Tzield (teplizumab-mzwv) is a prescription biologic drug used to delay the worsening of type 1 diabetes. Tzield can cause side effects that range from mild to serious, including headache and skin rash.

Specifically, Tzield is a biological product used in adults and children ages 8 years and older to slow the progress of type 1 diabetes from Stage 2 to Stage 3.

The active ingredient in Tzield is teplizumab-mzwv.* (An active ingredient is what makes a drug work.) The drug comes as a liquid solution. It’s given as an intravenous (IV) infusion (an injection into a vein given over time) by a healthcare professional.

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

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

Some people may experience mild to serious side effects during Tzield 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 Tzield. These include:

  • nausea
  • diarrhea
  • headache
  • skin rash
  • elevated liver enzyme levels
  • common cold symptoms
  • mild allergic reaction*

In most situations, these side effects won’t last long. And you may be able to manage some of them easily with diet changes and over-the-counter medications. But if you have ongoing or bothersome symptoms, talk with your doctor or pharmacist. And do not stop Tzield treatment unless your doctor recommends it.

Tzield 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.

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

If you develop serious side effects from Tzield 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.

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 Tzield, visit MedWatch.

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

Is Tzield safe for older adults?

Stage 2 type 1 diabetes mostly occurs in children and young adults. Because of this, Tzield wasn’t studied in older adults (ages 65 years and over). However, older adults have a higher risk of a weakened immune system, and Tzield may increase that risk. Talk with your doctor about your treatment options if you’re age 65 years or older.

Will Tzield cause harm to my liver?

Studies of Tzield showed increases in liver enzymes. Because of this, your doctor will order a liver function test for you before you start Tzield treatment. If your test results show elevated liver enzyme levels, Tzield therapy is not recommended.

Your doctor will continue ordering liver enzyme tests throughout your Tzield treatment. Some people will have increased liver enzyme levels, especially during the first 5 days of treatment. If these levels get too high, your doctor will likely have you stop Tzield. However, most liver enzyme levels return to usual 1–2 weeks after treatment ends.

With these precautions in place, harm to your liver is unlikely. Talk with your doctor or pharmacist if you have concerns about elevated liver enzymes from this medication.

Does Tzield cause long-term side effects?

It’s unlikely since Tzield treatment only lasts for 14 days. Long-term side effects weren’t reported in studies of Tzield. If you’re concerned about possible long-term side effects from this medication, talk with your doctor or pharmacist.

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

Cytokine release syndrome

Cytokine release syndrome (CRS), an over-activation of the immune system also called “cytokine storm,” was an occasional side effect reported in studies of Tzield. CRS may cause symptoms such as:

Most of the time, CRS occurs within the first 5 days of treatment and may happen up to 28 days after completing treatment with the medication. Additional factors that can increase the risk of CRS during Tzield treatment include:

  • obesity
  • heart disease
  • diabetes
  • weakened immune system
  • residence in a nursing or group facility
  • being age 65 years or over

What might help

If you have risk factors for CRS during Tzield treatment, your doctor will likely prescribe medications for fever, allergies, and nausea. These will be given approximately 1 hour before your infusion* for at least the first five doses, then as needed.

* Tzield comes as a liquid solution given as an intravenous (IV) infusion (an injection into a vein given over time) by a healthcare professional.

Low white blood cell, red blood cell, and platelet counts

Low counts of white blood cells, red blood cells, and platelets were occasional side effects reported in studies of Tzield. The symptoms of low blood cell and platelet counts include:

  • weakness
  • dizziness
  • fatigue (low energy)
  • ashen, yellow, or pale skin color
  • shortness of breath
  • unusual bleeding or bruising, such as nosebleeds
  • fever or chills
  • cough
  • sore throat
  • pain when urinating
  • mouth ulcers
  • wounds that won’t scab or heal

What might help

Before starting Tzield, your doctor will order blood tests to determine whether you have enough blood cells and platelets to begin treatment. They’ll have these tests run daily during your Tzield treatment and have you stop the medication if your counts are too low. Most white blood cell levels return to usual after 5 days of treatment.

Because having a low level of white blood cells may increase your risk of infection, your doctor may recommend eating carefully cooked foods. They may have you avoid products such as raw or undercooked meat, dairy, eggs, and vegetables. Keeping your hands and surfaces sanitized will also help to reduce your risk of infection during Tzield treatment.

Allergic reaction

Like most drugs, Tzield can cause an allergic reaction in some people. 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 Tzield, 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 Tzield, they may have you switch to a different treatment.

Keeping track of side effects

During your Tzield 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 taking a new drug or using a combination of treatments.

Your side effect notes can include things such as:

  • what dose of the drug you were taking 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

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

Below is important information you should consider before starting Tzield treatment.


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

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

Alcohol and Tzield

There are no known interactions between alcohol and Tzield. If you have questions about consuming alcohol during Tzield treatment, talk with your doctor or pharmacist.

Pregnancy and breastfeeding with Tzield

Tzield is usually prescribed for someone who’s pregnant or breastfeeding only if the benefits of treatment outweigh the potential risks to them and the fetus or child.


You should not receive Tzield if you’re pregnant or plan to become pregnant within 30 days of your treatment ending. Although studies of Tzield did not evaluate its safety when received during pregnancy, it’s believed Tzield may harm a fetus. This is because it belongs to a group of drugs called monoclonal antibodies that can pass into the placenta. These drugs may cause weakening of the immune system in an infant who was exposed to the drug as a fetus.

If you’re able to become pregnant, your doctor may recommend using a form of birth control during your Tzield treatment.

If you receive this drug while pregnant, consider calling Provention Bio’s Adverse Eventreporting line at 844-778-2246. This registry collects information about the safety of Tzield when received during pregnancy.

If you’re pregnant or planning to become pregnant, talk with your doctor about your treatment options.


Tzield treatment may not be safe while breastfeeding. Studies did not determine how Tzield affects milk production or whether it passes into breast milk. And it’s not known whether it might cause harm to a child who’s breastfed.

The manufacturer of Tzield recommends the option of pumping milk and discarding it during Tzield treatment and for up to 20 days after treatment ends.

If you’re breastfeeding or planning to do so, talk with your doctor about your options.

Like most drugs, Tzield can cause several 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 Tzield can cause, talk with your doctor. Examples to help get you started include:

  • What is my risk of developing side effects from Tzield?
  • How long are side effects likely to last?
  • What over-the-counter medications should I have on hand to help manage Tzield side effects?
  • What can I do to help reduce or prevent side effects from this medication?

To learn more about Tzield, see these articles:

To get information on different conditions and tips for improving your health, subscribe to any of Healthline’s newsletters. You may also want to check out the online communities at Bezzy. It’s a place where people with certain conditions can find support and connect with others.

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.