Find out more about KEYTRUDA and how to access it


What are the side effects?

Side effects may occur while taking KEYTRUDA.

KEYTRUDA works with the body’s immune system to help detect and fight certain types of cancer. KEYTRUDA can also cause the immune system to affect healthy cells in other parts of the body. These side effects can sometimes become serious.

It is important side effects are treated as early as possible.

It’s important that the Oncologist/Specialist is made aware as soon as possible if a patient notices any side effects or symptoms. Early treatment of side effects may stop them becoming more serious.

KEYTRUDA treatment may be able to continue if side effects are treated early. However, KEYTRUDA treatment may need to be stopped if side effects become more serious.

Common side effects

Any side effects should be reported to the Oncologist/Specialist or Nurse immediately by the patient. They will advise on the best management approach.

These are the most common side effects that patients may notice while taking KEYTRUDA. Common side effects may affect more than 1 in 10 people.

  • Feeling tired
  • Itching
  • Rash
  • Nausea, vomiting, diarrhoea
  • Joint pain
  • Back pain
  • Cough
  • Stomach pain
  • Headache
  • Shortness of breath
  • Hair loss
  • Upper respiratory tract infection
  • Constipation

For other side effects that affect less than 1 in 10 people speak to your Oncologist/Specialist or Nurse, or refer to the Consumer Medicine Information for KEYTRUDA. The Consumer Medicine Information (CMI) is available on request from your Oncologist/Specialist or Nurse or at http://www.medsafe.govt.nz/Consumers/cmi/k/Keytruda.pdf

Immune side effects

As KEYTRUDA works with the immune system, there are specific side effects that may result from its action on the immune system.

It is important to watch for these immune side effects so they can be treated quickly, which may allow for KEYTRUDA treatment to continue.

Patients may not have to stop KEYTRUDA treatment if the side effects are manageable. The graphic below shows where possible immune side effects can occur. The Oncologist/Specialist or Nurse will decide how to manage these side effects. KEYTRUDA treatment may be delayed or stopped if these side effects are severe.

Immuno-oncology and cancer

The immune system and cancer

Questions to ask your Doctor


KEYTRUDA (pembrolizumab) 50mg powder for infusion
KEYTRUDA is a Prescription Only Medicine Use: KEYTRUDA is used in the treatment of melanoma which cannot be removed by surgery alone or when it has spread to multiple sites in the body. In the treatment of a kind of lung cancer called non-small cell lung cancer (NSCLC). In the treatment of classical Hodgkin Lymphoma (cHL). In the treatment of urothelial carcinoma, including bladder cancer. Side effects: Immune-mediated side effects including inflammation of the lungs, colon, liver, kidneys, pituitary gland, brain, eye, muscles, nervous system, pancreas, and heart, thyroid disorders, type 1 diabetes mellitus. Severe skin reactions including Steven-Johnson syndrome and toxic epidermal necrolysis. Severe infusion reactions including hypersensitivity and anaphylaxis. Transplant recipients: rejection of a transplanted organ, graft-versus- host-disease (in people with a bone marrow transplant using donor cells). Very common side effects include diarrhea, nausea, itching, rash, joint pain, back pain, feeling tired, cough, patches of discoloured skin, stomach pain, decreased levels of sodium in blood. Tiredness, nausea, vomiting, diarrhea, constipation, shortness of breath, rash, itching, headache, hair loss, and, infections of the upper respiratory tract were reported when given in combination with chemotherapy. You may experience more than one side effect at the same time. All medicines have risks and benefits. Talk to your doctor to see if KEYTRUDA is right for you. KEYTRUDA is a funded medicine for melanoma patients– restrictions apply. KEYTRUDA is an unfunded medicine for NSCLC, cHL and urothelial carcinoma patients. Ask your health professional the cost of the medicine and any other medical fees that may apply. Use only as directed and if symptoms continue or you have side effects, see your doctor, pharmacist, or health professional. Based on data sheet prepared 16 October 2017. Marketed by: Merck Sharp & Dohme (New Zealand) Limited, Newmarket, Auckland. For additional product information, consult the Consumer Medicine Information (CMI), available on request, phone 0800 500 673 or refer to the Medsafe website www.medsafe.govt.nz.

This site is intended for New Zealand residents.

References to support this are available on request.

MSD recommends people always seek the medical advice of their healthcare professional.

Copyright © 2017 Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, New Jersey, USA. All rights reserved.

Copyright © 2017 Merck Sharp & Dohme (New Zealand) Limited. Level 3, 123 Carlton Gore Road, Newmarket, Auckland. All rights reserved.

ONCO-1208503-0027 First Issued November 2017 TAPS NA9401 essence MSD8360