Immunotherapy Side Effects

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Immunotherapy side effects are different from those associated with conventional cancer treatments because they derive from an overactive or misdirected immune response.  

By unleashing the power of the immune system, immunotherapy helps many patients with advanced cancer overcome their disease. Similar to nearly all types of cancer treatment, patients being treated with immunotherapy may experience side effects, also called adverse events. Since immunotherapies work differently than chemotherapy or radiation therapy, the side effects of cancer immunotherapy can differ. For example, immunotherapy does not cause hair loss, a side effect associated with chemotherapy.  

Most immunotherapies work by either enhancing pre-existing immune responses or stimulating new immune responses against cancer. Other immunotherapies, like targeted antibodies, hone in on cancer-associated markers that may also be found on healthy cells. Consequently, many of the side effects that arise during treatment with immunotherapy—referred to as immune-related adverse events—are due to overactive immune responses or immune responses directed against the wrong target (i.e., healthy tissues). These can range from mild to moderate and can become deadly under certain circumstances.

Fortunately, in most cases these side effects can be safely managed with immunosuppressive drugs as long as they are recognized and addressed early. Therefore, it is extremely important for patients to inform their care team as soon as possible if they experience any unusual sensations or developments during or after treatment with cancer immunotherapy.


Immunotherapy side effects can vary according to the type of treatment and can also be influenced by the location and type of cancer as well as a patient’s overall health. Prior to treatment, patients should consult their oncologist and care team to gain a better and fuller understanding of the potential side effects and potential risks associated with specific immunotherapies.

In general, the side effects most commonly associated with the different types of current FDA-approved immunotherapies include:

  • chills
  • constipation
  • coughing
  • decreased appetite
  • diarrhea
  • fatigue
  • fever and flu-like symptoms
  • headache
  • infusion-related reaction / injection site pain
  • nausea
  • rash
  • vomiting

Explore side effects specific to certain types of immunotherapies:


While the risk of these uncommon side effects is low, severe side effects of immunotherapy may be life-threatening and are linked to severe inflammation. They may include:

  • colitis
  • hepatitis
  • inflammation of the lung
  • kidney failure
  • neuropathy, meningitis, or encephalitis
  • severe infections
  • severe skin reactions


Side effects vary according to each therapy and how it interacts with the body. While immunotherapy’s side effects stem from the immune system, other cancer treatments have a range of side effects with a wide range of risks and severity.

Chemotherapy Side Effects

Chemotherapy targets fast-growing cancer cells, so it may damage other fast-growing normal cells in your body. Common side effects include hair loss, nausea, diarrhea, skin rash, and fatigue. Learn more about the differences between immunotherapy and chemotherapy.

Hormone Therapy Side Effects

Hormone Therapy disrupts hormone signaling in the body, either by blocking the production of hormones or preventing their activity once they’re produced. For women being treated for breast cancer, common side effects include hot flashes, vaginal dryness, changes in menstrual cycle, decreased sex drive, nausea, mood swings, and fatigue. For men being treated for prostate cancer, common side effects include hot flashes, decreased sex drive, weakened bones, diarrhea, nausea, increased size and sensitivity of breasts, and fatigue.

Radiation Therapy Side Effects

Radiation uses radioactive particles to destroy cancer cells in a localized area, so it may damage other healthy cells in that area. Side effects are often associated with the area of treatment, such as difficulty breathing when aimed at the chest, or nausea when aimed at the stomach. Skin problems and fatigue are common.

Surgery Side Effects

Surgery removes the cancerous tumor or tissue and varies according to the type of surgery performed. Common side effects include pain, fatigue, swelling, numbness, and risk of infection.


How soon and how often should I expect to experience immunotherapy side effects?

There is no set window of time during which patients might experience side effects from immunotherapy. Some immunotherapy side effects, such as infusion-related reactions or injection site pain, can occur shortly after treatment is administered. However, because immunotherapy treatments can take time to “kick in” and impact immune cell activity, some side effects may not occur until potentially weeks or months after treatment.

As with time of onset, there is no standard frequency with respect to how often immunotherapy side effects occur, although it likely depends on a particular patient’s treatment regimen (i.e., how often and how many treatments they receive). In general, the earlier side effects are reported and addressed, the better the chance that they can be effectively managed in order to lessen their frequency and duration and minimize potential pain, discomfort, or damage.

What symptoms should I look out for?

Some of the most common side effects associated with immunotherapy treatment are: chills, constipation, coughing, decreased appetite, diarrhea, fatigue, fever and flu-like symptoms, headache, infusion-related reaction or injection site pain, itching, localized rashes and/or blisters, nausea, rash, shortness of breath, vomiting, and weight loss.

If you experience any of these side effects, you should notify your healthcare team as soon as possible.

How long do immunotherapy side effects last?

The long-term side effects of immunotherapy vary from patient to patient. While the majority of immunotherapy side effects are often temporary and reversible, some of them may persist for a substantial period of time after treatment because immunotherapy can influence the activity of immune cells that remain in the body long after the drug has been cleared from the patient’s system. In rare cases, the consequences of immunotherapy side effects can be permanent.

How are immunotherapy side effects treated or managed?

Depending on the treatment, immunotherapy side effects can be treated in a number of ways. First, patients may be taken off treatment, either temporarily or permanently, in order to allow the immune activity to quiet down. Additionally, especially with checkpoint inhibitor immunotherapies, patients may receive steroids as a more active measure in order to dampen immune activity and minimize potential damage from any further autoimmune reactions.

In the case of the cytokine release syndrome (or cytokine storm), among potential CAR T cell therapy side effects, doctors may administer drugs to block the activity of certain cytokine signaling pathways, such as interluekin-1 (IL-1) or interluekin-6 (IL-6).

In general, many of immunotherapy’s potential side effects can be effectively managed, as long as they are reported and addressed in a timely manner.

Do side effects mean the immunotherapy is working?

More work still needs to be done to definitively answer this important question, although some recent studies have found that patients who experience low-grade side effects after immunotherapy were more likely to have better outcomes.

How do doctors monitor side effects?

There are a number of ways for doctors to monitor side effects; however, patients will often be aware of changes in their own bodies before their doctors have a chance to monitor and detect any side effects. As a result, it is important for patients to report any adverse changes in their health or overall well-being to their healthcare team as soon as they are aware of them.

When should I inform my doctor of side effects?

Patients should notify their doctors as soon as they can if they experience any noticeable changes in their external body appearance, their health, or their overall physiological state after being treated with immunotherapy. The earlier side effects are reported and addressed, the better the chance that they can be effectively managed in order to minimize potential pain, discomfort, or damage.

Can I speak with patients about their side effects?

Cancer patients often help inform their fellow patients about their experiences. Gain a different perspective on side effects from patients who have been treated with various immunotherapies and discover how they managed side effects.

Read Patient Immunotherapy Side Effects Experiences


Sources: U.S. Food and Drug Administration (FDA) Online Label Repository; National Cancer Institute (Hormone Therapy); National Cancer Institute (Stem Cell Transplant)

Updated August 2019

*Immunotherapy results may vary from patient to patient. Consult a healthcare professional about your treatment options.

*Immunotherapy results may vary from patient to patient.