As a rule, immunotherapy causes fewer side effects than other types of cancer treatment, since it affects only the immune system, and not the entire body. Side effects that may occur depend largely on the type of cancer, the medication taken and its dose, as well as the general health of the patient at the time of treatment. 

The most common side effects:

Fatigue;
Fever;
Flu-like symptoms such as muscle or joint pain, weakness, dizziness, chills, headache, nausea, diarrhea, and runny nose.
Skin problems such as itching, swelling, redness, blisters, or mouth ulcers.
Autoimmune disorders such as myocarditis (myocardial inflammation), pneumonia, colitis (inflammation of the intestinal mucosa), endocrine (hormonal) disorders, hepatitis (inflammation of the liver), arthritis (joint pain) and uveitis (inflammation of the choroid of the eye ) Typically, these diseases occur in a mild form, but in some cases can worsen.

Traditional cancer treatment affects (including negatively) the entire human body. While immunotherapy acts selectively, exclusively on patient’s immune system. Connections between the substances PD-L1 and PD-L2 (produced by cancer cells) and PD-1 receptor (which affects the ability of human immunity to fight against tumor cells) are blocked, due to which T-lymphocytes can fight precisely against malignant tumor cells. This is how the harmful effect on the body is minimized and at the same time tumor is suppressed.

The serious effect of the action of immunotherapy is due to the fact that it removes the inhibitory effect of the tumor on the immune system and helps it to fight this disease on its own, like any other.