Keytruda (Pembrolizumab) - Intravenous

What Is Keytruda?

Keytruda (pembrolizumab) is an immunotherapy infusion (given through the veins) used to treat multiple types of cancer. It belongs to a class of medication called monoclonal antibodies, which is a type of immunotherapy.

As an immunotherapy, Keytruda targets cancer cells by blocking the PD-1 pathway. PD-1 is a specific protein receptor found on cells that keeps the immune system from attacking cells in the body. While this is usually a good thing, cancer cells in the body can use the PD-1 pathway to hide from these immune attacks. By blocking PD-1, Keytruda allows the body's immune system to recognize and attack cancer cells.

If you are undergoing therapy with Keytruda, you will need to receive it intravenously (in the veins) in a healthcare setting. A healthcare provider will administer it to you.

Drug Facts

Generic Name: Pembrolizumab

Brand Name(s): Keytruda

Drug Availability: Prescription

Administration Route: Intravenous

Therapeutic Classification: Antineoplastic agent

Available Generically: No

Controlled Substance: N/A

Active Ingredient: Pembrolizumab

Dosage Form(s): Solution

What Is Keytruda Used For?

Keytruda is used to treat different types of cancer. These include:

Keytruda (Pembrolizumab) Drug Information: A person and a close up of healthy cells near cancer cells

Verywell / Dennis Madamba

How to Take Keytruda

Keytruda is given through the veins (intravenous infusion) every three to six weeks for as long as your oncologist recommends. It will usually take 30 minutes for each infusion.

The medication will be administered in a hospital or medical facility under the supervision of healthcare providers. Keep up with your appointments, and don't hesitate to discuss any concerns with the healthcare team.


Since a healthcare provider will administer Keytruda to you in a medical facility, there is no need to worry about storing the medication yourself.

How Long Will Keytruda Take to Work?

How long Keytruda takes to work will vary based on the type of cancer and stage of the disease. It can take up to a few months before a response to treatment is seen. Your oncologist will monitor your response throughout your treatment.

What Are the Side Effects of Keytruda?

Side effects from Keytruda may be due to the effects of the medication itself or the ways it can cause a reaction from the immune system.

This is not a complete list of side effects and others may occur. A healthcare provider can advise you on side effects. If you experience other effects, contact your healthcare provider. You may report side effects to the Food and Drug Administration (FDA) at or 1-800-FDA-1088.

Common Side Effects

The most common side effects from Keytruda include:

  • Fatigue
  • Muscle pain
  • Bone pain
  • Decreased appetite
  • Itching of the skin
  • Diarrhea
  • Nausea
  • Rash
  • Fever
  • Cough
  • Shortness of breath
  • Constipation
  • Abdominal pain

Side effects can occur at any time during treatment and after. Tell your cancer care team about any side effects, even mild ones. Oftentimes, side effects can be managed.

Severe Side Effects

Sometimes, the immune system may react to Keytruda by attacking healthy cells (immune-mediated reaction). This causes inflammation in this area. Some of these reactions may be severe. These may include:

  • Pneumonitis (inflammation of the lungs): Symptoms may include chest pain, cough, and shortness of breath. 
  • Colitis (inflammation of the colon): Symptoms may include diarrhea and abdominal pain.
  • Hepatitis (inflammation of the liver): No symptoms may be present, but elevation in blood liver tests may be found.
  • Endocrinopathies (inflammation of glands such as the pituitary gland, thyroid, or adrenal glands): Symptoms may include headache, vision changes, and fatigue.
  • Nephritis (inflammation of the kidneys): Symptoms may include pelvic pain, difficulty urinating, frequent urination, and blood in the urine. 
  • Skin inflammation: Symptoms may include itching or rash.

Depending on the severity of immunotherapy-related side effects, your oncologist may temporarily stop your treatment or discontinue it altogether.

Call your cancer (oncology) treatment team immediately if you experience severe side effects. Call 911 or go to the nearest emergency room if you feel your symptoms are life-threatening.

Report Side Effects

Keytruda may cause other side effects. Call your healthcare provider if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your healthcare provider may send a report to the FDA's MedWatch Adverse Event Reporting Program or by phone (800-332-1088).

Dosage: How Much Keytruda Should I Take?

A healthcare provider will administer Keytruda intravenously (in the vein) at your scheduled appointments. The dosing schedule for Keytruda is either every three or six weeks. Your oncologist will determine how long you need to undergo this treatment. Each infusion takes about 30 minutes.


It may be necessary to hold or stop altogether if severe side effects or immune reactions occur. Keytruda should also not be used while pregnant or breastfeeding.

Missed Dose

If you keep up with your regular appointments, you should not worry about missing any doses of Keytruda. Talk to your healthcare team if something comes up that might interfere with your treatment schedule.

Overdose: What Happens If I Take Too Much Keytruda?

Keytruda is only available by infusion at a hospital or cancer (oncology) treatment clinic and not taken at home. It’s unlikely that an overdose of Keytruda would occur.


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It is very important that your doctor check your progress at regular visits to make sure that this medicine is working properly. Blood and urine tests may be needed to check for unwanted effects.

Receiving this medicine while you are pregnant can harm your unborn baby. If you are a woman who can bear children, your doctor may give you a pregnancy test before you start using this medicine to make sure you are not pregnant. Use an effective form of birth control to keep from getting pregnant during treatment with this medicine and for at least 4 months after the last dose. If you think you have become pregnant while receiving the medicine, tell your doctor right away.

Tell your doctor right away if you have a cough, chest tightness, or any type of breathing problem with this medicine. These could be symptoms of a serious lung problem.

Colitis (swelling of the colon or bowel) may occur with this medicine. Tell your doctor right away if you have stomach pain or tenderness, watery or bloody diarrhea, or a fever after receiving the medicine.

Check with your doctor right away if you have pain or tenderness in the upper stomach, pale stools, dark urine, loss of appetite, nausea, unusual tiredness or weakness, or yellow eyes or skin. These could be symptoms of a serious liver problem.

Serious problems with the adrenal, pituitary, or thyroid glands (hormone glands) may occur while you are receiving this medicine. Tell your doctor if you start having continuing or unusual headaches, changes in mood or behavior (eg, being irritable or forgetful), lightheadedness, dizziness, or fainting, unusual sluggishness, or an increase in weight.

This medicine may affect blood sugar levels. If you notice a change in the results of your blood or urine sugar tests or if you have any questions, check with your doctor.

This medicine may cause serious kidney problems (eg, nephritis, kidney failure). Tell your doctor right away if you have bloody or cloudy urine, nausea, vomiting, trouble breathing, swelling of the face, feet, or lower legs, unusual tiredness or weakness, or unusual weight gain.

Tell your doctor right away if you have changes in your eyesight, severe or persistent muscle or joint pain, or severe muscle weakness after receiving this medicine.

This medicine may increase your risk for possible organ transplant rejection. Talk to your doctor about this risk.

Serious skin reactions (eg, exfoliative dermatitis, Stevens-Johnson syndrome, drug rash with eosinophilia and systemic syndrome (DRESS), and toxic epidermal necrolysis) can occur with this medicine. Check with your doctor right away if you have blistering, peeling, or loosening of the skin, chills, cough, diarrhea, itching, joint or muscle pain, red irritated eyes, red skin lesions, often with a purple center, severe acne or skin rash, sores or ulcers on the skin, mouth or lips, or swollen glands, unusual bleeding or bruising, or unusual tiredness or weakness with this medicine.

This medicine may cause infusion-related reactions. These can be life-threatening and require immediate medical attention. Tell your doctor right away if you start to have a fever, chills or shaking, dizziness, trouble breathing, itching or rash, lightheadedness or fainting after receiving this medicine.

What Are Reasons I Shouldn’t Take Keytruda?

Keytruda may not be the right treatment for you if you are pregnant, as it can harm the fetus. If you can get pregnant, use effective birth control (contraception) while undergoing treatment and for four months after your last dose.

You may also be advised not to breastfeed while taking Keytruda and for four months after the last dose, as it can affect breast milk.

What Other Medications Interact With Keytruda?

There are no known serious interactions between Keytruda and other medications.

What Medications Are Similar?

There are other immunotherapies similar to Keytruda in the way they work to treat cancer.

These include:

  • Opdivo (nivolumab)
  • Tecentriq (atezolizumab)
  • Imfinzi (durvalumab)

Like Keytruda, these drugs are also given intravenously to treat a range of cancer types.

Frequently Asked Questions

  • What is Keytruda used for?

    Keytruda is an immunotherapy infusion used for the treatment of many types of cancer.

  • How does Keytruda work?

    When someone has cancer, their immune system may not be able to recognize and fight cancer cells in the body. Keytruda works by helping the body target cancer cells to attack them.

  • What are some side effects of Keytruda?

    It may be possible not to experience side effects from Keytruda. However, the most common side effects include fatigue, muscle or bone pain, and decreased appetite. If you start to feel bad following your Keytruda dose, don't panic. Instead, talk to your healthcare team. Oftentimes, side effects are manageable.

    In some cases, Keytruda can cause severe reactions. If your side effects are severe, you may need to stop treatment temporarily or discontinue it altogether.

How Can I Stay Healthy While Taking Keytruda?

Going through cancer treatment can be overwhelming. Taking good care of your mental and physical well-being is important.

Try eating a healthy, well-balanced diet with plenty of protein and calories that includes:

  • Lots of fruits and vegetables
  • Whole grains
  • Cereals
  • Some meat and milk products

The side effects of cancer medications can sometimes make eating difficult. You may be experiencing some nausea or appetite loss. This is normal. Talk to your healthcare team about how to best manage these side effects. A registered dietitian can also help you optimize your diet for your needs.

The following are a few other general tips for staying healthy during treatment:

  • Drink plenty of water (8 to 12 cups) to stay hydrated, especially on days you feel you can't eat.
  • Get enough sleep.
  • Participate in exercise if you're feeling up to it.
  • Join a support group.

Remember that you're not alone during this time. Your healthcare team is there to guide you through your treatment plan. If you experience side effects from Keytruda, contact your cancer (oncology) treatment team immediately, especially if they are severe.

Medical Disclaimer

Verywell Health's drug information is meant for educational purposes only and is not intended to replace medical advice, diagnosis, or treatment from a healthcare provider. Consult your healthcare provider before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page.

5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. MedlinePlus. Immunotherapy for cancer.

  2. Food and Drug Administration. Keytruda label.

  3. Bajwa R, Cheema A, Khan T, et al. Adverse effects of immune checkpoint inhibitors (programmed death-1 inhibitors and cytotoxic T-lymphocyte-associated protein-4 Inhibitors): results of a retrospective study. J Clin Med Res. 2019;11(4):225-236. doi:10.14740/jocmr3750

  4. European Society of Medical Oncology. Patient guide on immunotherapy side effects.

  5. National Institute of Health's National Cancer Institute. Eating hints: before, during, and after cancer treatment.

By Julie Scott, MSN, ANP-BC, AOCNP
Julie is an Adult Nurse Practitioner with oncology certification and a healthcare freelance writer with an interest in educating patients and the healthcare community.