Monjuvi (tafasitamab-cxix) is a brand-name intravenous (IV) infusion that’s prescribed to help treat diffuse large B-cell lymphoma. As with other drugs, Monjuvi can cause side effects. These include fatigue, diarrhea, and low blood cell count.

Monjuvi 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 received Monjuvi in clinical trials:

For more information about some of these side effects, see the “Side effect specifics” section.

Mild side effects can occur with Monjuvi use. This list doesn’t include all possible mild side effects of the drug. For more information, you can refer to Monjuvi’s prescribing information.

Mild side effects that have been reported with Monjuvi include:

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 Monjuvi and want to tell the FDA about it, visit MedWatch.

For more information about some of these side effects, see the “Side effect specifics” section.

Monjuvi may cause serious side effects. Although serious side effects aren’t common, they can occur. The list below may not include all possible serious side effects of the drug. For more information, you can refer to Monjuvi’s prescribing information.

If you develop serious side effects while receiving Monjuvi, 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:

Monjuvi may cause several side effects. Here are some frequently asked questions about the drug’s side effects and their answers.

Are side effects of Monjuvi similar to side effects seen with Ozempic or Wegovy?

Monjuvi belongs to a separate drug class and is prescribed for different conditions than Ozempic (semaglutide) and Wegovy (semaglutide).

Monjuvi belongs to a class of drugs called CD19-directed cytolytic antibodies. It’s prescribed to treat a type of cancer called diffuse large B-cell lymphoma.

In contrast, Ozempic and Wegovy belong to a group of drugs called glucagon-like peptide-1 (GLP-1) agonists. Ozempic is prescribed for certain conditions in adults with type 2 diabetes. Wegovy is prescribed for certain uses in adults with obesity or overweight.

To learn about how the side effects of these drugs compare, talk with your doctor or pharmacist. You can also read these articles about Ozempic side effects and Wegovy side effects.

Note: It’s possible that Monjuvi may be confused with Mounjaro (tirzepatide), which is another GLP-1 agonist that may be prescribed in adults with type 2 diabetes. See this article to learn about Mounjaro’s side effects. You can also talk with your doctor or pharmacist to learn more.

How long do side effects of Monjuvi typically last?

It depends on the specific side effect. For example, an infusion-related reaction may occur during or directly after your infusion. Then it may go away until you receive your next infusion. (To learn more about this side effect, see the “Side effects specifics” section.)

However, other side effects, such as fatigue or appetite loss, may last throughout your treatment with Monjuvi.

If you have questions about specific side effects, talk with your doctor. They can help determine how long certain side effects may last, as well as how to manage them.

Learn more about some of the side effects that Monjuvi may cause. To find out how often side effects occurred in clinical trials, see the prescribing information for Monjuvi.

Diarrhea

It’s possible for Monjuvi to cause diarrhea. In fact, diarrhea was one of the most commonly reported side effects in Monjuvi’s clinical trials.

Symptoms of diarrhea may include abdominal pain, cramps, or bloating. If you experience diarrhea, you may also have more frequent bowel movements.

What you can do

If you experience severe or bothersome diarrhea during your treatment with Monjuvi, talk with your doctor. In some cases, diarrhea may lead to dehydration.

Your doctor or pharmacist can suggest ways to manage this symptom. For example, they may recommend taking an over-the-counter medication, such as Imodium (loperamide), to treat your diarrhea.

Infusion-related reaction

It’s possible to experience an infusion-related reaction from Monjuvi. These are side effects that may occur while you receive your dose of Monjuvi. In clinical trials, infusion-related reactions were common.

Examples of infusion-related reactions include:

What you can do

If you experience an infusion-related reaction during Monjuvi treatment, tell your doctor. Depending on your symptoms, they may be able to recommend ways to reduce this side effect. For example, taking Tylenol (acetaminophen) or Benadryl (diphenhydramine) before your infusion may help prevent certain infusion-related reactions.

In some cases, your doctor may recommend pausing your infusion until your symptoms improve. If you have a severe infusion-related reaction, your doctor may recommend stopping treatment with Monjuvi. In this case, they can recommend a different treatment option for you.

Allergic reaction

As with most drugs, Monjuvi can cause an allergic reaction in some people. However, it’s not clear whether this side effect occurred in clinical trials.

In general, symptoms of allergic reaction can be mild or serious.

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 Monjuvi. However, if your symptoms are serious and you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Be sure to talk with your doctor about your health history before you take Monjuvi. 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:

Infection: Before starting Monjuvi treatment, tell your doctor if you have an infection. This medication can weaken your immune system. In turn, this can make it more difficult for your body to respond to an infection. If you have an infection, your doctor will likely want to treat it before you start receiving Monjuvi infusions.

Allergic reaction: If you’ve had an allergic reaction to Monjuvi or any of its ingredients, your doctor will likely not prescribe Monjuvi. Ask your doctor what other medications may be better options for you.

Pregnancy or breastfeeding: If you’re pregnant or breastfeeding, Monjuvi is not considered safe for you to take. Monjuvi may cause problems with fetal development if given during pregnancy. Monjuvi is also given in combination with the drug Revlimid (lenalidomide). Revlimid is not safe to take during pregnancy and can cause harm to a developing fetus. Due to this risk, your doctor will likely recommend using birth control during treatment with Monjuvi and for at least 3 months after your last dose.

Also, your doctor will likely recommend that you do not breastfeed during Monjuvi treatment or for at least 3 months after your last dose. It’s not known if Monjuvi can affect a child who is breastfed. But due to the possibility of side effects, your doctor won’t likely recommend breastfeeding during Monjuvi treatment.

If you’re pregnant, breastfeeding, or planning for either, tell your doctor before starting Monjuvi. They can recommend other treatment options for your condition.

Alcohol consumption: There aren’t any known interactions between Monjuvi and alcohol. If you have questions about drinking alcohol during treatment, talk with your doctor or pharmacist. Your doctor may recommend you avoid alcohol during your cancer treatment.

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.