Zynlonta (loncastuximab tesirine-lpyl) is a brand-name drug that’s prescribed for certain types of large B-cell lymphoma in adults. As with other drugs, Zynlonta can cause side effects, such as nausea, fatigue, and skin rash.

Zynlonta 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 treatment with Zynlonta in clinical trials:

* For more information about this side effect, see “Side effect specifics” below.

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

Mild side effects that have been reported with Zynlonta 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 and reviews side effects of the medication. If you develop a side effect while using Zynlonta and want to tell the FDA about it, visit MedWatch.

* An allergic reaction is possible after using Zynlonta. However, this side effect wasn’t reported in clinical trials. To learn more, see the “Side effect specifics” section below.

Zynlonta may cause serious side effects. The list below may not include all possible serious side effects of the drug. For more information, you can refer to Zynlonta’s prescribing information.

If you develop serious side effects while using Zynlonta, 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:

* For more information about this side effect, see “Side effect specifics” below.
† An allergic reaction is possible after using Zynlonta. However, this side effect wasn’t reported in clinical trials. To learn more, see the “Side effect specifics” section below.

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

Fluid retention

Fluid retention was a common side effect reported in clinical studies of Zynlonta. Fluid retention is also known as edema. Most of the time, this side effect is mild. But sometimes, a more serious type of edema, called effusion, can occur. Effusion is when there’s an irregular collection of fluid in between tissues in the body. This can cause organs in the body to not work as usual. In studies of Zynlonta, pleural effusion (fluid buildup around the lungs) and pericardial effusion (fluid buildup around the heart) occurred but were rare.

The most common symptom of edema is swelling. This can occur anywhere in the body but most often is seen in the abdomen, hands, and legs. Other symptoms of edema or effusion may include:

  • bloating
  • weight gain that happens quickly
  • chest pain
  • trouble breathing

What you can do

If you have chest pain or trouble breathing, talk with your doctor right away. This could be a more serious condition, such as pleural effusion or pericardial effusion. The treatment your doctor recommends will depend on your condition. Your doctor will likely have you temporarily or permanently stop using the medication.

Low levels of blood cells

Zynlonta can decrease the levels of red blood cells, white blood cells, and platelets. This was a common side effect in clinical studies of the drug. Depending on which blood cells are low, you may have different symptoms.

If your red blood cells are low, this results in anemia. Your red blood cells carry oxygen from your lungs to the rest of your body. Mild anemia doesn’t usually cause symptoms. But if anemia becomes more severe, you may see symptoms such as:

  • fatigue
  • shortness of breath
  • pale skin
  • fast heartbeat

When white blood cells are low, this results in neutropenia. Your white blood cells help fight off infections. You may be at increased risk of infections if your white blood cells are too low. It’s important to tell your doctor right away if you have symptoms of an infection that may include:

  • fever
  • chills
  • weakness
  • difficulty breathing

If you have low platelets, this results in thrombocytopenia. Your platelets form clots that help you stop bleeding. A mild decrease in platelets usually doesn’t cause a problem. When platelet levels are severely low, you may see symptoms that include:

What you can do

During your treatment with Zynlonta, your doctor will regularly order a blood test known as a complete blood count (CBC). This test measures the levels of different blood cell types. It’s important to have all the blood tests that your doctor orders.

If your doctor finds you have low blood cell counts, they’ll recommend a treatment based on which blood cells are low and how low your levels are. This may include antibiotics, blood cell transfusions, or other medications. Also, be sure to tell your doctor if you have any symptoms of anemia, neutropenia, or thrombocytopenia. In some cases, they may have you temporarily stop treatment with Zynlonta.

Allergic reaction

As with most drugs, Zynlonta can cause an allergic reaction in some people. However, this side effect wasn’t reported 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 using Zynlonta. 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 receive Zynlonta. 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:

Diabetes: Zynlonta can cause an increase in blood sugar. If you have diabetes, treatment with Zynlonta can worsen your condition. It also can make your diabetes harder to manage. Talk with your doctor about how to best manage your diabetes while receiving Zynlonta.

Liver problems: If you have liver problems or have had liver problems in the past, your body may not break down Zynlonta as it should. This can raise your risk of side effects. Talk with your doctor about whether you can receive Zynlonta before starting treatment. If you have mild liver problems, such as steatotic liver disease (previously called fatty liver disease), your doctor may want to monitor your liver more closely while you’re receiving treatment. It’s not known whether Zynlonta is safe for you to receive if you have moderate or severe liver disease, such as liver failure.

Infection: If you have an infection or recently had one, tell your doctor before receiving treatment. Zynlonta can decrease certain blood cell levels, including a type of white blood cells called neutrophils. This can lower your body’s ability to fight off an infection. Your doctor will likely want to wait until your infection is gone before starting Zynlonta treatment.

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

Pregnancy or breastfeeding: If you’re pregnant or breastfeeding your child, Zynlonta may not be safe for you to use. Talk with your doctor before receiving Zynlonta if you’re pregnant, planning to become pregnant, or breastfeeding.

Alcohol consumption: If you drink alcohol, talk with your doctor about whether Zynlonta is safe for you to drink.

Like most medications, Zynlonta can cause side effects. Some side effects may be severe and require treatment. Talk with your doctor if you develop side effects that are bothersome or serious.

If you’d like to learn more about Zynlonta, talk with your doctor or pharmacist. They can help answer any questions you have about side effects from using the drug.

Besides talking with your doctor, you can do some research on your own. These articles might help:

  • More information about Zynlonta: For details about other aspects of Zynlonta, refer to this article.
  • Dosage: For information about the dosage of Zynlonta, view this article.

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.