Pembrolizumab
Say it: pem-broh-LIZ-oo-mab · Brand names: Keytruda, Keytruda Qlex
Pembrolizumab is an immunotherapy medicine that helps your own immune system fight cancer.
What it is
Cancer cells can hide from the immune system by pressing a brake called PD-1 on immune cells. Pembrolizumab blocks this brake. This helps your immune system find and attack the cancer.
Often used for
- lung cancer
- melanoma (a skin cancer)
- head and neck cancer
- bladder and kidney cancer
- breast, cervical, and endometrial cancer
- stomach and esophagus cancer
- and some other cancers
How you get it
Pembrolizumab is usually given through a vein (IV) in a clinic over about 30 minutes. A version given as a shot under the skin also exists. It is often given once every 3 or 6 weeks. Your schedule may be different.
Common side effects and what helps
- Feeling tired. Rest and short walks can help.
- Rash or itchy skin. Use gentle soap and unscented lotion, and tell your team.
- Diarrhea. Drink plenty of fluids and tell your team, because it can be a sign of bowel inflammation.
- Muscle or joint aches. Ask your team which pain medicine is safe.
- Not feeling hungry. Eat small snacks during the day.
- Upset stomach. Eat small meals and drink fluids slowly.
Call your care team right away if you have
- Diarrhea, belly pain, or bloody or black stools
- A new or worse cough, chest pain, or shortness of breath
- Yellow skin or eyes, very dark pee, or pain on the right side of the belly
- Bad headache, extreme tiredness, dizziness, or feeling very cold or very hot
- Feeling very thirsty, peeing a lot, or confusion (signs of high blood sugar)
- Chest pain, a fast or uneven heartbeat, or muscle weakness
- A rash with blisters, peeling skin, or sores in the mouth
Before you start, tell your team
- If you have an autoimmune disease, such as Crohn's disease, ulcerative colitis, lupus, or rheumatoid arthritis
- If you have had an organ transplant or a stem cell transplant, or plan to have one
- If you have lung or breathing problems, or have had radiation to the chest
- If you have a nerve or muscle disease, such as myasthenia gravis or Guillain-Barre syndrome
- If you are pregnant, may become pregnant, or are breastfeeding
- All the medicines, vitamins, and herbal products you take, including steroids
Good to know
- It can make the immune system attack healthy organs, such as the lungs, bowel, liver, glands, kidneys, or skin. This can happen during treatment or months after it ends.
- You will have blood tests to check your liver, kidneys, thyroid, and blood sugar.
- If a side effect happens, your team may pause treatment and give you steroids. Tell every doctor you see that you are on immunotherapy.
- Some people have a reaction during the infusion, such as chills, flushing, or trouble breathing. Your nurse will watch you.
- It can harm an unborn baby. Use birth control during treatment and for a while after, as your team tells you.
Questions to ask
- How often will I get this medicine, and for how long?
- Which side effects mean I should call right away?
- Who do I call at night or on weekends?
- How will we know if it is working?
Part of these treatment plans
- Carboplatin and paclitaxel
- Carboplatin, pemetrexed and pembrolizumab
- Cisplatin with radiation
- Gemcitabine and cisplatin
Side effect guides
Sources
Quick answers
- What is Pembrolizumab?
- Pembrolizumab is an immunotherapy medicine that helps your own immune system fight cancer. Brand names: Keytruda, Keytruda Qlex.
- What is Pembrolizumab used for?
- lung cancer; melanoma (a skin cancer); head and neck cancer; bladder and kidney cancer; breast, cervical, and endometrial cancer; stomach and esophagus cancer; and some other cancers.
- How is Pembrolizumab given?
- Pembrolizumab is usually given through a vein (IV) in a clinic over about 30 minutes. A version given as a shot under the skin also exists. It is often given once every 3 or 6 weeks. Your schedule may be different.
- What are the common side effects of Pembrolizumab?
- Feeling tired. Rash or itchy skin. Diarrhea. Muscle or joint aches. Not feeling hungry. Upset stomach.
- When should I call my care team while taking Pembrolizumab?
- Diarrhea, belly pain, or bloody or black stools; A new or worse cough, chest pain, or shortness of breath; Yellow skin or eyes, very dark pee, or pain on the right side of the belly; Bad headache, extreme tiredness, dizziness, or feeling very cold or very hot; Feeling very thirsty, peeing a lot, or confusion (signs of high blood sugar); Chest pain, a fast or uneven heartbeat, or muscle weakness; A rash with blisters, peeling skin, or sores in the mouth.
- Which chemotherapy plans include Pembrolizumab?
- Carboplatin and paclitaxel, Carboplatin, pemetrexed and pembrolizumab, Cisplatin with radiation, Gemcitabine and cisplatin.
Last updated: 2026-10-27. Medically reviewed by Veli Bakalov, MD, medical oncologist (October 2026). General education from Step by Step, the patient portal of HemeOncBuddy.