Keytruda contains the active ingredient pembrolizumab, a PD-1-blocking antibody, in the form of a humanized monoclonal IgG4 kappa antibody produced in recombinant Chinese hamster ovary cells. It is an injection formulation available as a clear to slightly opalescent colorless to slightly yellow solution for intravenous use, with each vial containing 100 mg of pembrolizumab in a 4 mL solution. The formulation includes inactive ingredients such as L-histidine, polysorbate 80, sucrose, and Water for Injection.

How should I use this medication?

This medication is injected into a vein. It is given by your care team in a hospital or clinic setting. A special MedGuide will be given to you before each treatment. Be sure to read this information carefully each time. Talk to your care team about the use of this medication in children. While it may be prescribed for children as young as 6 months for selected conditions, precautions do apply.

Overdosage: If you think you have taken too much of this medicine contact a poison control center or emergency room at once. NOTE: This medicine is only for you. Do not share this medicine with others.

What if I miss a dose?

Keep appointments for follow-up doses. It is important not to miss your dose. Call your care team if you are unable to keep an appointment.

Where should I keep my medication?

This medication is given in a hospital or clinic. It will not be stored at home.

NOTE: This sheet is a summary. It may not cover all possible information. If you have questions about this medicine, talk to your doctor, pharmacist, or health care provider.

What side effects may I notice from receiving this medication?

Side effects that you should report to your care team as soon as possible: -Allergic reactions—skin rash, itching, hives, swelling of the face, lips, tongue, or throat -Dry cough, shortness of breath or trouble breathing -Eye pain, redness, irritation, or discharge with blurry or decreased vision -Heart muscle inflammation—unusual weakness or fatigue, shortness of breath, chest pain, fast or irregular heartbeat, dizziness, swelling of the ankles, feet, or hands -Hormone gland problems—headache, sensitivity to light, unusual weakness or fatigue, dizziness, fast or irregular heartbeat, increased sensitivity to cold or heat, excessive sweating, constipation, hair loss, increased thirst or amount of urine, tremors or shaking, irritability -Infusion reactions—chest pain, shortness of breath or trouble breathing, feeling faint or lightheaded -Kidney injury (glomerulonephritis)—decrease in the amount of urine, red or dark brown urine, foamy or bubbly urine, swelling of the ankles, hands, or feet -Liver injury—right upper belly pain, loss of appetite, nausea, light-colored stool, dark yellow or brown urine, yellowing skin or eyes, unusual weakness or fatigue -Pain, tingling, or numbness in the hands or feet, muscle weakness, change in vision, confusion or trouble speaking, loss of balance or coordination, trouble walking, seizures -Rash, fever, and swollen lymph nodes -Redness, blistering, peeling, or loosening of the skin, including inside the mouth -Sudden or severe stomach pain, bloody diarrhea, fever, nausea, vomiting Side effects that usually do not require medical attention (report to your care team if they continue or are bothersome): -Bone, joint, or muscle pain -Diarrhea -Fatigue -Loss of appetite -Nausea -Skin rash

This list may not describe all possible side effects. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What should I tell my care team before I take this medication?

They need to know if you have any of these conditions: -Allogeneic stem cell transplant (uses someone else's stem cells) -Autoimmune diseases, such as Crohn disease, ulcerative colitis, lupus -History of chest radiation -Nervous system problems, such as Guillain-Barre syndrome, myasthenia gravis -Organ transplant -An unusual or allergic reaction to pembrolizumab, other medications, foods, dyes, or preservatives -Pregnant or trying to get pregnant -Breast-feeding

What may interact with this medication?

Interactions have not been studied.

This list may not describe all possible interactions. Give your health care provider a list of all the medicines, herbs, non-prescription drugs, or dietary supplements you use. Also tell them if you smoke, drink alcohol, or use illegal drugs. Some items may interact with your medicine.

What should I watch for while using this medication?

Your condition will be monitored carefully while you are receiving this medication. You may need blood work while taking this medication. This medication may cause serious skin reactions. They can happen weeks to months after starting the medication. Contact your care team right away if you notice fevers or flu-like symptoms with a rash. The rash may be red or purple and then turn into blisters or peeling of the skin. You may also notice a red rash with swelling of the face, lips, or lymph nodes in your neck or under your arms. Tell your care team right away if you have any change in your eyesight. Talk to your care team if you may be pregnant. Serious birth defects can occur if you take this medication during pregnancy and for 4 months after the last dose. You will need a negative pregnancy test before starting this medication. Contraception is recommended while taking this medication and for 4 months after the last dose. Your care team can help you find the option that works for you. Do not breastfeed while taking this medication and for 4 months after the last dose.