If you have a certain type of cancer, your doctor may prescribe Keytruda.

It’s a prescription drug that’s used in adults and some children with certain advanced forms of the following types of cancer:

To learn more about Keytruda and how it’s used to treat these types of cancer, see the “What is Keytruda used for?” section below.

Keytruda basics

Keytruda comes as a solution that your doctor will inject into your vein over a period of time.

It contains the active drug pembrolizumab, which is a type of cancer treatment called immunotherapy.

Pembrolizumab is a biologic medication. Biologics are made from parts of living organisms.

Keytruda isn’t available in a biosimilar form. (Biosimilars are like generic drugs. But unlike generics, which are made for non-biologic drugs, biosimilars are made for biologic drugs.) Instead, pembrolizumab comes only as the brand-name drug Keytruda.

Read on to learn more about Keytruda’s side effects, uses, cost, and more.

Like most drugs, Keytruda may cause mild or serious side effects. The lists below describe some of the more common side effects that Keytruda may cause. These lists don’t include all possible side effects.

Keep in mind that side effects of a drug can depend on:

  • your age
  • other health conditions you have
  • other medications you may be taking

Your doctor or pharmacist can tell you more about the potential side effects of Keytruda. They can also suggest ways to help reduce side effects.

Mild side effects

Here’s a short list of some of the mild side effects that Keytruda can cause. To learn about other mild side effects, talk with your doctor or pharmacist, or read Keytruda’s medication guide.

Mild side effects of Keytruda that have been reported include:

Mild side effects of many drugs may go away within a few days or a couple of weeks. But if they become bothersome, talk with your doctor or pharmacist.

* For more information on this side effect, see the “Side effect focus” section below.

Serious side effects

Serious side effects from Keytruda can occur, but they aren’t common. If you have serious side effects from Keytruda, call your doctor right away. But if you think you’re having a medical emergency, you should call 911 or your local emergency number.

Serious side effects of Keytruda that have been reported include:

* For more information on this side effect, see the “Side effect focus” section below.

Side effect focus

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

Rash

Rash is a side effect of immunotherapy drugs, including Keytruda.

Keytruda activates your immune system. (This is how the drug works to treat cancer.) But when your immune system is activated by Keytruda, your body may start attacking your skin.

Rashes caused by activating your immune system can be mild or severe.

Keytruda may cause a rash because of the way it activates your immune system. But it’s also possible to develop a rash just from getting infusions of Keytruda. (Infusions are injections of the drug given into your vein over a period of time.) Infusion-related reactions are described below.

What might help

Talk with your doctor if you develop a rash while you’re using Keytruda. Warning signs for a serious skin problem with Keytruda include:

  • blisters
  • peeling skin
  • painful sores in your mouth, nose, or genitals
  • fever
  • flu-like symptoms

Your doctor will check to see if your rash is caused by Keytruda or its infusions. They’ll also rate the severity of your rash.

If you develop a rash while you’re using Keytruda, your doctor might prescribe moisturizers to help hydrate and soften your skin. Sometimes, you’ll need to use either over-the-counter or prescription corticosteroids on your skin. But always check with your doctor before using any products on your rash.

If you develop a severe rash with Keytruda, your doctor may have you stop taking the drug. They may also prescribe corticosteroids that you’ll take by mouth.

Pneumonitis

Pneumonitis is inflammation in your lungs. It can occur in people using immunotherapy drugs, such as Keytruda.

Sometimes, it’s possible to develop pneumonitis after you stop taking Keytruda.

A variety of symptoms are seen with pneumonitis. In its early stages, some people may not have symptoms. Be sure to tell your doctor if you have:

  • a new or worsening cough
  • chest pain
  • shortness of breath
  • trouble breathing
  • fever

What might help

If you have pneumonitis with Keytruda, your doctor might prescribe corticosteroid treatment for you.

Additionally, your doctor may recommend that you temporarily or permanently stop taking Keytruda. If you need to temporarily stop taking Keytruda, your doctor may have you restart the drug after your symptoms reduce. But it’s possible you may develop pneumonitis again with Keytruda treatment.

Reactions related to infusion

Some people may react to infusions of Keytruda. (Infusions are injections of the drug given into your vein over a period of time.)

These reactions may be severe or life threatening. Infusion reactions can also cause severe allergic reactions. (See the section directly below for more information on allergic reaction.)

With an infusion reaction, you may experience:

What might help

During your Keytruda infusions, your doctor will closely monitor you for any symptoms of a reaction.

If you have symptoms of an infusion reaction, your doctor will first rate your symptoms from mild to life threatening.

For a severe or life threatening reaction, your doctor will stop your Keytruda infusion and have you permanently stop Keytruda treatment.

For a milder reaction, your doctor may slow the rate of your Keytruda infusion. Or they’ll stop the infusion and have you temporarily pause treatment with Keytruda.

Allergic reaction

Some people may have an allergic reaction to Keytruda.

Symptoms of a mild allergic reaction can include:

  • rash
  • itchiness
  • flushing (temporary warmth, redness, or deepening of skin color)

A more severe allergic reaction is rare but possible. Symptoms of a severe allergic reaction can include swelling under your skin, typically in your eyelids, lips, hands, or feet. They can also include swelling of your tongue, mouth, or throat, which can cause trouble breathing.

Call your doctor right away if you have an allergic reaction to Keytruda. But if you think you’re having a medical emergency, call 911 or your local emergency number.

If you have a certain type of advanced cancer, your doctor may prescribe Keytruda.

It’s a prescription drug that’s used for:

  • Lung cancer. Keytruda treats lung cancer that has spread from the lungs to other parts of the body. The two main types of lung cancer Keytruda treats are called non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). It’s used in adults as a:
    • first-choice treatment along with chemotherapy for non-squamous (cells of the outer lung) NSCLC that doesn’t have certain gene mutations (abnormal changes).
    • first-choice treatment along with chemotherapy for squamous (cells of the inner airway) NSCLC.
    • first-choice treatment for NSCLC that doesn’t have certain gene mutations in people who have a protein called programmed death ligand-1 (PD-L1).
    • first-choice treatment for NSCLC in people with PD-L1 who’ve already tried certain chemotherapy treatments.
    • treatment for SCLC in people who’ve already tried chemotherapy and at least one other therapy.*
  • Bladder cancer. Keytruda is used in adults to treat bladder cancer that’s:
    • advanced or has spread from the bladder to other parts of the body in people with PD-L1 who can’t use certain types of chemotherapy. Keytruda can also be used for this condition in people who aren’t able to take chemotherapy that contains platinum, even if they don’t have PD-L1.*
    • advanced or has spread from the bladder to other parts of the body in people who’ve used certain types of chemotherapy, but their cancer worsened.
    • a certain type called Bacillus Calmette-Guerin (BCG)-unresponsive, high-risk, non-muscle invasive bladder cancer (NMIBC). (NMIBC is cancer of the lining of your bladder. And BCG is a common treatment for NMIBC. But when the cancer doesn’t improve with BCG treatment, it’s considered to be BCG-unresponsive.)
  • Skin cancer. For skin cancer, Keytruda is used for:
    • a type called melanoma that can’t be removed by surgery or has spread from the skin to other parts of the body. For melanoma, Keytruda is given to adults.
    • melanoma that was removed by surgery, but is found in the lymph nodes. For melanoma, Keytruda is given to adults.
    • a type called Merkel cell carcinoma that’s recurring (came back after past treatment) or spreading from the skin to other parts of the body. For this use, Keytruda can be given to adults and children ages 6 months and older.*
    • a type called cutaneous squamous cell carcinoma that’s recurring or has spread to other parts of the body. For this use, Keytruda is given to adults when their cancer can’t be removed by surgery or with radiation.
  • Head and neck cancer. Keytruda is used in adults for head and neck cancer as a:
    • first-choice treatment together with certain chemotherapy drugs, if the cancer is spreading to other parts of the body, or recurring and can’t be removed by surgery.
    • first-choice treatment in people with PD-L1 whose cancer is spreading to other parts of the body, or recurring and can’t be removed by surgery.
    • treatment for cancer that’s recurring or spreading to other parts of the body and didn’t improve with certain chemotherapy drugs.
  • Certain types of lymphoma. Keytruda treats certain types of blood cancers called classical Hodgkin lymphoma (cHL) and primary mediastinal large B-cell lymphoma (PMBCL). For these blood cancers, Keytruda is used in:
    • adults with relapsed or refractory cHL. (With relapsed cHL, the disease improved with past treatment, but it stopped responding to treatment after 6 months. With refractory cHL, the disease didn’t improve with past treatment or it responded for fewer than 6 months.)
    • children ages 6 months and older with relapsed or refractory cHL. For this use, at least two other treatments must have already been tried.
    • adults and children ages 6 months and older with PMBCL who’ve tried two other treatments, but their cancer didn’t improve. But Keytruda isn’t used in people with PMBCL who need a type of treatment called cytoreductive therapy. (Cytoreductive treatment lowers the number of cancer cells.)
  • Stomach cancer.* Keytruda is used for stomach cancer that’s recurring or spreading from the stomach to other parts of the body in adults with PD-L1. For this use, at least two other treatments must have already been tried.
  • Esophageal cancer. Keytruda is used in adults to treat cancer of the esophagus that’s advanced or has spread from the esophagus to other parts of the body and can’t be removed by surgery. For this use, Keytruda can be used together with chemotherapy drugs. Or it can be used alone in people who’ve tried at least one other treatment and who have PD-L1.
  • Cervical cancer.* Keytruda treats cervical cancer that’s recurring or spreading from the cervix to other parts of the body. For this use, Keytruda is given to adults with PD-L1 who’ve already tried chemotherapy.
  • Uterine cancer.* Keytruda treats advanced uterine cancer that can’t be treated with radiation or surgery. For this use, Keytruda is given to adults who’ve already tried other treatments, but their cancer didn’t improve. And Keytruda is taken together with lenvatinib (Lenvima).
  • Liver cancer.* Keytruda is used for liver cancer in adults who’ve already tried treatment with sorafenib (Nexavar).
  • Kidney cancer. Keytruda is used in adults as a first-choice treatment for kidney cancer. It’s given together with axitinib (Inlyta).
  • Breast cancer.* Keytruda is used in adults together with chemotherapy to treat a type of breast cancer called triple-negative breast cancer. For this use, Keytruda is given for cancer that’s recurring but can’t be removed by surgery, or is spreading from the breast to other parts of the body. It’s also given to people with PD-L1.
  • Colon cancer and other solid tumors. Keytruda is used for colon cancer and other solid tumors that can’t be removed by surgery or are spreading from where they started to other parts of the body. This includes:
    • solid tumors that are microsatellite instability-high (MIH) or mismatch repair deficient (MRD) in adults and children ages 6 months and older. (These types of cancer have certain gene mutations.) Keytruda is given to people whose cancer didn’t improve with other treatments*
    • MIH or MRD colorectal cancer in adults and children ages 6 months and older whose cancer didn’t respond to other treatments*
    • first-choice treatment for MIH or MRD colorectal cancer in adults
    • solid tumors with certain gene mutations in adults and children ages 6 months and older. But Keytruda isn’t recommended for this use in children ages 6 months and older with brain cancer or spinal cord cancer*

Keytruda is an antibody (type of immune system protein). It helps your immune system detect cancer cells in your body and stop their growth. To learn more about how it works, see the first question below in the “What are some frequently asked questions about Keytruda?” section.

* For this use, Keytruda received accelerated approval from the Food and Drug Administration (FDA). Accelerated approval is based on information from early clinical studies. The FDA’s decision for full approval will be made after more studies are completed.

Find answers to some commonly asked questions about Keytruda.

How does Keytruda work? And what are signs that it’s working?

Keytruda’s mechanism of action is to promote the activity of your immune system to stop cancer cells from growing.

The drug attaches to a protein called programmed death receptor-1 (PD-1). Keytruda blocks the interaction of this protein with another protein called programmed death ligand-1 (PD-L1).

The interaction between these two proteins stops specific actions of your immune system. In some cancers, the interaction between PD-1 and PD-L1 is overactive, and your immune system can’t detect the cancer cells.

So by blocking the interaction between PD-1 and PD-L1, Keytruda reactivates your immune system. Then your immune system is able to detect cancer cells and stop them from growing and spreading.

If cancer cells stop growing, it’s a sign that Keytruda is working.

Talk with your doctor about how they’ll check to see if Keytruda is working for your cancer.

When will I need to stop using Keytruda?

Your doctor may have you stop Keytruda treatment early if:

  • your cancer isn’t responding well to Keytruda, or
  • you’re having bothersome or severe side effects from the drug

But, even if your cancer remains stable and you’re tolerating Keytruda’s side effects, your doctor may have you stop treatment after a certain amount of time. This is because the long-term effects of Keytruda aren’t known.

In studies, the length of Keytruda treatment was limited to about 2 to 3 years. But this depended on the type of cancer being treated.

Talk with your doctor to find out how long you might need to take Keytruda.

What’s Keytruda’s success rate in treating cancer?

Every person may have a different response to Keytruda.

Keytruda’s success rate can vary depending on:

  • the type of cancer that’s being treated
  • any other drugs you may be taking to treat cancer

In studies of Keytruda, researchers reported how long people lived and how long their cancer remained stable after starting Keytruda. If you’d like to know about these study results and the success rate of Keytruda for your type of cancer, talk with your doctor.

Is Keytruda a chemotherapy drug?

No, Keytruda isn’t a chemotherapy drug. It’s an immunotherapy drug.

Chemotherapy is a type of cancer treatment that kills cancer cells or stops them from multiplying (making more cells). Immunotherapy, on the other hand, works with your immune system to help your body fight off cancer cells.

If you’d like to know more about the difference between chemotherapy and immunotherapy, talk with your doctor.

Does Keytruda treat ovarian cancer or brain cancer such as glioblastoma?

Currently, Keytruda isn’t used to treat ovarian cancer.

Some studies have shown that Keytruda may be beneficial for a certain type of ovarian cancer. This was seen when Keytruda was used either alone or together with other cancer drugs. But more studies are needed to confirm Keytruda’s effectiveness and safety in treating ovarian cancer.

As described in the “What is Keytruda used for?” section above, Keytruda does treat solid tumors with a certain gene mutation that can’t be removed by surgery or are spreading. This could include certain types of brain cancer.

For this condition, the drug can be given to adults and children ages 6 months and older. But Keytruda isn’t recommended for children ages 6 months and older with brain cancer or spinal cord cancer that has a certain gene mutation.

A recent study showed that Keytruda isn’t beneficial for a type of advanced brain cancer called high-grade glioma. Another study showed that recurring glioblastoma (another form of brain cancer) isn’t improved with Keytruda treatment, given either alone or together with another cancer drug.

If you’d like to know more about treatment options for ovarian cancer or brain cancer, talk with your doctor.

Is Keytruda used for prostate or pancreatic cancer?

No, Keytruda isn’t currently used for prostate cancer or pancreatic cancer.

One study showed that Keytruda may be effective and safe for a specific type of prostate cancer called programmed death ligand 1 (PD-L1)-positive, metastatic castration-resistant prostate cancer. (PD-L1 is a type of protein. With metastatic prostate cancer, the cancer has spread from the prostate to other parts of the body. And with castration-resistant prostate cancer, the cancer doesn’t improve with treatment that lowers certain hormone levels.)

But more studies are still needed to look at treating prostate cancer with Keytruda.

For pancreatic cancer, recent studies have looked at using immunotherapy as treatment. (And keep in mind that Keytruda is an immunotherapy drug.) Researchers are currently studying a drug combination that includes pembrolizumab (the active drug in Keytruda) for advanced pancreatic cancer.

Talk with your doctor if you’re interested in treatment options for prostate cancer or pancreatic cancer.

Costs of prescription drugs can vary depending on many factors. These factors include what your insurance plan covers and which pharmacy you use.

If you have questions about how to pay for your prescription, talk with your doctor or pharmacist. You can also visit the Keytruda manufacturer’s website to see if it has support options.

Your doctor will explain how Keytruda is given. They’ll also explain how much will be given and how often. Be sure to follow your doctor’s instructions. Below are commonly used dosages, but always follow the dosage your doctor prescribes.

Receiving Keytruda

Keytruda comes as a solution that your doctor will inject into your vein over a period of time. This type of injection is called an intravenous (IV) infusion.

Your IV infusions of Keytruda will each be given over about 30 minutes.

Dosage

Depending on the type of cancer you have, your doctor will prescribe the dose of Keytruda that’s right for you. You’ll take the drug once every 3 weeks or once every 6 weeks.

Children taking Keytruda will receive a dose once every 3 weeks.

Receiving Keytruda with other drugs

You might need to take Keytruda with other medications, depending on the type of cancer you have. Examples of other drugs that may be given with Keytruda include:

  • axitinib (Inlyta)
  • lenvatinib (Lenvima)
  • pemetrexed (Alimta)
  • chemotherapy that’s made with platinum
  • fluoropyrimidine-based chemotherapy
  • carboplatin (Paraplatin)
  • paclitaxel (Pacitaxel)
  • paclitaxel protein-bound (Abraxane)
  • fluorouracil

Questions about receiving Keytruda

Here are answers to some common questions about receiving Keytruda.

  • What if I miss a dose of Keytruda? You’ll receive Keytruda at your doctor’s office or an infusion clinic. If you miss an appointment for your dose, call the office or clinic to reschedule your appointment. Missing doses of Keytruda may lower your body’s response to the drug.
  • Will I need to use Keytruda long term? Depending on the type of cancer you have and your body’s response to Keytruda, your doctor will tell you how many doses of Keytruda you’ll need. The long-term effects of Keytruda aren’t yet known. In studies, treatment length was limited to up to 3 years. Your doctor may have you stop treatment early if your cancer worsens or if you have bothersome or severe side effects of Keytruda.
  • Should I take Keytruda with food? You’ll receive Keytruda as an injection into your vein. So how well your body absorbs the drug doesn’t depend on whether you receive it with a full or empty stomach. Talk with your doctor if you have questions about eating around the times you receive Keytruda doses.
  • How long does Keytruda take to work? Keytruda can start working right away to promote your immune system’s activity. (This is how the drug works to treat cancer.) But it’s not known how long your immune system’s activity needs to be stimulated in order for the drug to treat your cancer. How long Keytruda takes to work may also depend on any other cancer medications you’re taking. Every few weeks or months your doctor will check to see how well your cancer is responding to Keytruda.
Questions for your doctor

You may have questions about Keytruda and your treatment plan. It’s important to discuss all your concerns with your doctor.

Here are a few tips that might help guide your discussion:

  • Before your appointment, write down questions like:
    • How will Keytruda affect my body, mood, or lifestyle?
  • Bring someone with you to your appointment if doing so will help you feel more comfortable.
  • If you don’t understand something related to your condition or treatment, ask your doctor to explain it to you.

Remember, your doctor and other healthcare professionals are available to help you. And they want you to get the best care possible. So don’t be afraid to ask questions or offer feedback on your treatment.

Keytruda and Opdivo are both used for certain types of cancer. But Opdivo has fewer uses than Keytruda does.

Opdivo can be used for:

To see a list of Keytruda’s uses, see the “What is Keytruda used for?” section above.

Like Keytruda, Opdivo is a programmed death receptor-1 blocking antibody (type of immune system protein). These drugs help your immune system detect cancer cells in your body and stop their growth.

To see an in-depth comparison of these two drugs, see this drug article. And be sure to talk with your doctor if you have questions about which drug is right for you.

Some important things to discuss with your doctor when considering treatment with Keytruda include:

  • your overall health
  • any medical conditions you may have

Also tell your doctor about any other medications you’re taking. This is important to do because some drugs interfere with Keytruda.

These and other considerations to discuss with your doctor are described below.

Interactions

Taking medications, vaccines, foods, and other things with a certain drug can affect how the drug works. These effects are called interactions.

Before taking Keytruda, be sure to tell your doctor about all medications you take (including prescription and over-the-counter types). Also describe any vitamins, herbs, or supplements you use. Your doctor or pharmacist can tell you about any interactions these items may cause with Keytruda.

Interactions with drugs or supplements

So far, there aren’t any known interactions between Keytruda and other medications, vitamins, herbs, or supplements.

But to be safe, talk with your doctor or pharmacist about any drugs, vitamins, herbs, or supplements you may want to start taking.

Warnings

Keytruda may not be right for you if you have certain medical conditions or other factors that affect your health. Talk with your doctor about your health history before you take Keytruda. Factors to consider include those in the list below.

  • A certain type of transplant. If you’ve received a type of transplant called an allogenic hematopoietic stem cell transplant before or after taking Keytruda, you may develop serious or life threatening complications. (With this type of transplant, you receive stem cells given by someone else, called a donor. This is unlike an autologous transplant, in which you receive stem cells taken from your own body at an earlier time.) Be sure to talk with your doctor if you’ve had or are planning to have a stem cell transplant.
  • Allergic reaction. If you’ve had an allergic reaction to Keytruda or any of its ingredients, you shouldn’t take Keytruda. Ask your doctor what other medications are better options for you.
  • Use of certain multiple myeloma treatments. Your doctor won’t recommend Keytruda for you if you have multiple myeloma and you’re taking a thalidomide-like drug along with dexamethasone. This three-drug combination is used only in studies because of the risk of life threatening complications. If you have multiple myeloma, be sure and talk with your doctor about the treatments you’re using for it before taking Keytruda.

Use with alcohol

Some medications interact with alcohol. Keytruda isn’t one of them.

Before starting Keytruda, ask your doctor or pharmacist if it’s safe for you to drink alcohol.

Pregnancy and breastfeeding

Keytruda is dangerous if it’s given to a pregnant person. In fact, it can harm a developing fetus. This is because with Keytruda, your immune system may not recognize the fetus. And your immune system can start to attack the fetus’ cells.

During treatment with Keytruda, your doctor may recommend that you use birth control to help prevent pregnancy. You might also need to continue using birth control for up to 4 months following your last dose of the drug.

It’s not known for sure whether Keytruda passes into breast milk. If Keytruda does pass through breast milk, it’s not known whether it would be harmful to a child who is breastfed.

It’s recommended that you avoid breastfeeding during and for up to 4 months after stopping Keytruda treatment. If you have questions about this, talk with your doctor.

If you have questions about taking Keytruda, talk with your doctor or pharmacist. They can tell you about other treatments for your condition.

Here’s a list of articles you might find interesting:

Additionally, some questions to ask your doctor about Keytruda treatment may include:

  • Will Keytruda cure my cancer?
  • Will I lose my hair if I’m taking Keytruda?
  • If I have ovarian cancer, can I register for a study with Keytruda?
  • If I stop taking Keytruda because of side effects, will may cancer get worse?

You can also learn more about breast cancer and the use of Keytruda in treating it by subscribing to Healthline’s breast cancer newsletter.

Q:

What are the warning signs of a severe rash caused by Keytruda?

Anonymous patient

A:

Rash is a common side effect of Keytruda. But certain types of rashes may be a symptom of more severe side effects, including:

Symptoms that are warning signs your rash may be severe include:

  • fever
  • blistering or peeling of your skin
  • joint pain and aching
  • cough that produces mucous
  • burning or stinging in your eyes

If you have a rash along with any of these symptoms, or if your rash doesn’t go away after a day or two, tell your doctor. They can check your rash and recommend if treatment is needed.

Victor Nguyen, PharmD, MBAAnswers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.
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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 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.

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