Pronunciation: key-true-duh
Generic name: pembrolizumab
Dosage form: single-dose vial for intravenous infusion (100 mg/4 mL)
Drug class: Anti-PD-1 and PD-L1 monoclonal antibodies (immune checkpoint inhibitors)

Medically reviewed by Carmen Pope, BPharm. Last updated on Aug 19, 2025.

What is Keytruda?

Keytruda is an immunotherapy medication used to treat 18 different types of cancer, including melanoma, non-small cell lung cancer, head and neck cancer, breast cancer, and many others. Keytruda is given as an IV infusion every 3 to 6 weeks, depending on the type of cancer you have.

Keytruda is a PD-1 inhibitor that enhances the immune system's ability to fight cancer by blocking immune checkpoint proteins. Cancer cells often produce PD-L1 and PD-L2 proteins that bind to PD-1 receptors on T cells, essentially putting "brakes" on the immune response and helping tumors evade detection. Keytruda works by attaching to these PD-1 receptors first, preventing the inhibitory proteins from binding and thereby allowing T cells to mount a stronger attack against tumor cells and slow cancer growth. 

This targeted approach makes Keytruda different from traditional chemotherapy. Keytruda belongs to the drug class called immune checkpoint inhibitors and may also be called a monoclonal antibody or a biologic. 

Keytruda first gained FDA approval on September 4, 2014. There is no generic or biosimilar.

Clinical trials have shown most people respond to Keytruda within 2-4 months of starting treatment (see How long does it take for Keytruda to work?).

Latest FDA Approvals and Cancer Indications (Updated 2025)

Keytruda has received 40+ FDA approvals across 18 different cancer types. Here are the current approved uses:

Melanoma Treatment

• Unresectable or metastatic melanoma (advanced stages)
• Adjuvant melanoma treatment for Stage IIB, IIC, or III (post-surgery prevention)
• Available for adults and pediatric patients ≥12 years.

Non-Small Cell Lung Cancer (NSCLC) 

• First-line metastatic NSCLC (with chemotherapy for specific subtypes)
• PD-L1 positive NSCLC (≥1% expression as a single agent)
• Neoadjuvant NSCLC (before surgery, with chemotherapy)
• Adjuvant NSCLC (after surgery and chemotherapy)
• Post-progression NSCLC (after platinum-based therapy).

Head and Neck Squamous Cell Cancer (HNSCC)

• Resectable locally advanced HNSCC with PD-L1 CPS ≥1 (neoadjuvant/adjuvant)
• Metastatic or recurrent HNSCC (combination or single agent based on PD-L1)
• Recurrent HNSCC after platinum chemotherapy.

Breast Cancer Treatment

• Triple-negative breast cancer (TNBC) - high-risk early-stage and advanced
• Neoadjuvant TNBC (before surgery with chemotherapy)
• Metastatic TNBC with PD-L1 CPS ≥10.

Gastrointestinal Cancers

• Colorectal cancer (MSI-H or dMMR)
• Gastric cancer (HER2+ and HER2- with specific PD-L1 requirements)
• Esophageal cancer (locally advanced or metastatic)
• Hepatocellular carcinoma (liver cancer after prior therapy)
• Biliary tract cancer (with gemcitabine and cisplatin)

Blood Cancers

• Classical Hodgkin lymphoma (relapsed/refractory)
• Primary mediastinal large B-cell lymphoma

Additional Cancer Types

• Urothelial cancer (bladder cancer - multiple settings)
• Renal cell carcinoma (kidney cancer - first-line and adjuvant)
• Cervical cancer (locally advanced and metastatic)
• Endometrial carcinoma (various combinations and settings)
• Merkel cell carcinoma
• Cutaneous squamous cell carcinoma
• Malignant pleural mesothelioma

Biomarker-Based Approvals

• MSI-H or dMMR solid tumors (any cancer type with these markers)
• TMB-H cancer (≥10 mutations/Mb)

Specific PD-L1, biomarker testing, and prior treatment requirements apply. See prescribing information for detailed criteria.

Keytruda Side Effects

Most common side effects (single agent)

• Fatigue or excessive tiredness
• Pain, including pain in the stomach, muscles, bones, or joints
• Rash or itching
• Diarrhea
• Fever
• Cough
• Decreased appetite
• Shortness of breath
• Constipation
• Nausea
• Low levels of thyroid hormone.

Pediatric-specific side effects

Children may experience additional side effects:

• Higher fever rates
• Vomiting
• Headache
• Abdominal pain
• Low white blood cell counts.

Serious side effects and warnings

Keytruda can cause your immune system to attack normal organs and tissues in any area of your body and can cause serious side effects.

• These problems can sometimes become severe or life-threatening and can lead to death. You can have more than one of these problems at the same time.
• These problems may happen anytime during treatment or even after your treatment has ended

Call or see your healthcare provider right away if you develop any new or worsening signs or symptoms, including:

• Lung problems, such as cough, shortness of breath, or chest pain
• Intestinal problems, such as:
• diarrhea (loose stools) or more frequent bowel movements than usual
• stools that are black, tarry, sticky, or have blood or mucus
• severe stomach-area (abdomen) pain or tenderness.
• Liver problems such as
• yellowing of your skin or the whites of your eyes
• dark urine (tea colored)
• severe nausea or vomiting
• bleeding or bruising more easily than normal
• pain on the right side of your stomach (abdomen).
• Hormone gland problems, such as
• headaches that will not go away or unusual headaches
• urinating more often than usual
• eye sensitivity to light
• hair loss
• feeling cold
• eye problems
• rapid heartbeat
• constipation
• increased sweating
• your voice gets deeper
• extreme tiredness
• dizziness or fainting
• weight gain or weight loss
• changes in mood or behavior, such as decreased sex drive, irritability, or forgetfulness
• feeling more hungry or thirsty than usual.
• Kidney problems, such as
• a decrease in the amount of urine you produce
• swelling of your ankles
• blood in your urine
• loss of appetite.
• Skin problems, such as
• rash
• painful sores or ulcers in your mouth or your nose, throat, or genital area
• itching
• fever or flu-like symptoms
• skin blistering or peeling
• swollen lymph nodes.
• any new or worsening signs or symptoms in other organs, which may include:
• chest pain, irregular heartbeat, shortness of breath, swelling of ankles
• confusion, sleepiness, memory problems, changes in mood or behavior, stiff neck, balance problems, tingling or
• numbness of the arms or legs
• double vision, blurry vision, sensitivity to light, eye pain, changes in eyesight
• persistent or severe muscle pain or weakness, muscle cramps
• low red blood cells, and bruising.
• Infusion reactions can sometimes be severe or life-threatening. Signs and symptoms may include:
• chills or shaking
• dizziness
• itching or rash
• feeling like passing out
• flushing
• fever
• shortness of breath or wheezing
• back pain.

For people who have had an organ transplant, Keytruda may cause rejection of a transplanted organ or tissue. Your healthcare provider should tell you what signs and symptoms you should report and monitor you depending on the type of organ or tissue transplant that you have had.

Complications, including graft-versus-host-disease (GVHD), in people who have received a bone marrow (stem cell) transplant that uses donor stem cells (allogeneic). These complications can be serious and can lead to death.

• These complications may happen if you undergo transplantation either before or after being treated with Keytruda.
• Your healthcare provider will monitor you for these complications.

Get emergency medical help if you have signs of an allergic reaction to Keytruda (hives, difficulty 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).

Keytruda may cause harm to an unborn baby. Females of reproductive potential should use effective contraception.

Getting medical treatment right away for these side effects may help keep these problems from becoming more serious. 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 the FDA at 1-800-FDA-1088.

Related/similar drugs

Before taking this medicine

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

• an autoimmune disorder such as rheumatoid arthritis, Crohn's disease, ulcerative colitis, lupus, or psoriasis
• received or plan to receive a stem cell transplant that uses donor stem cells
• had an organ transplant
• had radiation to your chest
• a condition that affects your nervous system, such as myasthenia gravis or Guillain-Barré syndrome
• are pregnant or plan to become pregnant
• are breastfeeding.

Pregnancy

Keytruda may harm an unborn baby. Your healthcare provider will give you 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 healthcare provider right away if you think you may be pregnant or if you become pregnant during
treatment with Keytruda.

Breastfeeding

It is not known if Keytruda passes into breast milk. Do not breastfeed while using this medicine and for at least 4 months after your last dose.

How is Keytruda administered?

Keytruda is administered as an intravenous infusion over 30 minutes.

• In adults, a Keytruda infusion is usually given every 3 weeks or 6 weeks, depending on the cancer type being treated and your dosage.
• In children, Keytruda is usually given every 3 weeks.
• Your healthcare provider will decide how many treatments you need.
• Your healthcare provider will do blood tests to check you for side effects.
• If you miss any appointments, call your healthcare provider as soon as possible to reschedule your appointment.

You will need frequent medical tests to help your doctor determine if you are tolerating Keytruda. Do not miss any follow-up visits.

Dosing Information

Standard Keytruda Dosing Protocols

Adult Dosing Options:

• 200 mg every 3 weeks (most common)
• 400 mg every 6 weeks (alternative for convenience)

Pediatric Dosing:

• Weight-based dosing every 3 weeks
• Maximum dose same as adults

Administration Details

• Route: Intravenous infusion only
• Duration: 30-minute infusion
• Setting: Hospital or infusion center
• Monitoring: Premedications may be given to prevent reactions

Treatment Duration

• Typical duration: Up to 2 years of treatment
• Early discontinuation: May stop earlier if a complete response is achieved
• Progression: Treatment continues until disease progression or unacceptable toxicity.

What happens if I miss a dose?

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

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.

What other drugs will affect Keytruda?

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

Check for Keytruda interactions here.

Keytruda ingredients

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

Who makes Keytruda?

Keytruda is manufactured by Merck & Co. (known as MSD outside the United States and Canada), with global headquarters in Rahway, New Jersey, USA. 

Keytruda Biosimilars

Biosimilar and interchangeable products are biological products that are highly similar to and have no clinically meaningful differences from the reference product.

Reference products

These are biological products that have already been approved by the FDA, against which biosimilar products are compared. There is 1 for Keytruda.

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Further information

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

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