What Are the Side Effects of Immunotherapy for Cancer?

Understandably, a cancer diagnosis can be quite daunting. But in today’s era of modern medicine, new treatment options are beginning to change what it actually means to live with cancer. New cancer medications — or new uses for cancer medications — seem to be approved every month. 

Immunotherapy is one large group of cancer medications. It first popped up in the 1980s, and it’s grown to include a variety of treatments that use your immune system to fight cancer. Many people look to this type of treatment to avoid side effects that are common with chemotherapy and radiation. And although immunotherapies have a number of upsides, these unique medications are not without their own concerns.

Read on to find out more about specific side effects related to immunotherapy. 

What is immunotherapy?

Immunotherapy is a cancer treatment that uses your own immune system to fight cancer cells. There are many types of immunotherapy medications. 

In general, T cells are an important part of most immunotherapy treatments. They’re a type of white blood cell in your immune system. They help direct your immune response and attack cancer cells. 

How does immunotherapy work?

There are several different types of immunotherapy. These are discussed more below.

Immune checkpoint inhibitors

Your immune system has built-in checkpoints, or switches. They exist to make sure that your immune system is focused on fighting foreign invaders, not healthy cells. But tumor cells are sneaky. They can keep these switches “off” so they can hide from your immune system.

Immune checkpoint inhibitor medications prevent cancer cells from turning off these switches. This allows T cells to be “on” so they can find and kill cancer cells. 

Examples include ipilimumab (Yervoy), pembrolizumab (Keytruda), and nivolumab (Opdivo). 

T-cell transfer therapy

T-cell transfer therapy takes T cells from your body and they’re changed in one of two ways:

1. Your T cells can be trained to better recognize your cancer. This is known as chimeric antigen receptor (CAR) T-cell therapy. 

2. Your most efficient T cells can be selected and grown in large amounts. However, this option is currently only available in clinical trials. 

In both scenarios, modified T cells are infused back into your body as a form of treatment. 

Monoclonal antibodies

Monoclonal antibodies are proteins that are created in a lab that recognize specific targets on cancer cells. Once they find cancer cells in your body, they recruit cells from your immune system to destroy them. 

Examples include rituximab (Rituxan) and blinatumomab (Blincyto). 

Cancer vaccines

Cancer vaccines are different from vaccines used to prevent illness. Cancer vaccines help your immune system better recognize and destroy cancer cells. 

Available cancer vaccines include sipuleucel-T (Provenge) and talimogene laherparepvec (Imlygic). 

Immune system modulators

Immune system modulators are medications that stimulate or suppress your immune system to fight cancer cells. 

Many of these medications are available, but examples include lenalidomide (Revlimid), pomalidomide (Pomalyst), and imiquimod (Aldara, Zyclara).

What are the most common side effects of immunotherapy?

Many immunotherapy side effects occur due to an exaggerated reaction from your immune system. The immune system can overshoot its target and affect healthy cells and cancer cells. This results in inflammation that causes side effects. 

These side effects vary based on your medication, its dose, and the type and stage of your cancer. However, there are some side effects that all immunotherapies have in common:

• Flu-like symptoms, such as fever, chills, and body aches

• Fatigue

• Swelling

• Irregular heartbeat

• Stuffy nose

• Diarrhea

• Infection 

• Organ inflammation

Here, we'll discuss some more specific side effects based on the type of immunotherapy.

Immune checkpoint inhibitors

The most common side effects of immune checkpoint inhibitors include:

• Skin side effects, such as itching and rash

• Fatigue

• Colon inflammation

• Lung inflammation

• Liver inflammation

• Low or high thyroid function

• Muscle/joint aches

CAR T-cell therapy

The most common side effects from CAR T-cell therapy are related to a condition called cytokine release syndrome (CRS). Cytokines are proteins that help your immune system communicate. But they can also cause inflammation as part of their response. Symptoms of CRS can range from mild to severe and include:

• Fever

• Chills

• Nausea

• Rash

• Headache

Other possible side effects of CAR T-cell therapy include:

• Neurologic toxicities: This includes symptoms like dizziness, shaking, and confusion.

• Low blood counts: These include your white blood cells, red blood cells, and platelets. This can occur for weeks to months after your treatment and can raise your risk for infection.

• Low number of B cells/hypogammaglobulinemia: B cells are a type of white blood cell that make antibodies in response to a foreign invader. Low number of B cells and hypogammaglobulinemia can raise your risk for infection. Hypogammaglobulinemia means you have low levels of antibodies in your body.

Immune system modulators

Medications like lenalidomide, pomalidomide, and thalidomide can cause many side effects — several which are mentioned above. But they can also cause blood clots, nerve pain, and serious birth defects. Your care team will also recommend that you take a blood thinner, such as aspirin or warfarin, to lower risk of blood clots. 

Imiquimod is a cream, and it commonly causes skin reactions. 

Do you lose your hair with immunotherapy?

Hair loss or thinning is not a commonly reported side effect of immunotherapy. However, it’s linked to some medications. It’s rare and happens in about 1% to 2% of people receiving immune checkpoint inhibitors. It has also been reported rarely with brexucabtagene autoleucel (Tecartus) and thalidomide (Thalomid). 

What are the most serious side effects of immunotherapy?

Immunotherapy can also be associated with more severe side effects.

Immune checkpoint inhibitors

If inflammation in a certain part of your body is severe enough, you may need to stop using your medication. This risk is highest if you’re receiving two different immune checkpoint inhibitors at the same time. 

Your care team may give you corticosteroids (“steroids”) at home or in the hospital to help control inflammation.

CAR T-cell therapy

While most people experience mild-to-moderate CRS, it can be life-threatening. Damage to various organs can occur if CRS isn’t treated appropriately. Serious side effects of CRS include:

• Low blood pressure

• Low oxygen levels

• Abnormal heartbeat

• Poor kidney function

• Trouble breathing

• Capillary leak syndrome, where fluids can leak from blood vessels and cause low blood pressure and organ damage

• Macrophage activation syndrome and hemophagocytic lymphohistiocytosis, which are severe inflammatory conditions that cause widespread inflammation and organ damage

Similarly, most neurotoxicities are mild and reversible if treated appropriately. But severe reactions — such as seizures and brain swelling — can also occur.

Your care team will need to closely monitor you for at least 2 to 4 weeks after your infusion. You should also avoid driving or doing tasks that require intense concentration for at least 8 weeks.

Cancer vaccines

Imlygic is a cancer vaccine. It’s made from a weakened form of the herpes virus. It may put you at a higher risk for cold sores or eye infections. Provenge is another cancer vaccine, and it may cause side effects like blood clots, blood vessel problems, and intense infusion reactions.

Immune system modulators

Cytokines and interleukins can cause many serious side effects that are similar to CRS. 

Does immunotherapy have ‘better’ side effects than chemotherapy?

Immunotherapy works differently than chemotherapy, so expected side effects will be different. 

In many cases, people may think that immunotherapy is better tolerated than chemotherapy. For example, a recent study found that immune checkpoint inhibitors are less likely to cause severe side effects than chemotherapy. 

However, this isn’t always the case. Both chemotherapy and immunotherapy can cause severe side effects.

What can I do to manage the side effects of immunotherapy?

The most important thing you can do is tell your care team about any side effects you’re experiencing. Many of these side effects can be managed with supportive care, especially if they’re treated early. 

For example, rash and itching caused by immune checkpoint inhibitors can be treated with topical steroids and antihistamines, such as diphenhydramine (Benadryl). In other cases, medications like oral steroids or other immunosuppressants may be needed to throw ice on your immune system. 

Why trust our experts?

Written by:

Rachel Feaster, PharmD, BCOP, BCPS

Rachel Feaster has over 10 years of professional experience in ambulatory, inpatient, pharmacogenomics, and oncology care. She is board certified in oncology and pharmacotherapy.

Edited by:

Joshua Murdock, PharmD, BCBBS

Joshua Murdock, PharmD, BCBBS, is a licensed pharmacist in Arizona, Colorado, and Rhode Island. He has worked in the pharmacy industry for more than 10 years and currently serves as a pharmacy editor for GoodRx.

Reviewed by:

John Strickler, MD

John Strickler, MD, joined the Duke University faculty in 2011 and is now an associate professor of medicine in the division of medical oncology. His research focuses on precision cancer medicine: identification of genomic biomarkers that predict sensitivity or resistance to targeted therapies and immunotherapy.

Our editorial standards

Meet our experts