Dangerous side effects

Severe side effects can be life threatening. They may occur right away or up to 2 years after treatment ends.

If you are treated with an immune checkpoint inhibitor, it is important that you are aware of these side effects and that you call your doctor right away if they occur. If caught early, they can be treated. The list below describes dangerous side effects and their symptoms.

Side effect: Inflammation of the lung (pneumonitis)

New or worsening cough

Shortness of breath

Chest pain

Side effect: Inflammation of the liver (hepatitis)

Yellowing of skin (jaundice)

Severe nausea or vomiting

Pain on the right side of your stomach area


Tea-colored urine

Bleeding or bruising

Feeling less hungry than usual

Side effect: Inflammation of the colon (colitis)

Diarrhea (loose stools) or more bowel movements than normal

Blood in stools or black, tarry, or sticky stools

Severe abdominal pain or tenderness                   

Hormone or gland problems, especially the thyroid, pituitary, and adrenal glands and the pancreas

Headaches that will not go away

Extreme tiredness

Weight gain or weight loss

Dizziness or fainting

Changes in mood or behavior, such as decreased sex drive, irritability, or forgetfulness

Hair loss

Feeling cold


Voice getting deeper

Excessive thirst or increased urination

Side effect: Inflammation of the brain (neuropathy, meningitis, or encephalitis)



Tiredness or weakness


Memory problems


Hallucinations (seeing or hearing things that are not there)

Severe muscle weakness

Numbness or tingling in your hands or feet

Extreme sensitivity to light

Neck stiffness

Side effect: Kidney problems, including kidney failure

Change in the color or amount of urine

Blood in the urine

Swelling in the ankles

Loss of appetite

Complicated skin reactions

Rash that affects your quality of life

Blisters covering over 30% of the body


Ulcers in the mouth, nose, ears, or other mucous membranes, making it difficult to eat or drink

Side effect: Severe infections



Flu-like symptoms

Pain when urinating

Side effect: Eye problems (may indicate a more widespread problem)

Blurry vision, double vision, or other vision problems

Eye pain or redness

Side effect: Severe infusion reactions

Chills or shaking

Itching or rash


Shortness of breath or wheezing

Swelling of face or lips


Feeling like passing out

Back or neck pain