Side effects of Pembrolizumab

The side effects are mainly immune-related; therefore, the stimulation of the immune system can develop autoimmune reactions towards our body. 

Most adverse reactions that occur during treatment with pembrolizumab are reversible and managed by temporarily stopping treatment, by administering corticosteroids and/or supporting therapies.

It is very important to pay attention to the changes you observe in your body and to inform your oncologist in a timely manner to manage these reactions easily. Do not try to self-diagnose any symptoms you feel and do not take treatment before having a proper medical evaluation.

Below, we list the side effects observed with pembrolizumab so that you can recognize those symptoms for which you need to contact your oncologist.

  • Pneumonia, appearance of dyspnea (difficulty in breathing or shortness of breath), fever or cough;

  • Colitisabdominal pain, diarrhea, and even intestinal perforation;

  • Hepatitischanges in liver function;

  • Nephritischanges in renal function and increase in creatinine values;

  • Endocrinopathiesalterations of the endocrine system, including hypophysitis, diabetes mellitus, hypothyroidism or hyperthyroidism, for which attention must be paid to the eventual appearance of asthenia (tiredness), tachycardia, sweating.

Other adverse reactions

Uveitis, arthritis, myositis, pancreatitis, severe skin reactions, Guillain-Barré syndrome, myasthenic syndrome, hemolytic anemia and partial seizures in a patient with inflammatory foci in the brain parenchyma.

Based on the severity of the adverse reaction, pembrolizumab therapy should be discontinued and corticosteroids should be administered.

How Pembrolizumab is administered

Pembrolizumab is administered intravenously at a dose of 200 mg. The duration of administration is about 30 minutes and it is repeated every 21 days.

Interactions with other medicines and other forms of interaction

No formal pharmacokinetic interaction studies have been performed with pembrolizumab, but no interactions are expected. It was once believed that the use of corticosteroids (prednisone, dexamethasone, etc.) could reduce the efficacy of pembrolizumab. Recent studies have shown that corticosteroids can be used because they do not interfere with the action of pembrolizumab.


Pembrolizumab (Keytruda): the first immunotherapeutic drug for first-line treatment