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Generic name: pembrolizumabPEM-broe-LIZ-ue-mab ]
Drug class: Anti-PD-1 monoclonal antibodies

Medically reviewed by Judith Stewart, BPharm. Last updated on May 17, 2023.

What is Keytruda?

Keytruda (pembrolizumab) injection belongs to a class of medications called monoclonal antibodies. Pembrolizumab works by helping your immune system to slow or stop the growth and spread of cancer cells in the body. Pembrolizumab is a type of immunotherapy that blocks the PD-1 (programmed death receptor-1) receptor which helps it stop cancer cells from hiding from the immune system.

Keytruda is used alone or in combination with other medicines to treat certain types of cancer such as:

Keytruda is often given when the cancer has spread to other parts of the body, or cannot be treated with surgery or radiation, or when other cancer treatments did not work or have stopped working.

For some types of cancer, Keytruda is given only if your tumor tests positive for "PD-L1", or if the tumor has been tested for a specific genetic marker (including "EGFR," "ALK," "HER2/neu," or "TMB").

Your doctor will review your specific type of cancer and past treatment history and other available treatments to determine if Keytruda is right for you.


Keytruda can cause serious or life-threatening side effects. Some side effects may occur during the injection. Some side effects may need to be treated with other medicine, and your cancer treatments may be delayed. You will need frequent medical tests to help your doctor determine if it is safe for you to keep receiving Keytruda.

Call your doctor at once if you have: skin problems, vision problems, fever, swollen glands, neck stiffness, chest pain, cough, shortness of breath, muscle or joint pain, pale skin, weakness, diarrhea, severe stomach pain, blood in your stools, bruising or bleeding, yellowing of the skin or eyes, a hormonal disorder, or a change in the amount or color of your urine.

Before taking this medicine

To make sure Keytruda is safe for you, tell your doctor if you have ever had:

Pembrolizumab may harm an unborn baby. You may need a pregnancy test to make sure you are not pregnant. Use effective birth control while using Keytruda and for at least 4 months after your last dose. Tell your doctor if you become pregnant.

Do not breastfeed while using this medicine, and for at least 4 months after your last dose.

How is Keytruda given?

Keytruda is given as an infusion into a vein, usually once every 3 to 6 weeks. A healthcare provider will give you this injection.

This medicine must be given slowly over 30 minutes.

You will need frequent medical tests to help your doctor determine if it is safe for you to keep receiving Keytruda. Do not miss any follow-up visits.

What happens if I miss a dose?

Call your doctor for instructions if you miss an appointment for your Keytruda injection.

What happens if I overdose?

In a medical setting an overdose would be treated quickly.

What should I avoid while receiving Keytruda?

Follow your doctor's instructions about any restrictions on food, beverages, or activity.

Keytruda side effects

Get emergency medical help if you have signs of an allergic reaction to Keytruda (hives, difficult breathing, swelling in your face or throat) or a severe skin reaction (fever, sore throat, burning eyes, skin pain, red or purple skin rash with blistering and peeling).

Seek medical treatment if you have a serious drug reaction that can affect many parts of your body. Symptoms may include skin rash, fever, swollen glands, muscle aches, severe weakness, unusual bruising, or yellowing of your skin or eyes.

Some side effects may occur during the injection. Tell your medical caregiver if you feel dizzy, nauseated, light-headed, itchy, sweaty, or have a headache, chest tightness, back pain, trouble breathing, or swelling in your face.

Keytruda causes your immune system to attack tumor cells, but it could also attack healthy organs and tissues in your body. This could lead to serious or life-threatening side effects on your lungs, liver, pancreas, kidneys, intestines, thyroid, or adrenal glands.

Keytruda may cause serious side effects. Call your doctor at once if you have:

  • new or worsening cough, chest pain, shortness of breath;

  • pale skin, easy bruising or bleeding;

  • severe muscle pain, cramps, weakness, neck stiffness;

  • double or blurry vision;

  • confusion, sleep or memory problems, changes in mood or behavior, balance problems;

  • numbness, tingling, burning pain, redness, rash, or blisters on your hands or feet;

  • fever or flu-like symptoms, swollen glands, sores in your mouth, throat, nose, or on your genital area;

  • diarrhea, severe stomach pain or tenderness, bloody or tarry stools;

  • feeling sick or uneasy, with pain or swelling near your transplanted organ;

  • high blood sugar = increased thirst, increased urination, dry mouth, fruity breath odor;

  • kidney problems = swelling, blood in your urine, urinating less, loss of appetite, feeling tired or short of breath;

  • liver problems = swelling around your midsection, right-sided upper stomach pain, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes);

  • hormonal problems = unusual headaches, sensitivity to light, eye problems, rapid heartbeats, increased sweating, extreme tiredness, weight gain or weight loss, increased hunger or thirst, increased urination, hair loss, feeling cold, constipation, hoarse or deepened voice, dizziness, fainting, decreased sex drive; or

  • low red blood cells (anemia) = pale skin, tiredness, feeling light-headed or short of breath, cold hands and feet.

Your cancer treatments may be delayed or permanently discontinued if you have certain side effects.

Common Keytruda side effects (some are more likely with combination chemotherapy) may include:

  • nausea, vomiting, stomach pain, loss of appetite, diarrhea, constipation, weight loss;

  • low blood sodium levels, abnormal thyroid, liver and kidney function tests;

  • low blood cell counts;

  • tingling or numbness in your hands or feet, loss of movement in the arms and legs;

  • bleeding;

  • pain and burning when you urinate;

  • fever, headache, feeling weak or tired, dizziness, trouble sleeping;

  • cough, hoarse voice, feeling short of breath;

  • changes in your sense of taste, dry skin and dry eyes;

  • itching, hair loss, rash or blisters on your hands or feet;

  • increased blood pressure;

  • pain in your muscles, bones, or joints; or

  • mouth sores or swelling around your mouth, nose, eyes, throat, intestines or vagina.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What other drugs will affect Keytruda?

Tell your doctor about all other cancer treatments you are receiving.

Other drugs may interact with pembrolizumab, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all other medicines you use.


Active ingredient: pembrolizumab
Inactive ingredients: L-histidine, polysorbate 80, sucrose, and water for injection


Merck Sharp & Dohme LLC, Rahway, NJ 07065, USA.

Popular FAQ

Keytruda (pembrolizumab) is a programmed death receptor-1 (PD-1)-blocking monoclonal antibody used to treat a number of different types of cancer. Keytruda is administered via a 30 min intravenous (IV) infusion every 3-6 weeks. A response to treatment is typically seen within 2-4 months of starting treatment with Keytruda, but the time it takes to work will vary based on cancer type and the stage of disease. Continue reading

In general, PD-1 immune checkpoint inhibitors like Keytruda have been shown to significantly prolong overall survival (OS) in some patients with various cancer types, but Keytruda does not always work for everyone. Continue reading

The key differences between Opdivo (nivolumab) and Keytruda (pembrolizumab) are seen in the dosing frequency, the drugs they are used in combination with and the types of cancer they have been approved for use in. Continue reading

You should only use prednisone with Keytruda if your doctor has specifically prescribed these medicines for you. Prednisone is in a class of drugs known as corticosteroids. Prednisone may be used to treat serious or life-threatening immune-mediated side effects that may occur due to Keytruda treatment. Continue reading

Keytruda is usually covered by Medicare or Medicaid, but your costs can vary depending upon your plan coverage. For example, with a Medicare Advantage plan, 41% of patients had no out-of-pocket costs for the 200 mg dose of Keytruda. Most patients with Medicaid typically pay from $4 to $8 per Keytruda infusion. Your costs may be different based on your overall income, deductible or health plan. Continue reading

Xalkori is not the same as Opdivo or Keytruda, but all three are prescription drugs are used to treat cancer. Xalkori is an oral capsule used to treat two types of cancers with genetic mutations: non-small cell lung cancer (NSCLC) and anaplastic large cell lymphoma (ALCL), a type of blood cancer. Opdivo and Keytruda are intravenous infusions both used to treat many different types of cancers, from serious types of skin cancer, to lung cancer, to blood cancers like lymphoma. Continue reading

Pembrolizumab and nivolumab are both prescription medications used to treat various types of cancers, including solid tumors and blood cancers. They may be used alone or in combination with other medicines for cancers that are more advanced, have spread in the body, or are no longer responding to previous treatments. Continue reading

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Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use Keytruda only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.