, taken regularly to reduce how often attacks happen, so it does not treat a headache that has already started. It works by blocking CGRP, a natural body chemical involved in these headaches. It is generally well tolerated, with reactions where the injection is given being the most common problem. It is usually offered after older preventers have not worked, and it is not recommended in pregnancy without specialist advice.
Education and reference only. This is a plain-language guide to Galcanezumab — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Galcanezumab is a laboratory-made antibody, known as a biologic, that targets a body chemical called CGRP (calcitonin gene-related peptide), which plays a key part in migraine and cluster headache. It is used as a preventer, taken regularly to reduce how often attacks happen rather than to stop one already underway. In the UK it is usually considered for people with frequent or chronic migraine who have tried older preventer medicines without success, and it is also used in cluster headache. It is given as a self-injection under the skin.
How it works
When a migraine or cluster headache develops, levels of CGRP rise and help drive the pain. Galcanezumab attaches to CGRP and stops it working, which over time reduces how often attacks happen and how severe they are. Because it is a preventer, it is given on a regular monthly schedule and its effect builds up gradually rather than relieving pain within minutes. It does not treat an attack that has already begun, so a separate acute treatment is still needed for breakthrough headaches.
Company & origin
Originated / developed by: Eli Lilly.
A newer biologic medicine used in the UK to help prevent migraine, and also cluster headache, in people who have frequent attacks.
What it treats
Conditions Galcanezumab is used for
Practical use
How to take Galcanezumab
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- It is given as an injection under the skin, usually once a month for migraine; the schedule for cluster headache is different and will be explained to you.
- Many people are taught to give the injection themselves at home into the stomach, thigh or upper arm, rotating the site each time.
- Take it regularly to prevent attacks; it will not relieve a headache that has already started, so keep using your usual acute treatment as well.
- Allow a few months to judge whether it is working, as the benefit builds up gradually.
- Tell your specialist if you are pregnant, planning a pregnancy or breastfeeding, as it should only be used on specialist advice.
Weighing it up
Advantages & disadvantages of Galcanezumab
Advantages
- A single monthly self-injection that many people can give themselves at home.
- Generally well tolerated, with fewer body-wide side effects than some older preventer tablets.
- Can be used both for migraine prevention and for cluster headache.
Disadvantages
- It is a preventer only and does not treat an attack that has already begun.
- It is given by injection rather than as a tablet, and commonly causes injection-site reactions.
- It is usually only available after several older preventers have been tried, and its benefit takes some weeks to build.
Practical use
Good to know
It helps to understand the difference between preventers and acute treatments: galcanezumab is a preventer, taken regularly to make attacks less frequent, while you still need a separate medicine to treat a headache when it happens. The anti-CGRP medicines are a newer class developed for people who have not done well with older preventers, so they are usually offered after those have been tried. For migraine it is given as a monthly injection, while the schedule for cluster headache differs and will be explained by your specialist. Benefit is judged over a few months. The most common problem is a reaction at the injection site, such as redness, pain or itching. It should not be used in pregnancy without specialist advice.
Who should not take it / use with caution
- It should not be used in pregnancy unless a specialist advises, and is best discussed before planning a pregnancy or while breastfeeding.
- People who have had a serious allergic reaction to galcanezumab or its ingredients should not use it.
- It is used with care in people with certain heart or blood-vessel conditions, who should discuss this with their specialist.
Monitoring
- Reviewing after a few months whether the number and severity of attacks has reduced enough to continue.
- Checking for injection-site reactions and any signs of an allergic reaction.
- Discussing pregnancy plans, breastfeeding and overall headache control at review.
Side effects
- Reactions where the injection is given, such as redness, pain or itching, are the most common and are usually mild.
- Some people get constipation, dizziness or itching.
- Rarely, a more serious allergic reaction can occur, which needs urgent medical attention.
Key interactions
- It has few known interactions with other medicines, as it works on CGRP rather than being processed like ordinary tablets.
- It can be used alongside acute treatments for attacks, but tell your team about everything you take.
- Always tell your specialist about other preventer medicines so your overall plan can be reviewed.
Available as: A pre-filled pen or syringe for injection under the skin.
Answers
Galcanezumab: frequently asked questions
Will galcanezumab treat a migraine I already have?
No. It is a preventer taken regularly to make attacks less frequent, so you still need a separate acute treatment for a headache that has already started.
Can I inject it myself?
Yes, many people are taught to give the monthly injection themselves at home into the stomach, thigh or upper arm.
Is it used for cluster headache too?
Yes, galcanezumab is used both to prevent migraine and to treat cluster headache, though the schedule for cluster headache is different.
How long before I know if it helps?
Its benefit builds up gradually, so it is usually judged over a few months before deciding whether to continue.
Can I use it in pregnancy?
It should not be used in pregnancy without specialist advice, so discuss it if you are pregnant, planning a pregnancy or breastfeeding.
The wider class
About Anti-CGRP biologic (migraine prevention)
Galcanezumab belongs to the anti-cgrp biologic (migraine prevention) class. For how the class as a whole works, its shared safety principles and monitoring, see the full guide.
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Authoritative sources
- BNF
- NICE CKS
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