Fremanezumab (Ajovy) is a drug you inject to prevent migraines in adults. Like most drugs, it can come with side effects.
Most of the time, these effects are mild and you can manage them at home. Serious side effects are much less common but can happen. Here’s what to look for so you’ll know what to do on your own and when to call your doctor.
How to Manage the Most Common Side Effects of Fremanezumab (Ajovy)
Injection-site reactions are the most common side effects of this drug. They can cause pain, swelling, or redness in the body part where you injected the drug. These effects are rarely serious and often go away on their own.
Injection-site reactions can happen if your body reacts to the needle or to the medication. You may feel or see these effects right after the shot or hours later. To ease symptoms, you can:
- Apply a cold pack to the injection site to help tamp down pain, itching, or swelling.
- Use an over-the-counter (OTC) pain reliever, which may ease your discomfort and lower inflammation. These drugs include acetaminophen and ibuprofen.
If you use an OTC pain reliever, be careful not to take it too often. If you use them most days of the week or more, you can get what’s called a “medication overuse headache” or “rebound headache.” That’s why you shouldn’t use these meds for more than 2 or 3 days a week or 15 days a month.
Call your doctor if you have a fever of 100.4 degrees or higher, or if an injection-site reaction gets worse instead of better.
How to Manage Less Common Side Effects of Fremanezumab (Ajovy)
Upset stomach or nausea. In studies of fremanezumab, a small share of people said it upset their stomach. To calm an upset stomach at home:
- Drink very cold clear fluids.
- Eat bland foods such as plain crackers.
- Skip fried foods and sweets until you feel better.
- Rest after eating.
- Sip fluids slowly.
Talk to your doctor if your nausea lasts more than a week.
Constipation. A tiny number of people in the studies got constipated while taking fremanezumab. To ease constipation:
- Slowly increase fiber in your diet by eating more fresh fruits, vegetables, and whole-grain breads and cereals.
- Get more exercise.
- Don’t ignore the urge to use the bathroom. Don’t rush your bowel movements. Take your time.
- Take an OTC fiber supplement, stool softener, or other laxative.
If these things don’t help and your constipation won’t go away, talk to your doctor.
High blood pressure. Doctors are still learning how much fremanezumab affects blood pressure (BP), or hypertension. In early short studies of the drug, a few people had high BP. But in a study of the drug that lasted longer, people’s BP stayed the same or got lower.
Researchers are watching carefully for any BP side effects with fremanezumab. That’s because the drug works on a molecule in your body called calcitonin-gene related peptide (CGRP). It can affect your cardiovascular system, so problems may be possible.
Another type of drug that targets CGRP, erenumab (Aimovig), now has a warning that the drug can cause high BP.
High BP usually has no symptoms, so you should measure it regularly. Staff at your doctor’s office can measure it for you during a visit, or you can measure it yourself at a pharmacy or with a home monitor.
When high BP does cause symptoms, they can include:
- Chest pain
- Irregular (too fast or too slow) heartbeat
- Nosebleeds
- Vision changes
- Fatigue
- Upset stomach
- Vomiting
- Confusion
To lower your risk of high BP:
- Exercise.
- Watch your weight.
- Eat a healthy diet.
- Drink less alcohol.
- Don’t smoke.
- Use less salt in your diet.
Researchers are doing more study on fremanezumab to make sure it’s safe for people who are at risk for high BP and other cardiovascular problems.
How to Manage Serious Side Effects of Fremanezumab (Ajovy)
This medication can cause allergic reactions. They usually happen within minutes to a few hours after you inject the drug, and sometimes up to a month later.
Most allergic reactions aren’t serious. They can cause:
- Itching
- Rashes
- Hives
If you have one of these reactions, talk to your doctor about stopping fremanezumab injections. Treatment for this type of reaction can include:
- OTC antihistamines, drugs used to treat allergies
- Prescription drugs that lower inflammation, such as steroids
Fremanezumab can also cause a severe allergic reaction, called anaphylaxis, that can kill you. Signs of anaphylaxis include:
- Swelling of your tongue or throat
- Trouble breathing
- Low blood pressure
- Dizziness or fainting
- A weak or rapid pulse
- Vomiting or diarrhea
This type of reaction is a medical emergency, and you should call 911.
Antibodies Against Fremanezumab (Ajovy)
Fremanezumab is a monoclonal antibody. When you take it, your body may develop antibodies that block its action. This can stop the drug from working as well as it did.
This doesn’t happen often with fremanezumab. In studies, less than 2% of people taking the drug developed antibodies to it. An early signal that you’ve developed antibodies might be that the drug doesn’t work as well for you anymore. If this happens, talk to your doctor.
