Epkinly (epcoritamab-bysp) is a prescription drug used to treat certain forms of B-cell lymphoma. Epkinly can cause side effects ranging from mild to serious. Examples include injection site reactions and cytokine release syndrome.

Epkinly is used to treat diffuse large B-cell lymphoma in adults in certain situations. The drug comes as a liquid solution that’s given as an injection under your skin by a healthcare professional.

Epkinly contains the active ingredient epcoritamab-bysp.* (An active ingredient is what makes a drug work.)

Keep reading to learn about common, mild, and serious side effects Epkinly can cause. For a general overview of the drug, including details about its uses, see this article.

* The reason “-bysp” appears at the end of the drug’s name is to show that it’s distinct from similar medications that may be created in the future.

Some people may experience mild to serious side effects during Epkinly treatment. Examples of the drug’s commonly reported side effects include:

* To learn more about this side effect, see the “Side effects explained” section below.

Mild side effects have been reported with Epkinly. These include:

In most cases, these side effects should be temporary. And some may be easily managed. But if you have symptoms that are ongoing or bothersome, talk with your doctor or pharmacist. And do not stop Epkinly treatment unless your doctor recommends it.

Epkinly may cause mild side effects other than those listed above. See the drug’s prescribing information for details.

* To learn more about this side effect, see the “Side effects explained” section below.
† An allergic reaction is possible after receiving Epkinly, but this side effect wasn’t reported in studies.

Serious side effects have been reported with Epkinly. These include:

  • low white blood cell count, which can increase the risk of infection
  • low red blood cell count, which can cause tiredness and shortness of breath
  • low platelet count, which can cause bruising or bleeding problems
  • serious infections that can be life threatening or even lead to death
  • boxed warning: risk of CRS and immune effector cell-associated neurotoxicity syndrome (ICANS)*
  • severe allergic reaction*†

If you develop serious side effects during Epkinly treatment, 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.

* To learn more about this side effect, see the “Side effects explained” section below.
† An allergic reaction is possible after receiving Epkinly, but this side effect wasn’t reported in studies.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews side effects of the medication. If you’d like to notify the FDA about a side effect you’ve had with Epkinly, visit MedWatch.

Get answers to some frequently asked questions about Epkinly’s side effects.

How do side effects of Epkinly compare with those of Rituxan?

Epkinly and Rituxan (rituximab) are both used to treat certain types of B-cell lymphoma, but they work in different ways. Epkinly is a form of immunotherapy, which is a treatment that helps your immune system attack the cancer cells. Rituxan is a targeted therapy that directly attacks the cancer cells.

These drugs can cause some similar side effects. For example, both can increase your risk of serious infections.

But they can also cause some different side effects. For instance, Epkinly can cause CRS* and ICANS*, while Rituxan can cause serious heart, skin, kidney, and bowel problems and infusion-related reactions.

To learn more about how the side effects of these treatments compare, talk with your doctor.

* To learn more about this side effect, see the “Side effects explained” section below.

Does Epkinly cause long-term side effects?

It’s possible. Long-term side effects include those that may start any time during treatment with a drug, even if you’ve been receiving it for a long time. They also include side effects that may not go away, even after you stop treatment.

Examples of long-term side effects reported in Epkinly’s studies include:

  • low white blood cell count, which can increase the risk of infection
  • low red blood cell count, which can cause tiredness and shortness of breath
  • low platelet count, which can cause bruising or bleeding problems

These side effects can continue for as long as you receive Epkinly injections. They may also last a long time after you’ve stopped treatment with this medication.

Talk with your doctor to learn more about possible side effects of Epkinly and how long they may last.

Learn more about some of the side effects Epkinly may cause.

Risk of CRS

Epkinly has a boxed warning about the risk of CRS. A boxed warning is the most serious warning from the FDA. It alerts doctors and patients about drug effects that may be dangerous.

CRS was a common side effect reported in studies of Epkinly. CRS is usually mild, but in rare cases it can be severe or even life threatening.

CRS occurs when high levels of immune system proteins called cytokines are released in your body. Cytokines can cause inflammation in tissues and organs throughout your body, which can disrupt normal bodily functions.

CRS may cause symptoms such as:

CRS typically occurs within 24 hours of receiving a dose of Epkinly. It’s most likely to occur with the first four doses, especially with the third dose (which is the first full dose). Symptoms of CRS usually improve within a few days.

What might help

To help prevent CRS, your doctor will increase your Epkinly dose slowly over your first three doses. They’ll also prescribe medications to help prevent CRS before each of your first four Epkinly doses.

For example, you may be given:

If you have CRS with any of your first four Epkinly doses, your doctor may also prescribe these preventive medications before future doses.

Additionally, you’ll need to stay in the hospital for 24 hours after receiving your third dose of Epkinly (since this will be your first full dose and the most likely dose to cause CRS). This allows healthcare professionals to monitor you and treat any CRS symptoms if needed.

If you have symptoms of CRS after receiving any other dose of Epkinly, tell your doctor. They’ll decide whether you need treatment in a hospital. You shouldn’t drive or operate machinery until your symptoms have fully resolved.

If you have CRS, your doctor may delay your next Epkinly dose until your symptoms improve. But if you have severe CRS, your doctor will likely recommend stopping Epkinly treatment.

Risk of ICANS

Epkinly has a boxed warning about the risk of ICANS. A boxed warning is the most serious warning from the FDA.

ICANS was a common side effect reported in studies of Epkinly. It causes symptoms that affect your brain and nerves. It’s usually mild, but in rare cases it can be severe or even life threatening. ICANS may cause symptoms such as:

  • tiredness or sleepiness
  • confusion
  • memory problems
  • trouble writing or speaking
  • trouble understanding spoken or written words
  • muscle weakness
  • tremor
  • seizure

ICANS can occur within 2 weeks of receiving a dose of Epkinly and is most likely to occur with the first four doses. Symptoms of ICANS usually improve after a few days.

What might help

If you have symptoms of ICANS after receiving a dose of Epkinly, tell your doctor. They’ll decide whether you need treatment in a hospital. You shouldn’t drive or operate machinery until your symptoms have fully resolved.

If you have ICANS, your doctor may delay your next Epkinly dose until your symptoms improve. But if you have severe ICANS, your doctor will likely recommend stopping Epkinly treatment.

Allergic reaction

Like most drugs, Epkinly can cause an allergic reaction in some people. But this side effect wasn’t reported in the drug’s studies. Symptoms can be mild to serious and can include:

  • skin rash
  • itchiness
  • flushing (temporary warmth, redness, or deepening of skin color)
  • swelling under your skin (usually in your eyelids, lips, hands, or feet)
  • swelling of your mouth, tongue, or throat, which can make it hard to breathe

What might help

If you have mild symptoms of an allergic reaction, such as a mild rash, call your doctor right away. They may suggest a treatment to manage your symptoms. Examples include:

  • an antihistamine you swallow, such as Benadryl (diphenhydramine)
  • a product you apply to your skin, such as hydrocortisone cream

If your doctor confirms you’ve had a mild allergic reaction to Epkinly, they’ll decide whether you should continue treatment.

If you have symptoms of a severe allergic reaction, such as swelling or trouble breathing, call 911 or your local emergency number right away. These symptoms could be life threatening and require immediate medical care.

If your doctor confirms you’ve had a serious allergic reaction to Epkinly, they may have you switch to a different treatment.

Keeping track of side effects

During your Epkinly treatment, consider taking notes on any side effects you’re having. You can then share this information with your doctor. This is especially helpful when you first start a new drug or combination of treatments.

Your side effect notes can include things such as:

  • what dose of the drug you were receiving when you had the side effect
  • how soon you had the side effect after starting that dose
  • what your symptoms were
  • how your symptoms affected your daily activities
  • what other medications you were taking
  • any other information you feel is important

Taking notes and sharing them with your doctor will help them learn more about how Epkinly affects you. They can then use this information to adjust your treatment plan if needed.

Below is important information you should consider before starting treatment with Epkinly.

Boxed warnings

Epkinly has boxed warnings about the risk of CRS and ICANS. Boxed warnings are the most serious warnings from the FDA.

Risk of CRS: Epkinly can cause CRS, which is a side effect caused by high levels of inflammatory proteins called cytokines in your body. It can be severe or even life threatening.

Risk of ICANS: Epkinly can cause ICANS, which is a side effect affecting your brain and nerves. It can be severe or even life threatening.

To learn more, see the “Side effects explained” section above.

Other warnings

Epkinly can sometimes cause harmful effects in people with certain conditions. This is known as a drug-condition interaction. Other factors may also affect whether Epkinly is a good treatment option for you.

Talk with your doctor about your health history before starting this drug. Be sure to tell them if any of the following factors apply to you:

  • severe kidney or liver problems
  • infection
  • past allergic reaction to Epkinly
  • pregnancy
  • breastfeeding

Alcohol and Epkinly

There are no known interactions between alcohol and Epkinly. But if you have certain side effects with Epkinly, such as headache, nausea, or diarrhea, drinking alcohol could make them worse.

If you have questions about consuming alcohol during Epkinly treatment, talk with your doctor or pharmacist.

Pregnancy and breastfeeding with Epkinly

Epkinly is usually prescribed for someone who is pregnant or breastfeeding only if the benefits of treatment outweigh the potential risks to the fetus or child.

Pregnancy

Epkinly is not safe during pregnancy. If you’re pregnant or planning to become pregnant, talk with your doctor about your treatment options.

If you’re able to become pregnant, your doctor may recommend using birth control during your Epkinly treatment and for 4 months afterward.

Breastfeeding

Epkinly is not safe to receive while breastfeeding. You should not breastfeed during Epkinly treatment and for 4 months after treatment ends. If you’re breastfeeding or planning to do so, talk with your doctor about your options.

Like most drugs, Epkinly can cause a number of side effects that range from mild to serious. But most are temporary and go away after a few days to weeks. If you have questions about side effects Epkinly can cause, talk with your doctor. Examples of questions to help get you started include:

  • How can I prevent infection during Epkinly treatment?
  • What monitoring for side effects will I need during treatment?
  • Do other treatment options for my condition cause similar side effects?

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Disclaimer: Healthline 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.