Imfinzi (durvalumab) is a prescription brand-name medication. It’s approved by Food and Drug Administration (FDA) to treat certain types of bladder cancer and lung cancer.

Specifically, Imfinzi can be used to treat:

Imfinzi is a type of immunotherapy that helps your immune system attack cancer cells. For treating NSCLC, Imfinzi is meant to be used for a maximum of 1 year. For treating other types of cancer, your doctor will give you more information about how long you may use this drug.

Here are some fast facts on Imfinzi:

  • Active ingredient: durvalumab, which is a biologic
  • Drug class: PD-L1 inhibitors
  • Drug form: liquid solution given as an intravenous (IV) infusion
  • FDA approval year: 2017

Like other medications, Imfinzi can cause side effects. Read on to learn about potential common, mild, and serious side effects. For a general overview of Imfinzi, including details about its uses, see this article.

Imfinzi can cause certain side effects, some of which are more common than others. These side effects are usually temporary, lasting a few days or weeks. But if the side effects last for 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 Imfinzi in clinical trials. The side effects can vary depending on the condition the drug is being used to treat.

More common side effects in people taking Imfinzi for urothelial cancer include:

More common side effects in people using Imfinzi for non-small cell lung cancer include:

More common side effects in people using Imfinzi for small cell lung cancer include:

  • fatigue
  • hair loss (see “Side effect specifics” below)
  • nausea

Below are some mild side effects of Imfinzi. This list doesn’t include all possible side effects of the drug. For more information, refer to Imfinzi’s medication guide.

Mild side effects of Imfinzi can include:

These side effects are usually temporary, lasting a few days or weeks. But if the side effects last for 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 the side effects the drug causes. If you develop a side effect while using Imfinzi and want to tell the FDA about it, visit MedWatch.

Imfinzi may cause serious side effects, but this isn’t common. The list below may not include all possible serious side effects of the drug. For more information, refer to Imfinzi’s medication guide.

If you develop serious side effects while using Imfinzi, 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 and their symptoms can include:

  • infusion reactions (see “Side effect specifics” below)
  • immune system reactions (see “Side effect specifics” below)
  • serious infection (see “Side effect specifics” below)
  • allergic reaction (see “Side effect specifics” below)

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

Is joint pain a side effect of Imfinzi?

Joint pain wasn’t reported as a side effect in clinical trials of Imfinzi.

But Imfinzi may cause inflammation (damage and swelling) in your body, which can affect your joints and cause pain.

If you have joint pain while using Imfinzi, talk with your doctor. They may be able to recommend treatments to help you feel better. Or, they may suggest a different medication for your condition.

Will I need to be observed for side effects after Imfinzi infusions?

Imfinzi is given as an intravenous (IV) infusion, but you probably won’t need to stay for observation after receiving a dose.

Imfinzi may cause infusion reactions, such as dizziness or fainting, but these usually occur while you receive the drug. A healthcare provider will monitor you during the infusion to treat any reactions you develop.

Some drugs given by infusion can cause infusion-related reactions hours or even days after the infusion. But this hasn’t been reported with Imfinzi.

If you have any concerns about infusion reactions from Imfinzi, talk with your doctor.

How long can Imfinzi side effects last?

How long Imfinzi side effects last can vary from person to person. Following your last dose of the drug, Imfinzi can stay in your system for about 3 months. This is the length of time it takes for your body to break down and clear most of the drug. Most side effects may go away before then. But some people may experience side effects after stopping treatment until the drug clears from the body.

If you’re concerned about how long you may have certain side effects of Imfinzi, talk with your doctor.

Learn more about some of the side effects that Imfinzi may cause.

Hair loss

Hair loss may occur with Imfinzi use. This was one of the more common side effects reported in clinical trials of the drug.

Hair loss may also be a symptom of low levels of thyroid hormones, which is another potential side effect of Imfinzi.

In addition, hair loss is a common side effect of chemotherapy drugs. Imfinzi isn’t a type of chemotherapy, but it may be used with chemotherapy medications to treat cancer.

What you can do

Talk with your doctor if you’re concerned about or experience hair loss while using Imfinzi. They can help determine the cause.

If your hair loss is related to hormone problems, your doctor may recommend medication to help regulate your hormone levels. Or, they may suggest that you try a different drug to treat your cancer.

Infusion reactions

Imfinzi is given as an intravenous (IV) infusion, which is an injection of medication into a vein over a period time. Imfinzi infusions usually take 1 hour. In clinical trials of Imfinzi, there were reports of reactions that occurred during infusions. This included severe infusion reactions in rare cases.

Infusion reactions can also be life threatening. Symptoms of severe infusion reactions can include:

What you can do

If you experience an infusion reaction while receiving a dose of Imfinzi, the healthcare provider will typically slow down or stop the infusion. Depending on the severity of your reaction, they may give you medications or other treatments to ease the side effects.

Your doctor may also want you to receive your next infusion more slowly than the previous one. Giving the infusion over a longer period of time may lower your risk for having another infusion reaction.

If your infusion reaction is severe, your doctor may have you stop treatment with Imfinzi and try a different medication for your cancer.

Immune system reactions

In rare cases, Imfinzi may cause the immune system to mistakenly attack the body’s healthy cells. This can lead to inflammation (damage and swelling) in any part of the body. In some cases, the immune system reactions can be severe or life threatening. Symptoms can vary depending on which part of your body is affected. These reactions weren’t common in clinical trials.

The following are some serious immune system side effects that Imfinzi may cause:

  • Colitis (inflammation of the bowel). Symptoms can include:
    • severe belly pain
    • blood in your mucus or stool
  • Hepatitis (inflammation of the liver). Symptoms can include:
    • pain on the right side of your belly
    • jaundice (a yellowing of the whites of the eyes and the skin)
  • Hormone problems, including thyroid disorders. Symptoms can include:
    • weight gain or loss
    • feeling hot or cold
    • feeling unusually tired
  • Nephritis (inflammation of the kidneys). Symptoms can include:
    • blood in your urine
    • producing less urine than usual
    • decreased appetite
  • Pneumonitis (inflammation of the lungs). Symptoms can include:
    • chest pain

What you can do

During your Imfinzi treatment, your doctor will monitor you for any inflammation or immune system reactions by ordering lab tests. These may include blood and urine tests.

If you have symptoms of an immune system reaction while using Imfinzi, talk with your doctor right away. Depending on which part of your body is affected, they may recommend treatment to help ease the inflammation. Your doctor may also decide to pause your Imfinzi treatment. Or, they may have you stop using Imfinzi and try a different treatment for your cancer.

Serious infections

Serious infections, such as pneumonia and cystitis, may occur during Imfinzi treatment, but this isn’t common. In clinical trials, people receiving Imfinzi were more likely to develop a serious infection, including pneumonia, than people receiving a placebo. (A placebo is a treatment without an active drug.)

Symptoms of pneumonia and other serious infections can include:

  • cough
  • fever
  • flu-like symptoms, such as shortness of breath or a runny or stuffy nose

Symptoms of cystitis can include:

  • blood in the urine
  • pain in the pubic bone, lower back, or belly area
  • a burning feeling when urinating
  • urinating more often than usual

What you can do

While using Imfinzi, talk with your doctor if you notice any symptoms of an infection. They can order tests to determine which type of infection you have. Your doctor can also recommend treatment to help ease your symptoms and clear up the infection.

In addition, you can take the following steps to help lower your risk for infection:

  • Wash your hands often using soap and warm water.
  • Avoid touching your face, especially your mouth, nose, and eyes.
  • Don’t share personal items, such as a toothbrush, washcloth, or cell phone.

Allergic reaction

As with most drugs, Imfinzi can cause an allergic reaction in some people. Symptoms can be mild or serious and can include:

  • rash
  • itching
  • flushing (warmth, swelling, or redness in your skin)
  • swelling under your skin, typically in your lips, eyelids, feet, or hands
  • 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 Imfinzi. But 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 use Imfinzi. This drug may not be the right treatment for you if you have certain medical conditions or other factors that affect your health. The conditions and factors to consider include the following:

Allergic reaction. You shouldn’t use Imfinzi if you’ve ever had an allergic reaction to it or any of its ingredients. Talk with your doctor about which other treatments are better choices for you.

Autoimmune disease. Imfinzi can cause your immune system to attack healthy cells, so the drug could make existing autoimmune diseases worse. (Lupus and Crohn’s disease are examples of autoimmune diseases.) Before you start Imfinzi treatment, tell your doctor about any autoimmune diseases you may have. They can determine whether Imfinzi is the best medication for your cancer.

Breathing problems. Taking Imfinzi may cause damage to your lungs. If you have or have ever had any breathing problems, using this drug may worsen the condition. Before you start Imfinzi treatment, tell your doctor if you have a history of any breathing problems. They can determine whether Imfinzi or a different drug is the right option for you.

Previous radiation treatment. Non-small cell lung cancer is sometimes treated with radiation. Having radiation before receiving Imfinzi may increase your risk for serious inflammation of the lungs. If you’ve received radiation to the chest area, tell your doctor before you use Imfinzi. They may want you to delay using the medication until the effects of the radiation have worn off.

Organ transplant. Imfinzi can cause your immune system to attack healthy cells. This includes cells in organs such as your lungs, kidneys, liver, and heart. This could be especially dangerous if you’ve had an organ transplant. Before you start using Imfinzi, be sure to tell your doctor if you’ve received an organ transplant.

Current infection. Some infections need time to clear up before it’s safe to start Imfinzi treatment. If you have a current infection and are receiving treatment for it, tell your doctor before you use Imfinzi. They can advise you on when to start using the drug.

Alcohol use with Imfinzi

There aren’t any known interactions between using Imfinzi and consuming alcohol. But drinking alcohol could worsen certain side effects of Imfinzi, such as nausea or fatigue (lack of energy).

If you drink alcohol, be sure to talk with your doctor before using Imfinzi. They can determine how much is safe for you to consume during your treatment.

Pregnancy and breastfeeding while using Imfinzi

It isn’t safe to use Imfinzi while pregnant. Studies of pregnant animals given Imfinzi found that the drug could cause miscarriage or stillbirth. If you’re pregnant or planning to become pregnant, talk with your doctor. They can recommend a treatment other than Imfinzi.

Keep in mind that if you’re using Imfinzi and are able to become pregnant, you should use birth control during your treatment. You should keep using it for 3 months or more after your last dose of the medication.

Also, there’s no information on the safety of Imfinzi while breastfeeding. It’s recommended that you don’t breastfeed during your Imfinzi treatment and for at least 3 months after your final dose of the drug. You should talk with your doctor if you’re thinking about breastfeeding. They can advise you on whether Imfinzi is right for you.

Side effects can occur while using Imfinzi, but they’re usually mild. Most mild side effects of the drug go away with time and don’t require medical attention.

It’s important to note that Imfinzi may be used on its own to treat cancer. It may also be used with chemotherapy. Some side effects of chemotherapy drugs and Imfinzi overlap, but the medications can also cause different side effects. Your doctor or pharmacist can help explain similarities and differences in side effects you may expect from each drug.

You should contact your doctor if you have any symptoms of an infusion reaction, immune system reaction, infection, or allergic reaction. These side effects could be serious and require medical attention.

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

For more information on bladder cancer, see our cancer articles. And to learn more about lung cancer, read our lung cancer articles.

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 other 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.