Immunotherapy Side Effects: What To Expect And How To Manage Them

If you are starting immunotherapy, it is natural to wonder about possible side effects. This treatment can be very effective for some cancers, but it can also cause unwanted symptoms because it changes how your immune system works.

The good news is that many immunotherapy side effects are manageable, especially when they are recognised early. Knowing what to look for can help you get the right support at the right time.

What Are Immunotherapy Side Effects?

Immunotherapy side effects are unwanted effects that happen when treatment activates your immune system in a way that also affects healthy tissues.

Unlike some cancer treatments that directly damage fast-growing cells, immunotherapy works by helping your immune system recognise and attack cancer. Sometimes this immune response becomes too strong or gets misdirected. When that happens, it may cause inflammation in different parts of the body.

These side effects can affect your skin, gut, lungs, liver, kidneys, hormone glands, and other organs. Some are mild, while others need urgent medical attention.

Why Immunotherapy Causes Side Effects

Immunotherapy is designed to help your immune system fight cancer cells more effectively. That is the main reason it can work well for some people.

However, an activated immune system does not always affect only cancer cells. In some cases, it also attacks normal cells by mistake. This can lead to inflammation in healthy organs and tissues.

Doctors often call these immune-related side effects or immune-related adverse events. They can happen in many different ways, which is why your care team will ask you to report even small changes in how you feel.

How Immunotherapy Side Effects Are Different From Chemotherapy

Immunotherapy side effects and chemotherapy side effects are not the same.

Here is the main difference:

• Immunotherapy side effects are usually caused by an overactive immune system attacking healthy tissues
• Chemotherapy side effects usually happen because the treatment also affects healthy fast-growing cells

This means the pattern of symptoms can be different.

With immunotherapy:

• Side effects may involve inflammation in organs such as the lungs, liver, bowel, thyroid, or skin
• Symptoms can begin during treatment or even after treatment ends
• Some side effects may need steroids or immune-suppressing medicines

With chemotherapy:

• Hair loss, mouth sores, and low blood counts are more common
• Side effects often follow a more predictable treatment cycle
• Symptoms are not usually driven by the immune system in the same way

Understanding this difference matters because cancer immunotherapy side effects may look mild at first but still need quick medical advice.

Common Immunotherapy Side Effects

Many people do not get every side effect, and some people have very few. Still, it helps to know the most common ones.

Skin-Related Side Effects

Skin changes are among the most common immunotherapy side effects.

These may include:

• Rash
• Itching
• Dry skin
• Redness
• Mild skin peeling
• Changes in skin colour, including vitiligo in some cases

Digestive Side Effects

Immunotherapy can sometimes irritate the digestive tract.

Common symptoms include:

• Diarrhoea
• Nausea
• Vomiting
• Abdominal pain or cramping
• Reduced appetite

Some people may also develop colitis, which is inflammation in the bowel.

Flu-Like And General Symptoms

Some side effects feel similar to flu or general treatment-related tiredness.

These may include:

• Fatigue
• Fever
• Chills
• Muscle aches
• Joint aches
• Weakness
• Headache

Fatigue is one of the most commonly reported cancer immunotherapy side effects.

Hormone And Gland-Related Side Effects

Immunotherapy can affect glands that control hormones, including the thyroid, pituitary, and adrenal glands.

This may lead to symptoms such as:

• Tiredness
• Weight changes
• Dizziness
• Feeling unusually cold or hot
• Mood changes
• Constipation or loose motions

These changes may develop slowly, so blood tests are often important.

Breathing-Related Symptoms

Some people may notice:

• Cough
• Shortness of breath
• Chest discomfort

These symptoms should never be ignored, especially if they are new or getting worse.

Less Common But Serious Immunotherapy Side Effects

Some immunotherapy side effects are less common but more serious. These happen when the immune system causes significant inflammation in important organs.

Examples include:

• Pneumonitis, which is inflammation in the lungs
• Hepatitis, which is inflammation in the liver
• Colitis, which can cause severe diarrhoea and abdominal pain
• Nephritis, which affects the kidneys
• Myocarditis, which affects the heart muscle
• Rare inflammation affecting the brain or nervous system

These problems can become serious quickly. That is why it is important to tell your doctor about new symptoms as soon as they start, even if they seem minor.

When Do Immunotherapy Side Effects Start?

Immunotherapy side effects do not always follow one fixed timeline.

Some Can Start Very Early

Infusion-related reactions may happen during treatment or shortly after it is given.

Many Start After Days Or Weeks

Skin changes, bowel symptoms, and fatigue may appear after treatment has begun.

Some Develop After Several Months

Hormone changes or organ inflammation can sometimes appear later in the course of treatment.

A Few Can Start After Treatment Ends

Some cancer immunotherapy side effects can happen weeks or even months after treatment has stopped.

Because timing can vary, always keep your care team informed about new symptoms.

How Long Do Immunotherapy Side Effects Last?

The duration depends on the type of side effect, how severe it is, and how quickly it is treated.

Some mild symptoms improve within days or a few weeks. Others may last longer and need ongoing treatment. Hormone-related side effects can sometimes continue for a long time and may require regular medicines even after immunotherapy stops.

This is why follow-up care is so important. Even if you feel better, your doctor may still want to monitor blood tests or symptoms for some time.

How Doctors Monitor Immunotherapy Side Effects

Your medical team will usually monitor you closely throughout treatment.

They may do this by:

• Asking about new symptoms at every visit
• Checking your skin, breathing, bowel habits, and energy levels
• Ordering blood tests to monitor liver, kidney, and thyroid function
• Checking hormone levels when needed
• Requesting scans or imaging if symptoms suggest organ inflammation
• Monitoring oxygen levels or heart-related symptoms when required
• Asking you to report changes between appointments

Your own observations matter a great deal. You are often the first person to notice when something has changed.

How Immunotherapy Side Effects Are Treated

Treatment depends on which side effect you have and how severe it is.

Early Recognition

The sooner symptoms are reported, the easier they are usually to manage.

Assessment Of Severity

Your doctor will work out whether the problem is mild, moderate, or severe.

Supportive Care For Mild Symptoms

This may include skin creams, anti-diarrhoeal treatment, fluids, rest, or dietary advice.

Medicines To Reduce Inflammation

Moderate or more serious symptoms may need treatment to calm the immune system.

Temporary Pause In Treatment

Your doctor may pause immunotherapy until the side effect improves.

Restarting Or Changing Treatment

Some people can restart treatment safely. Others may need a different plan.

Steroids And Immune-Suppressing Medications

Steroids are often used to treat moderate or severe immune-related side effects. They help calm down the immune system and reduce inflammation.

If steroids are not enough, doctors may use other immune-suppressing medicines depending on the organ involved and how severe the reaction is.

These treatments are used carefully. Your medical team balances controlling the side effect with continuing your cancer care as safely as possible.

Temporary Pause Or Stopping Immunotherapy

In some cases, your doctor may pause immunotherapy for a short time. This gives your body time to recover and allows treatment for the side effect to work.

If the side effect is severe, treatment may need to stop permanently. This decision depends on the type of reaction, how serious it is, and whether it could become dangerous if treatment continues.

Self-Care Tips To Manage Mild Immunotherapy Side Effects

For mild symptoms, self-care may help alongside your doctor’s advice.

You can often support yourself by:

• Resting when you feel tired, but trying gentle movement such as short walks
• Drinking enough fluids
• Eating simple foods if you have nausea or diarrhoea
• Using gentle moisturisers for dry or itchy skin
• Protecting your skin from strong sun exposure
• Keeping a record of symptoms, including when they start and how they change
• Taking medicines only as advised by your oncology team
• Attending all follow-up visits and blood test appointments

Do not try to manage ongoing or worsening symptoms on your own.

When To Call Your Doctor Immediately

Some symptoms need urgent medical advice.

Call your doctor or treatment team immediately if you develop:

• Shortness of breath
• New or worsening cough
• Chest pain
• Severe diarrhoea
• Blood in your stool
• Persistent vomiting
• High fever or chills
• Severe weakness or dizziness
• Yellowing of the eyes or skin
• Confusion or unusual sleepiness
• Severe abdominal pain
• Reduced urine output
• Rapidly worsening rash

Prompt action can make a major difference.

Can Immunotherapy Side Effects Be Prevented?

Not all immunotherapy side effects can be prevented. However, early education and close monitoring can reduce the risk of a mild problem becoming serious.

The best approach is to know what symptoms matter, report them early, and follow your doctor’s advice closely. Do not wait for a symptom to become severe before mentioning it.

Prevention in this setting often means early recognition rather than complete avoidance.

Living With Immunotherapy Side Effects

Living with treatment side effects can be tiring, but you do not have to manage them alone.

Many people continue treatment successfully with careful monitoring and timely symptom control. What matters most is staying in close touch with your care team, being honest about how you feel, and not dismissing new symptoms.

Even if a symptom seems small, it is worth reporting. With immunotherapy, early action is often the safest action.

Frequently Asked Questions

Do Immunotherapy Side Effects Mean The Treatment Is Working?

Not necessarily. Some people respond well to treatment and have few or no side effects. Others may develop side effects without getting the same level of benefit. Side effects alone do not show whether treatment is working.

Are Immunotherapy Side Effects Permanent?

Some are temporary and settle with treatment. Others, especially hormone-related side effects, may last longer and sometimes need ongoing management.

Can Immunotherapy Side Effects Start After Treatment Ends?

Yes. Some side effects can begin after treatment has finished. This is why follow-up care remains important even after your last cycle.

Which Immunotherapy Side Effects Are An Emergency?

Breathing difficulty, chest pain, severe diarrhoea, confusion, jaundice, severe weakness, and rapidly worsening symptoms should be treated as urgent and discussed with your doctor immediately.

Are Cancer Immunotherapy Side Effects The Same For Everyone?

No. Side effects vary from person to person. They depend on the drug used, the cancer type, your overall health, and how your immune system reacts.

The Bottom Line

Immunotherapy side effects can range from mild skin changes and fatigue to more serious inflammation in organs such as the lungs, liver, bowel, or kidneys. The most important thing is to recognise symptoms early and report them quickly.

Many side effects can be managed well when your medical team acts early. If you are receiving immunotherapy, stay alert to changes in how you feel and keep in close contact with your doctor.

Accurate monitoring can also support safer cancer care. Metropolis Healthcare can help you stay on top of important health markers with reliable diagnostic testing, expert-led reporting, and convenient access to routine investigations that may be needed during treatment monitoring.

References

1. National Cancer Institute. Immunotherapy Side Effects.
2. American Cancer Society. Immunotherapy For Cancer.
3. Cancer Research Institute. Immunotherapy Side Effects.
4. Puzanov I, Diab A, Abdallah K, et al. Managing toxicities associated with immune checkpoint inhibitors: consensus recommendations from the Society for Immunotherapy of Cancer. Journal for ImmunoTherapy of Cancer. 2017;5:95.
5. Brahmer JR, Lacchetti C, Schneider BJ, et al. Management of immune-related adverse events in patients treated with immune checkpoint inhibitor therapy. Journal of Clinical Oncology. 2018;36(17):1714-1768.