Immunotherapy

Immunotherapy helps your own immune system find and attack cancer, and its side effects are different from chemo.

Rosa: Hi, I'm Rosa. Immunotherapy helps your own immune system fight cancer. Let's go over how it works, and the side effects to tell your team about early.

Immunotherapy is treatment that helps your immune system fight cancer. The most common type is called checkpoint inhibitors. Drugs in this group include pembrolizumab (Keytruda), nivolumab (Opdivo), atezolizumab (Tecentriq), durvalumab (Imfinzi), and ipilimumab (Yervoy), among others.

Your immune system has built-in brakes, called checkpoints, that keep it from attacking healthy cells. Some cancers press on these brakes to hide. Checkpoint inhibitors take the brakes off, so immune cells can see and attack the cancer. It is like taking off a disguise the cancer was wearing.

Most checkpoint inhibitors are given through a vein (IV) every few weeks. Some can now be given as a shot under the skin. Treatment may continue for months or up to a couple of years, depending on the cancer and how you are doing. Immunotherapy may be given alone, with chemo, or before or after surgery.

Many people feel fairly well on immunotherapy. Common side effects include tiredness, itchy skin or rash, diarrhea, and joint aches. Because the immune system is turned up, it can sometimes attack healthy organs. This can cause inflammation of the bowel (colitis), lungs (pneumonitis), liver (hepatitis), thyroid, or other glands. Thyroid problems are common and are usually treated with a daily pill.

These immune side effects can start at any time, even months after treatment ends. Most can be treated well if they are caught early, often with steroid medicines. Tell every doctor, nurse, and emergency room that you have had immunotherapy, even years later.

Call your care team right away for diarrhea or more bowel movements than usual, belly pain, blood in your stool, new cough or shortness of breath, yellow skin or eyes, dark urine, severe tiredness, bad headaches, vision changes, dizziness, a rash that is spreading or blistering, or extreme thirst and frequent urination. If it feels very bad, call 911.

Who it helps

Immunotherapy works very well for some people and not for others. Biomarker tests on the tumor, such as PD-L1 or MSI, can help predict who may benefit. Ask if these tests were done.

Wallet card

Ask for an immunotherapy wallet card. Show it at every visit, urgent care, and emergency room so staff know to check for immune side effects.

Do not wait out diarrhea

With immunotherapy, diarrhea can be a sign of colitis. Call your team the same day instead of treating it on your own for days.

Vaccines

Flu, COVID, and pneumonia shots that are not live vaccines are usually fine and encouraged. Ask before getting any live vaccine.

Questions to ask

Is immunotherapy alone or with chemo? How long will I be on it? Which side effects should I call about right away? Will you check my thyroid and liver with blood tests?

Myth: Immunotherapy is natural, so it has no side effects

Fact: Immunotherapy is a real medicine. Most people tolerate it well, but immune side effects can be serious. Report new symptoms early.

Myth: If I have side effects, the treatment is not working

Fact: Side effects do not tell you whether the treatment is working. Scans and visits with your care team answer that question.

Last updated: 2026-10-27. Medically reviewed by Veli Bakalov, MD, medical oncologist (October 2026). General education from Step by Step, the patient portal of HemeOncBuddy.