Leqembi (lecanemab-irmb) is a brand-name infusion that’s prescribed for certain adults with Alzheimer’s disease. As with other drugs, Leqembi can cause side effects. These include infusion-related reactions and headache.
Leqembi is a biologic and belongs to a drug class called amyloid beta-directed antibodies. The drug is not available in a biosimilar version.
Read on to learn about potential common, mild, and serious side effects of Leqembi. For a general overview of the drug, including details about its uses, see this article.
Leqembi can cause certain side effects, some of which are more common than others. These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.
These are just a few of the more common side effects reported by people who took Leqembi in clinical trials:
* Leqembi has a
† For more information about this side effect, see “Side effect specifics” below.
Mild side effects can occur with Leqembi use. This list doesn’t include all possible mild side effects of the drug. For more information, you can refer to Leqembi’s prescribing information.
Mild side effects that have been reported with Leqembi include:
- cough
- diarrhea
- nausea or vomiting
- skin rash
- headache*
- mild infusion-related reaction*
- mild allergic reaction†
These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.
Note: After the Food and Drug Administration (FDA) approves a drug, it tracks side effects of the medication. If you develop a side effect while receiving Leqembi and want to tell the FDA about it, visit MedWatch.
* For more information about this side effect, see “Side effect specifics” below.
† An allergic reaction is possible after injecting Leqembi. However, it’s not clear whether this side effect occurred in clinical trials. To learn more, see the “Side effect specifics” section below.
Leqembi may cause serious side effects. However, most serious side effects weren’t common in clinical trials. The list below may not include all possible serious side effects of the drug. For more information, you can refer to Leqembi’s prescribing information.
If you develop serious side effects while receiving Leqembi, call your doctor right away. If the side effects seem life threatening or you think you’re having a medical emergency, immediately call 911 or your local emergency number.
Serious side effects that have been reported and their symptoms include:
- Low white blood cell levels. Symptoms can include:
- frequent infection
- fever
- Atrial fibrillation. Symptoms can include:
- chest pain
- dizziness
- Amyloid-related imaging abnormalities.*
- Serious infusion-related reaction.†
- Severe allergic reaction.‡
* Leqembi has a
† For more information about this side effect, see “Side effect specifics” below.
‡ An allergic reaction is possible after injecting Leqembi. However, it’s not clear whether this side effect occurred in clinical trials. To learn more, see the “Side effect specifics” section below.
Learn more about some of the side effects that Leqembi may cause. To find out how often side effects occurred in clinical trials, see the prescribing information for Leqembi.
Risk of amyloid-related imaging abnormalities
Leqembi has a
ARIA are changes in your brain that can be detected by an MRI scan. They can include swelling or bleeding in your brain. In most cases, the swelling is temporary and will improve over time. Bleeding typically occurs in small spots on the brain. However, it’s also possible for bleeding to occur in larger areas of the brain.
Symptoms of ARIA are possible but not common. When they do occur, symptoms typically improve over time. These symptoms may include:
- confusion
- headache
- dizziness
- difficulty walking
- changes in vision
- seizure
What you can do
Before and during your Leqembi treatment, your doctor will take MRI scans of your brain. This allows them to monitor your brain for any changes that may occur.
If you develop any symptoms of ARIA during treatment, contact your doctor right away. However, if you think you’re having a medical emergency, immediately call 911 or go to the hospital. They can do a scan of your brain to see if you’re experiencing ARIA.
In addition, it’s important to tell your doctor about any conditions you have or medications you take before starting treatment. You may have a higher risk of ARIA if you’ve previously had a stroke or another condition affecting your brain. Certain medications or genetic factors may also increase your risk. Your doctor will decide whether Leqembi is safe for you to take.
Headache
It’s possible to experience a headache during your treatment with Leqembi. In clinical trials, headache was one of the most commonly reported side effects.
What you can do
If you experience a persistent or bothersome headache during treatment with Leqembi, talk with your doctor. They can recommend ways to manage this side effect, such as taking an over-the-counter medication. Examples of headache medications include Tylenol (acetaminophen) and Advil (ibuprofen). For more information about headache medications, see this article.
Infusion-related reactions
Leqembi may cause an infusion-related reaction. Infusion-related reactions may occur during or after you receive your dose of Leqembi.
In the drug’s clinical trials, infusion-related reactions were common. This type of reaction can be mild or serious and can include:
- fever
- nausea or vomiting
- dizziness
- changes in your heart rate
- difficulty breathing
- flu-like symptoms, such as body aches or joint pain
What you can do
If you notice an infusion-related reaction during or after your dose of Leqembi, tell your doctor. In some cases, they may suggest taking another medication before your dose of Leqembi. For example, they may recommend Benadryl (diphenhydramine) or Tylenol (acetaminophen). These medications can help manage certain infusion-related reactions that you may experience.
Allergic reaction
As with most drugs, Leqembi can cause an allergic reaction in some people. However, it’s not clear whether this side effect occurred in clinical trials.
Symptoms can be mild or serious and can include:
- skin rash
- itching
- flushing
- swelling under your skin, typically in your eyelids, lips, hands, or feet
- swelling of your mouth, tongue, or throat, which can make it hard to breathe
What you can do
For mild symptoms of an allergic reaction, call your doctor right away. They may recommend ways to ease your symptoms and determine whether you should keep receiving Leqembi. However, if your symptoms are serious and you think you’re having a medical emergency, immediately call 911 or your local emergency number.
Before you start Leqembi treatment, be sure to tell your doctor about any other medications you take or medical conditions you may have. Your doctor can help decide whether Leqembi is a safe treatment option for you.
Boxed warning: Risk of amyloid-related imaging abnormalities
This drug has a
Other precautions
Be sure to talk with your doctor about your health history before you take Leqembi. This drug may not be the right treatment for you if you have certain medical conditions or other factors that affect your health. These are considered drug-condition or drug-factor interactions. The conditions and factors to consider include:
Allergic reaction. If you’ve had an allergic reaction to Leqembi or any of its ingredients, your doctor will likely not prescribe Leqembi. Ask your doctor what other medications may be better options for you.
Alcohol with Leqembi
There are no known interactions between Leqembi and alcohol.
However, alcohol and Leqembi may share certain side effects. These include nausea, vomiting, and headache. For this reason, drinking alcohol during your treatment may increase your risk of these side effects.
In addition, drinking alcohol may worsen symptoms of Alzheimer’s disease, which Leqembi is prescribed to treat. This is because both Alzheimer’s disease and alcohol consumption can cause confusion or memory problems. So, drinking alcohol may make symptoms of your condition worse.
If you have questions about drinking alcohol during Leqembi treatment, talk with your doctor or pharmacist. To learn more about alcohol and Alzheimer’s disease, see this article.
Pregnancy and breastfeeding while receiving Leqembi
It’s not known whether Leqembi is safe to receive during pregnancy or while breastfeeding.
At this time, there haven’t been any clinical trials to determine whether the drug is safe to receive during pregnancy. It’s also unclear what effects it may have on a developing fetus.
In addition, there haven’t been any clinical trials to know whether Leqembi passes into breast milk. For this reason, it’s unknown how the drug may affect a child who’s breastfed.
If you’re pregnant, breastfeeding, or planning for either, talk with your doctor before starting treatment with Leqembi.
In most cases, side effects of Leqembi are mild. However, serious side effects are also possible from receiving this medication. If you’d like to learn more about Leqembi, talk with your doctor or pharmacist. They can help answer any questions you have about side effects of the drug.
Besides talking with your doctor, you can do some research on your own. These articles might help:
- More information about Leqembi. For details about other aspects of Leqembi, refer to this article.
- A look at your condition. For details about Alzheimer’s disease, see our dementia hub.
Disclaimer: Medical News Today has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.