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Pembrolizumab (Keytruda®)

About This Drug

Pembrolizumab is used to treat cancer. It is given in the vein (IV).

Possible Side Effects

  • Nausea
  • Diarrhea (loose bowel movements)
  • Constipation (not able to move bowels)
  • Pain in your abdomen
  • Tiredness
  • Fever
  • Decreased appetite (decreased hunger)
  • Muscle and bone pain
  • Trouble breathing
  • Cough
  • Rash
  • Itching

Note: Each of the side effects above was reported in 20% or greater of patients treated with pembrolizumab. Your side effects may be different if you are receiving pembrolizumab in combination with another chemotherapy agent. Not all possible side effects are included above.

Warnings and Precautions

  • This drug works with your immune system and can cause inflammation in any of your organs and tissues and can change how they work. This may put you at risk for developing serious medical problems, which can be life-threatening.
  • Inflammation in the colon (colitis), which can be life-threatening - symptoms are loose bowel movements (diarrhea) stomach cramping, and sometimes blood in the bowel movements
  • Changes in liver function
  • Changes in kidney function
  • Inflammation (swelling) of the lungs, which can be life-threatening. You may have a dry cough or trouble breathing.
  • This drug may affect some of your hormone glands (especially the thyroid, adrenals, pituitary and pancreas).
  • Blood sugar levels may change, and you may develop diabetes. If you already have diabetes, changes may need to be made to your diabetes medication.
  • Severe allergic skin reaction, which can be life-threatening. You may develop blisters on your skin that are filled with fluid or a severe red rash all over your body that may be painful. 
  • Increased risk of organ rejection in patients who have received donor organs 
  • Increased risk of complications in patients who will undergo a stem cell transplant after receiving pembrolizumab.
  • While you are getting this drug in your vein (IV), you may have a reaction to the drug. Your nurse will check you closely for these signs: fever or shaking chills, flushing, facial swelling, feeling dizzy, headache, trouble breathing, rash, itching, chest tightness, or chest pain. These reactions may occur after your infusion. If this happens, call 911 for emergency care.

Note: Some of the side effects above are very rare. If you have concerns and/or questions, please discuss them with your medical team.

Important Information

  • This drug may be present in the saliva, tears, sweat, urine, stool, vomit, semen, and vaginal secretions. Talk to your doctor and/or your nurse about the necessary precautions to take during this time.

Treating Side Effects

  • Drink plenty of fluids (a minimum of eight glasses per day is recommended).
  • If you throw up or have loose bowel movements, you should drink more fluids so that you do not become dehydrated (lack of water in the body from losing too much fluid).
  • To help with nausea and vomiting, eat small, frequent meals instead of three large meals a day. Choose foods and drinks that are at room temperature. Ask your nurse or doctor about other helpful tips and medicine that is available to help stop or lessen these symptoms.
  • If you have diarrhea, eat low-fiber foods that are high in protein and calories and avoid foods that can irritate your digestive tracts or lead to cramping.
  • If you are not able to move your bowels, check with your doctor or nurse before you use any enemas, laxatives, or suppositories.
  • Ask your doctor or nurse about medicines that are available to help stop or lessen constipation or diarrhea.
  • To help with decreased appetite, eat small, frequent meals. Eat foods high in calories and protein, such as meat, poultry, fish, dry beans, tofu, eggs, nuts, milk, yogurt, cheese, ice cream, pudding, and nutritional supplements.
  • Consider using sauces and spices to increase taste. Daily exercise, with your doctor’s approval, may increase your appetite.
  • Manage tiredness by pacing your activities for the day. Be sure to include periods of rest between energy-draining activities.
  • Keeping your pain under control is important to your wellbeing. Please tell your doctor or nurse if you are experiencing pain.
  • If you have diabetes, keep good control of your blood sugar level. Tell your nurse or your doctor if your glucose levels are higher or lower than normal.
  • If you get a rash do not put anything on it unless your doctor or nurse says you may. Keep the area around the rash clean and dry. Ask your doctor for medicine if your rash bothers you.
  • Moisturize your skin several times a day
  • Avoid sun exposure and apply sunscreen routinely when outdoors
  • Infusion reactions may happen after your infusion. If this happens, call 911 for emergency care.

Food and Drug Interactions

  • There are no known interactions of pembrolizumab with food.
  • This drug may interact with other medicines. Tell your doctor and pharmacist about all the prescription and over-the-counter medicines and dietary supplements (vitamins, minerals, herbs and others) that you are taking at this time. Also, check with your doctor or pharmacist before starting any new prescription or over-the-counter medicines, or dietary supplements to make sure that there are no interactions.

When to Call the Doctor

Call your doctor or nurse if you have any of the following symptoms and/or any new or unusual symptoms:

  • Fever of 100.4° F (38° C) or higher
  • Chills
  • Headache that does not go away
  • Tiredness that interferes with your daily activities
  • Feeling dizzy or lightheaded
  • Wheezing or trouble breathing
  • Chest pain
  • Dry cough
  • Coughing up yellow, green or bloody mucus
  • Nausea that stops you from eating or drinking, and/or that is not relieved by prescribed medicines
  • Lasting loss of appetite or rapid weight loss of five pounds in a week
  • Diarrhea, 4 times in one day or diarrhea with lack of strength or a feeling of being dizzy
  • Blood in your stool
  • No bowel movement for 3 days or when you feel uncomfortable
  • Extreme weakness that interferes with normal activities
  • Decreased urine
  • Abnormal blood sugar
  • Unusual thirst, passing urine often, headache, sweating, shakiness, irritability
  • A new rash and/or itching
  • Rash that is not relieved by prescribed medicines
  • Pain that does not go away or is not relieved by prescribed medicines, especially in the upper right abdomen
  • Flu-like symptoms: fever, headache, muscle and joint aches, and fatigue (low energy, feeling weak) 
  • Signs of liver problems: dark urine, pale bowel movements, bad stomach pain, feeling very tired and weak, unusual itching, or yellowing of the eyes or skin
  • Signs of infusion reactions such as fever or shaking chills, flushing, facial swelling, feeling dizzy, headache, trouble breathing, rash, itching, chest tightness, or chest pain. If this happens, call 911 for emergency care.
  • If you think you are pregnant

Reproduction Concerns

  • Pregnancy warning: This drug may have harmful effects on the unborn baby. Women of childbearing potential should use effective methods of birth control during your cancer treatment and for at least 4 months after treatment. Let your doctor know right away if you think you may be pregnant.
  • Breastfeeding warning: It is not known if this drug passes into breast milk. For this reason, women should not breastfeed during treatment and for 4 months after treatment because this drug could enter the breast milk and cause harm to a breastfeeding baby. 
  • Fertility warning: Human fertility studies have not been done with this drug. Talk with your doctor or nurse if you plan to have children.

Revised August 2019

This patient information was developed by Via Oncology, LLC © 2019. This information is not intended to be used as a substitute for professional medical advice, diagnosis, or treatment. You should not rely entirely on this information for your health care needs. Ask your own doctor or health care provider any specific medical questions that you have.

CLIENT acknowledges that the Via Pathways and Via Portal are information management tools only, and that Via Oncology, LLC has not represented the Via Pathways or Via Portal as having the ability to diagnose disease, prescribe treatment, or perform any other tasks that constitute the practice of medicine. The clinical information contained in the Via Pathways and Via Portal are intended as a supplement to, and not a substitute for, the knowledge, expertise, skill, and judgment of physicians, pharmacists and other healthcare professionals involved with patient care at CLIENT facilities.