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Keytruda

pembrolizumab
Used for Non-Hodgkin Lymphoma, Hodgkin Lymphoma, Lung Cancer, Breast Cancer, Stomach Cancer, Skin Cancer, Melanoma, Colon Cancer, Renal Cancer, Bladder Cancer, Cervical Cancer, Uterine Cancer, Liver Cancer
Used for Non-Hodgkin Lymphoma, Hodgkin Lymphoma, Lung Cancer, Breast Cancer, Stomach Cancer, Skin Cancer, Melanoma, Colon Cancer, Renal Cancer, Bladder Cancer, Cervical Cancer, Uterine Cancer, Liver Cancer

Keytruda (pembrolizumab) is an immunotherapy medication that’s used to treat many different types of cancer, including non-small cell lung cancer (NSCLC), breast cancer, and melanoma. This medication turns on your immune system so it can attack cancer cells. It's given as an intravenous (IV) infusion at a medical office or infusion center. Sometimes, Keytruda (pembrolizumab) can cause side effects, like diarrhea, rash, and trouble breathing, that might need to be treated with corticosteroids. Depending on the cancer, your treatment plan can consist of Keytruda (pembrolizumab) by itself or with other anticancer therapy.

Last reviewed on February 12, 2024
basics-icon

What is Keytruda (pembrolizumab)?

What is Keytruda (pembrolizumab) used for?

How Keytruda (pembrolizumab) works

Your immune system helps protect you from harm in many ways. For example, it can attack and kill cancer cells that it recognizes as abnormal. But some cancer cells can hide from your immune system using a process called the programmed death-1 (PD-1) pathway. When this happens, your immune system can’t find and attack the cancer cells as well, so the cancer can grow.

Keytruda (pembrolizumab) is an immunotherapy medication that blocks the PD-1 pathway. It’s also called a PD-1 inhibitor or checkpoint inhibitor.

By blocking the PD-1 pathway, Keytruda (pembrolizumab) helps the immune system find and recognize cancer cells again. As a result, the immune system can attack and kill the cancer cells and stop the cancer from growing.

Drug Facts

Common BrandsKeytruda
Drug ClassPD-1 inhibitor
Controlled Substance ClassificationNot a controlled medication
Generic StatusNo lower-cost generic available
AvailabilityPrescription only

More on Keytruda (pembrolizumab) essentials

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What are the side effects of Keytruda (pembrolizumab)?

The following side effects may get better over time as your body gets used to the medication. Let your healthcare provider know immediately if you continue to experience these symptoms or if they worsen over time.

Common Side Effects

  • Higher blood sugar (52%)
  • Anemia (43%)
  • Higher liver enzyme levels (up to 33%)
  • Electrolyte changes in blood (up to 31%)
  • Lower white blood cells (30%)
  • Tiredness (25%)
  • Lower appetite (17%)
  • Trouble breathing (17%)
  • Cough (16%)
  • Rash (15%)
  • Diarrhea (12%)
  • Constipation (12%)
  • Nausea (12%)

Other Side Effects

Note: Side effects were reported by adults with non-small cell lung cancer taking Keytruda (pembrolizumab) by itself. Side effects might be different for people with a different cancer, people taking Keytruda (pembrolizumab) with other anticancer medications, and children.

Serious Side Effects

Contact your healthcare provider immediately if you experience any of the following.
  • Serious immune-related side effects: rash, diarrhea, trouble breathing, chest pain, severe stomach pain, mucus or blood in stool
  • Serious reaction during infusion: chills, fever, itching, fast heartbeat, trouble breathing

Source: DailyMed

The following side effects have also been reported

Side effects that you should report to your care team as soon as possible:

  • Allergic reactions—skin rash, itching, hives, swelling of the face, lips, tongue, or throat
  • Dry cough, shortness of breath or trouble breathing
  • Eye pain, redness, irritation, or discharge with blurry or decreased vision
  • Heart muscle inflammation—unusual weakness or fatigue, shortness of breath, chest pain, fast or irregular heartbeat, dizziness, swelling of the ankles, feet, or hands
  • Hormone gland problems—headache, sensitivity to light, unusual weakness or fatigue, dizziness, fast or irregular heartbeat, increased sensitivity to cold or heat, excessive sweating, constipation, hair loss, increased thirst or amount of urine, tremors or shaking, irritability
  • Infusion reactions—chest pain, shortness of breath or trouble breathing, feeling faint or lightheaded
  • Kidney injury (glomerulonephritis)—decrease in the amount of urine, red or dark brown urine, foamy or bubbly urine, swelling of the ankles, hands, or feet
  • Liver injury—right upper belly pain, loss of appetite, nausea, light-colored stool, dark yellow or brown urine, yellowing skin or eyes, unusual weakness or fatigue
  • Pain, tingling, or numbness in the hands or feet, muscle weakness, change in vision, confusion or trouble speaking, loss of balance or coordination, trouble walking, seizures
  • Rash, fever, and swollen lymph nodes
  • Redness, blistering, peeling, or loosening of the skin, including inside the mouth
  • Sudden or severe stomach pain, bloody diarrhea, fever, nausea, vomiting

Side effects that usually do not require medical attention (report to your care team if they continue or are bothersome):

pros-and-cons

Pros and cons of Keytruda (pembrolizumab)

thumbs-up

Pros

Recommended first-choice treatment for many types of cancers under certain situations

Less likely to cause nausea, vomiting, and hair loss (side effects that are common with traditional chemotherapy)

Given every 3 or 6 weeks, depending on the treatment plan

Uses your own immune system to attack cancer cells

thumbs-down

Cons

Given as an injection through the veins

Might cause immune-related side effects like diarrhea, rash, and lung problems

Though rare, can cause infusion reactions

Might require you to take a break from treatment and take a corticosteroid to manage side effects

pharmacist-tips

Pharmacist tips for Keytruda (pembrolizumab)

pharmacist
  • Contact your oncology care team right away if you have any immune-related side effects, like diarrhea, skin rash, or trouble breathing, at any time during your treatment with Keytruda (pembrolizumab). They could be signs that your immune system has become too active from taking the medication. You might need additional medical attention for these side effects.

    • Don’t take over-the-counter (OTC) medications to treat any side effects you have from Keytruda (pembrolizumab) without first contacting your oncology care team. OTC products that you might normally use won’t work as well to help with some side effects, like loperamide (Imodium-AD) for diarrhea. Instead, you might need to take a corticosteroid like prednisone to help manage side effects.

      • If you need to take a steroid for a few weeks to help with any side effects, don’t suddenly stop taking the steroid medication. Otherwise, you might experience uncomfortable symptoms like body aches or stomach cramps. Your care team will give you specific instructions to taper the steroid, or slowly lower the dose, to stop.

        • Make sure to get your lab tests done on time while you’re taking Keytruda (pembrolizumab). The lab results help your oncology care team check for possible side effects that don't typically cause symptoms, such as liver, kidney, or thyroid problems.

          • Though rare, you might have an infusion reaction when you’re taking Keytruda (pembrolizumab). Tell the nurse right away if you have symptoms such as chills, trouble breathing, itching, rash, or fever during your infusion. Your care team will be able to manage the reaction quickly.

            • Don’t breastfeed while you’re taking Keytruda (pembrolizumab) and for 4 months after your last dose. We don’t know whether the medication passes into human breast milk. But because of the risk to a nursing infant, it might be safer to find alternative feeding options.

              More on Keytruda (pembrolizumab) tips

              faqs

              Frequently asked questions about Keytruda (pembrolizumab)

              Is Keytruda (pembrolizumab) a type of chemotherapy?
              Keytruda (pembrolizumab) is a type of immunotherapy medication that’s called a checkpoint inhibitor. Immunotherapy is different from traditional chemotherapy. Traditional chemotherapy works by attacking any cell that grows quickly in the body, which can include cancer cells. Immunotherapy is different because it uses your own immune system to fight cancer. In particular, Keytruda (pembrolizumab) turns on your immune system so that it can find, attack, and kill the cancer cells better.
              What’s the most common side effect of Keytruda (pembrolizumab)?
              The most common side effect of Keytruda (pembrolizumab) is a group of side effects called immune-related adverse events (irAEs). They happen when the immune system becomes too active during treatment and starts to attack healthy cells in addition to cancer cells. Immune reactions can happen in any part of your body, but it most commonly affects your gut (causing diarrhea), skin (causing rash), and lungs (causing trouble breathing). It’s important to tell your care team right away if you feel or see any changes in your body that could be side effects. Some side effects might not cause symptoms, such as kidney problems. So your care team will check for those types of immune reactions with lab testing.
              Does Keytruda (pembrolizumab) cause nausea and vomiting?
              Nausea and vomiting typically aren’t common side effects of Keytruda (pembrolizumab). Keep in mind that Keytruda (pembrolizumab) is sometimes taken together with other chemotherapy medications that are known to cause nausea. Tell your oncology care team if you experience nausea while you’re taking Keytruda (pembrolizumab), whether you’re taking it by itself or with other anticancer therapies. There are several antiemetic medications that your oncologist can prescribe to help manage nausea, for example ondansetron (Zofran).
              Does Keytruda (pembrolizumab) cause hair loss?
              Hair loss isn’t typically a side effect of Keytruda (pembrolizumab). But Keytruda (pembrolizumab) is sometimes taken together with other chemotherapy medications that commonly cause hair loss. Let your oncology care team know if you notice any hair thinning or shedding while you’re taking Keytruda (pembrolizumab), whether you’re taking it by itself or with other anticancer therapies. Your care team can discuss with you about ways to lessen and manage hair loss during treatment.
              Can I keep taking Keytruda (pembrolizumab) if I have side effects from the medication?
              It depends on how severe the side effect you’re having is. Sometimes, you can keep taking Keytruda (pembrolizumab) and take supportive medications to help manage the side effect. Other times, your oncologist will pause your treatment for a few weeks and prescribe a corticosteroid (such as prednisone) to calm down your immune system and lessen side effects. Once the side effect gets better, you might be able to restart Keytruda (pembrolizumab). But if the side effect was severe, you might have to stop taking the medication altogether. Your oncologist will discuss with you whether you can continue Keytruda (pembrolizumab), take a short break from the medication, or stop the medication altogether.
              How long should I take Keytruda (pembrolizumab) for?
              It depends on several factors, such as what type of cancer you have, how well Keytruda (pembrolizumab) is working for you, and whether you’re having any bothersome or serious side effects. Sometimes, this medication is given for a specific amount of time, such as 1 or 2 years, for certain cancers. Other times, it’s given without a planned stop date, and you keep taking it as long as it’s working for you and you’re tolerating it well. Your oncologist will check how well Keytruda (pembrolizumab) is working based on lab tests, scan results, and your symptoms. The care team will also check in with you often about any side effects. Speak with your care team if you’re unsure how long you should take Keytruda (pembrolizumab).
              What foods should you avoid while taking Keytruda (pembrolizumab)?
              Avoid alcohol, caffeine, sugary beverages, greasy or fried foods, dairy, and fiber-rich foods while you’re taking Keytruda (pembrolizumab). This medication can sometimes cause diarrhea, and these foods can make diarrhea worse. If you have diarrhea during treatment, drink plenty of fluids, like soup broth or electrolyte drinks, to help prevent dehydration. Also try to eat foods that are easier on the stomach, like apples, bananas, oatmeal, and breads. Be sure to let your oncology care team know if you have diarrhea during treatment to discuss how to manage this side effect.
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              warings-icon

              What are the risks and warnings for Keytruda (pembrolizumab)?

              Keytruda (pembrolizumab) can cause some serious health issues. This risk may be even higher for certain groups. If this worries you, talk to your doctor or pharmacist about other options.

              risk-warning

              Immune-related side effects

              Side effects from immunotherapy medications such as Keytruda (pembrolizumab) are called immune-related adverse events (irAEs). These side effects happen when your immune system becomes too active and doesn’t just attack cancer cells; it attacks healthy cells, too. Immune-related side effects can happen anywhere in your body and can happen at any time during treatment. They can range from being mild to very serious.

              Some of these side events are found on your lab test results, such as liver or kidney problems. For this reason, it’s important to get your lab work done on time so your care team can monitor for these types of side effects that might not have noticeable symptoms.

              Other side effects can cause recognizable symptoms, such as diarrhea, rash, and trouble breathing. Tell your care team right away if you have these symptoms or if you notice anything unusual happening to your body. Depending on how severe your symptoms are, you might need to pause or stop taking Keytruda (pembrolizumab) and take a corticosteroid to help manage them.

              risk-warning

              Infusion-related reactions

              Rarely, people who take Keytruda (pembrolizumab) can have infusion reactions, including anaphylaxis. Your nurse will watch for these reactions during your infusion. But be sure to tell the nurse right away if you have chills, trouble breathing, flushing, itching, rash, or fever during your infusion.

              Most of the time, pausing or slowing the infusion can help manage these infusion reactions enough that you can keep taking Keytruda (pembrolizumab). But you might need to stop taking the medication altogether if the reaction is severe.

              risk-warning

              Complications from stem cell transplants

              • Risk factors: People who’ve had a stem cell (bone marrow) transplant

                Some people who’ve taken immunotherapy medications like Keytruda (pembrolizumab) and who’ve also had a stem cell transplant have experienced serious complications from the transplant. These problems can include veno-occlusive disease (VOD) and graft-versus-host disease (GVHD).

                Before you start Keytruda (pembrolizumab), let your oncology care team know if you’ve had a stem cell transplant in the past. Also tell them if you have a stem cell transplant planned at any time after you’ve completed treatment with Keytruda (pembrolizumab). Your care team will follow up with you very closely to monitor you for signs and symptoms of these complications.

                risk-warning

                Harm to unborn baby

                • Risk factors: Pregnancy

                  Keytruda (pembrolizumab) hasn’t been studied during pregnancy in humans. But based on animal studies and the way this medication works, it could cause harm to an unborn baby when it’s given during pregnancy.

                  Your oncologist might ask that you take a pregnancy test before you start Keytruda (pembrolizumab) to make sure you’re not pregnant. If you’re able to become pregnant, you should use effective birth control while you’re taking this medication and for 4 months after your last dose. Let your care team know right away if you become pregnant at any time during treatment.

                  dosage

                  Keytruda (pembrolizumab) dosage forms

                  Typical dosing for Keytruda (pembrolizumab)

                  Keytruda (pembrolizumab) is given as an intravenous (IV) infusion at a medical office or infusion center. Your dose depends on your treatment plan.

                  • Adults: The typical dose is either 200 mg given IV once every 3 weeks OR 400 mg given IV once every 6 weeks. Whether you take Keytruda (pembrolizumab) by itself or together with other anticancer therapies depends on your cancer.

                  • Children (for certain cancers only): The dose is calculated based on body weight (kg). The typical dose is 2 mg/kg (up to a maximum of 200 mg) given IV once every 3 weeks.

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                  References

                  Best studies we found

                  American Cancer Society. (n.d.). Stem cell or bone marrow transplant.

                  American Cancer Society. (2024). Infusion or immune reactions.

                  Fakhri, B., et al. (2021). Current and emerging treatment options in primary mediastinal B-cell lymphoma. Therapeutic Advances in Hematology.

                  View All References (24)

                  Fusco, M. J., et al. (2021). Tumor mutation burden and cancer treatment. Journal of the American Medical Association Oncology.

                  Ghosh, C., et al. (2021). A snapshot of the PD-1/PD-L1 pathway. Journal of Cancer.

                  Hodgens, A., et al. (2023). Corticosteroids. StatPearls.

                  InformedHealth.org. (2023). In brief: How does the immune system work? Institute for Quality and Efficiency in Health Care (IQWiG).

                  Li, K., et al. (2020). Microsatellite instability: A review of what the oncologist should know. Cancer Cell International.

                  Merck Sharp & Dohme LLC. (2024). Keytruda- pembrolizumab injection, powder, lyophilized, for solution; Keytruda- pembrolizumab injection, solution [package insert]. DailyMed.

                  National Cancer Institute. (n.d.). What is stomach cancer?

                  National Cancer Institute. (2020). Endometrial cancer treatment (PDQ®)–Patient version.

                  National Cancer Institute. (2021). Head and neck cancers.

                  National Cancer Institute. (2021). Merkel cell carcinoma treatment (PDQ®)–Patient version.

                  National Cancer Institute. (2022). Immune checkpoint inhibitors.

                  National Cancer Institute. (2023). Esophageal cancer treatment (PDQ®)–Patient version.

                  National Cancer Institute. (2023). Hodgkin lymphoma treatment (PDQ®)–Patient version.

                  National Cancer Institute. (2023). Non-small cell lung cancer treatment (PDQ®)–Patient version.

                  National Cancer Institute. (2023). What is bladder cancer?

                  National Cancer Institute. (2023). What is cervical cancer?

                  National Cancer Institute. (2024). Pembrolizumab.

                  National Cancer Institute. (2024). What is bile duct cancer (cholangiocarcinoma)?

                  National Cancer Institute. (2024). What is liver cancer?

                  National Comprehensive Cancer Network. (2024). Immunotherapy side effects: Immune checkpoint inhibitors.

                  National Comprehensive Cancer Network. (2024). Understanding immunotherapy side effects.

                  National Marrow Donor Program. (n.d.). Graft-versus-host disease basics.

                  Senzolo, M., et al. (2007). Veno occlusive disease: Update on clinical management. World Journal of Gastroenterology.

                  Zhao, P., et al. (2019). Mismatch repair deficiency/microsatellite instability-high as a predictor for anti-PD-1/PD-L1 immunotherapy efficacy. Journal of Hematology and Oncology.

                  GoodRx Health has strict sourcing policies and relies on primary sources such as medical organizations, governmental agencies, academic institutions, and peer-reviewed scientific journals. Learn more about how we ensure our content is accurate, thorough, and unbiased by reading our editorial guidelines.
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