Keytruda Patient Tips

Medically reviewed by Carmen Pope, BPharm. Last updated on Aug 1, 2025.

1. How it works

• Keytruda is used to treat many different types of cancer including melanoma, non-small cell lung cancer, malignant pleural mesothelioma, head and neck squamous cell cancer, classical Hodgkin lymphoma, urothelial cancer, microsatellite instability-high or mismatch repair deficient cancer, colorectal cancer, gastric cancer, esophageal cancer, cervical cancer, hepatocellular carcinoma, biliary tract cancer, Merkel cell carcinoma, renal cell carcinoma, endometrial carcinoma, tumor mutational burden-high cancer, cutaneous squamous cell carcinoma, triple-negative breast cancer, and primary mediastinal large B-cell lymphoma. It is an immunotherapy treatment called an immune checkpoint inhibitor that helps your immune system fight cancer. Keytruda is a brand (trade) name for pembrolizumab.
• Keytruda works by blocking the PD-1 (programmed death receptor-1) pathway to help prevent cancer cells from hiding from the immune system. PD-1 receptors are found on T-cells (also called T-lymphocytes) which are a type of white blood cell. Some cancer cells avoid detection by attaching to these PD-1 receptors. This prevents the activation of the T-cell which normally would target and destroy cancer. The cancer cells can then multiply and spread. When Keytruda binds to the PD-1 receptor it prevents cancer cells from linking to and inactivating T-cells, allowing T-cell re-activation, and boosting the immune system's response against cancer. This affects the tumor but can also impact normal healthy cells.
• Keytruda belongs to the drug class called immune checkpoint inhibitors. It may also be called an anti-PD-1 monoclonal antibody.

2. Upsides

• Used to treat many different types of cancer in adults and children, such as melanoma, non-small cell lung cancer, malignant pleural mesothelioma, head and neck squamous cell cancer, classical Hodgkin lymphoma, urothelial cancer, microsatellite instability-high or mismatch repair deficient cancer, colorectal cancer, gastric cancer, esophageal cancer, cervical cancer, hepatocellular carcinoma, biliary tract cancer, Merkel cell carcinoma, renal cell carcinoma, endometrial carcinoma, tumor mutational burden-high cancer, cutaneous squamous cell carcinoma, triple-negative breast cancer, and primary mediastinal large B-cell lymphoma.
• Keytruda is an immunotherapy treatment, not chemotherapy. It does not attack cancer cells directly but instead helps the T-cells of your immune system recognize cancer.
• The dosage of Keytruda depends on the age of the patient and the type of cancer being treated but ranges from 200 mg every 3 weeks to 400 mg every 6 weeks). Keytruda is given by an intravenous infusion that takes approximately 30 minutes in an outpatient clinic or hospital.
• Keytruda may be used as a first-line treatment in some cancers or given in combination with other treatments, including chemotherapy.

3. Downsides

If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include:

• Gastrointestinal side effects (such as nausea, vomiting, stomach pain, loss of appetite, diarrhea, constipation); low sodium levels; abnormal liver function or thyroid function tests; tiredness; fever; cough; itching; hair loss; a rash, high blood pressure; soreness in the mouth, nose, throat or vagina; and muscle and joint pain are the most common side effects reported.
• Keytruda is a type of immunotherapy, and uncommonly, this can cause the immune system to attack healthy organs and tissues leading to side effects. These side effects may be serious or life-threatening and can occur anytime during or after treatment with pembrolizumab. If these symptoms occur, Keytruda may need to be stopped temporarily or permanently and other treatments, such as corticosteroids (such as prednisone) or hormone replacement therapy, initiated.
• Lung problems (pneumonitis, swelling in the lungs) may occur in about 3.4% of Keytruda patients. Symptoms include shortness of breath, chest pain, and new or worsening cough, with an average onset of 3.3 months after beginning treatment (range 2 days to 19.3 months).
• Other significant immune system-related side effects include colitis, hepatitis, hormone gland problems, kidney problems, skin reactions, mouth ulcers, confusion, and a change in eyesight.
• Regular laboratory testing and imaging studies are usually required to monitor for side effects, liver and kidney function, or disease progression. Keytruda may cause hyperglycemia, hyperlipidemia, hyponatremia, and increased AST. Anemia and lymphopenia have also been reported. Hypoalbuminemia, increased ALT, and alkaline phosphatase have also been reported.
• Keytruda may not be suitable for people with lung disease or a breathing disorder; liver disease; diabetes, or a thyroid disorder; an adrenal gland disorder; an autoimmune disorder such as lupus, Crohn's disease, or ulcerative colitis; or an organ transplant or stem cell transplant.
• Keytruda should not be given to pregnant women or those intending to become pregnant. Women who are taking Keytruda should also not breastfeed during treatment and for four months after their last dose.
• Keytruda needs to be reconstituted before administration and the reconstituted solution may be kept for up to six hours at room temperature or up to 96 hours under refrigeration. A low-protein binding 0.2-micron to 5-micron in-line or add-on filter should be used and other drugs should not be administered through the same line.

Note: In general, seniors or children, people with certain medical conditions (such as liver or kidney problems, heart disease, diabetes, seizures) or people who take other medications are more at risk of developing a wider range of side effects. View complete list of side effects

4. Bottom Line

Keytruda is an immunotherapy treatment used to treat many different cancers in adults and children such as melanoma, non-small cell lung cancer, malignant pleural mesothelioma, head and neck squamous cell cancer, some lymphomas, urothelial cancer, colorectal cancer, gastric cancer, esophageal cancer, cervical cancer, liver or biliary tract cancer, renal cell carcinoma, endometrial carcinoma, squamous cell carcinoma, or triple-negative breast cancer. Keytruda is given by intravenous infusion usually every 3 or 6 weeks. Common side effects include gastrointestinal effects, low sodium levels, abnormal liver function or thyroid function tests, tiredness, fever, cough, itching, hair loss, or a rash. In some people, Keytruda has resulted in the remission of cancer and significant tumor shrinkage.

5. Tips

• Keytruda can uncommonly cause your immune system to attack healthy organs and glands in your body. Ask your doctor or pharmacist for the Medication Guide, which lists side effects that may occur if your immune system is affected by pembrolizumab. Contact your doctor immediately if you experience any of these side effects to help keep them from becoming more serious.
• Tell your doctor immediately if you develop any severe side effects while taking Keytruda, such as shortness of breath; diarrhea; stools that are black, tarry, sticky, or contain blood or mucus; severe pain or tenderness in the stomach area; yellowing of your skin or the whites of your eyes; nausea or vomiting; dark urine; bleeding or bruising more easily than normal; rapid heartbeat; headaches; weight loss or weight gain; a skin rash; changes in eyesight; or any other side effects that you are concerned about.
• Tell your doctor about any medicines or supplements you take, including those brought from a drug store or grocery because some of these may interact with Keytruda.
• You may need to have a negative pregnancy test before starting Keytruda and use effective birth control to prevent pregnancy. Keytruda can harm a developing baby. Tell your doctor right away if you inadvertently become pregnant.
• Do not breastfeed while you are being administered Keytruda and for four months after your last dose.
• You will need frequent medical tests while you are being treated with Keytruda. Do not miss any follow-up visits.
• If you are caring for somebody who is being given Keytruda, be aware that cancer medications are powerful drugs that are broken down by the liver and kidneys of the person receiving treatment and this can take a few days. As a general rule, most cancer clinics recommend safety precautions for at least 48 hours after a dose if you are a caregiver handling body fluids (such as urine, feces, or vomit) because you could absorb these drugs through your skin if you touch the fluids. Wear rubber gloves when handling body fluids, contaminated trash, or laundry. Wash hands before and after removing gloves and wash soiled clothing and linens separately from other laundry.

6. Response and effectiveness

• Many people achieve remission with Keytruda; however, some may not. How well Keytruda works for an individual patient depends on their specific type of cancer, whether they express certain genetic markers on their tumors, their overall health at the time of treatment, previous cancer treatments, and their ability to tolerate the side effects of the medication.
• Some people have experienced significant tumor regression, tumor disappearance, or an extension of their survival time.
• Because Keytruda may be used to treat many different cancers, the response to treatment varies. Please refer to the product information or ask your doctor for specific studies relating to your particular type of cancer.
• Keytruda is usually given every three or six weeks until the person's cancer worsens or they experience intolerable or severe side effects. People who experience no disease progression with Keytruda may continue for 24 months or longer.

7. Interactions

Medicines that interact with Keytruda may either decrease its effect, affect how long it works, increase side effects, or have less of an effect when taken with Keytruda. An interaction between two medications does not always mean that you must stop taking one of the medications; however, sometimes it does. Speak to your doctor about how drug interactions should be managed.

Common medications that may interact with Keytruda include:

• corticosteroids, such as betamethasone, budesonide, cortisone, dexamethasone, hydrocortisone, or prednisone
• efgartigimod alfa
• lenalidomide or thalidomide.

Increased mortality was reported when Keytruda was added to a thalidomide analog plus dexamethasone.

Note that this list is not all-inclusive and includes only common medications that may interact with Keytruda. You should refer to the prescribing information for Keytruda for a complete list of interactions.

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Frequently asked questions

• What is the success rate of Keytruda?
• How long does it take for Keytruda to work?
• What are Monoclonal Antibodies and how do they work?
• Pembrolizumab vs. nivolumab: How do they compare?
• What is the difference between Opdivo and Keytruda?
• Can you take prednisone with Keytruda?
• How is Keytruda used for lung cancer?
• When is Keytruda used for prostate cancer?
• How effective Is Keytruda for metastatic melanoma?

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.

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