SIDE EFFECTS: Tiredness, swelling ankles/feet/hands, itchy skin, or trouble sleeping may occur. If any of these effects persist or worsen, tell your doctor or pharmacist promptly. People using this medication may have serious side effects. However, your doctor has prescribed this drug because he or she has judged that the benefit to you is greater than the risk of side effects. Careful monitoring by your doctor may decrease your risk. Tell your doctor right away if you have any serious side effects, including: new/worsening cough, shortness of breath, diarrhea with blood/mucus, symptoms of liver disease (such as persistent nausea/vomiting, loss of appetite, stomach/abdominal pain, yellowing eyes/skin, dark urine), signs of kidney problems (such as change in the amount of urine, pink/bloody urine), persistent/unusual headache, dizziness/fainting, vision changes, deepening of the voice, eye redness/pain, sensitivity to light, unusual weakness, joint stiffness/pain, muscle weakness/tenderness/pain, signs of infection (such as sore throat that doesn't go away, fever, chills, burning/painful/frequent/urgent urination), easy bruising/bleeding. Pembrolizumab may cause hormone gland problems (such as thyroid, pituitary, adrenal, pancreas). Your body could make too much or too little hormone. Tell your doctor right away if you have any symptoms such as: cold or heat intolerance, unexplained weight loss/gain, mental/mood changes, slow/fast/pounding/irregular heartbeat, unusual tiredness, constipation. This medication may rarely make your blood sugar rise, which can cause or worsen diabetes. Tell your doctor right away if you have symptoms of high blood sugar such as increased thirst/urination. If you already have diabetes, check your blood sugar regularly as directed and share the results with your doctor. Your doctor may need to adjust your diabetes medication, exercise program, or diet. Get medical help right away if you have any very serious side effects, including: chest pain, seizure. A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing. This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist. In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch. In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

PRECAUTIONS: Before using pembrolizumab, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details. Before using this medication, tell your doctor or pharmacist your medical history, especially of: organ transplant. People who receive a donor stem cell transplant after treatment with pembrolizumab may have very serious (possibly fatal) complications. Ask your doctor for more details. This drug may make you dizzy. Alcohol or marijuana can make you more dizzy. Do not drive, use machinery, or do anything that needs alertness until you can do it safely. Limit alcoholic beverages. Talk to your doctor if you are using marijuana. Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products). This medication is not recommended for use during pregnancy. It may harm an unborn baby. It is important to prevent pregnancy while receiving this medication and for 4 months after treatment. Consult your doctor for more details and to discuss the use of reliable forms of birth control (such as condoms, birth control pills) while receiving this medication and for 4 months after treatment. If you become pregnant or think you may be pregnant, tell your doctor right away. It is unknown if this drug passes into breast milk. Because of the possible risk to the infant, breast-feeding while using this drug and for 4 months after stopping treatment is not recommended. Consult your doctor before breast-feeding.

DRUG INTERACTIONS: Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.

OVERDOSE: If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center.