10 Dec, 2025
Feel free to reach out to us.
10 Dec, 2025
This article is medically reviewed by Dr. Sunit Lokwani, Consultant - Medical Oncology and Clinical Hematology, HCG Cancer Centre, Indore.
Immunotherapy is an advanced treatment that involves stimulating your immune system to help your body recognize, target, and destroy cancer cells. This approach enables your immune cells to attack cancer cells more effectively by training the immune system to recognize them as harmful.
Some immunotherapy drugs involve administering additional cancer-fighting components to enhance the immune response, while others trigger the immune system to make it more active against malignant cells.
As the immune system remembers the cancer cells after immunotherapy, it is also effective against cancer recurrence. In contrast to chemotherapy drugs, which do not differentiate between malignant and healthy cells, immunotherapy precisely targets only cancer cells.
Different types of immunotherapy drugs include checkpoint inhibitors, adoptive cell therapies, and immune modulators.
Immunotherapy is usually used in advanced or refractory cases. It can be used alone or along with surgery, chemotherapy, and radiation.
Immunotherapy is also effective in autoimmune diseases, as it regulates immune activity by suppressing overactive immune responses.
Having questions like “Does immunotherapy have side effects, or what are the worst side effects of immunotherapy?” before undergoing immunotherapy is normal.
Immunotherapy does cause side effects; however, the side effects of immunotherapy are relatively less severe than those of chemotherapy. You may experience these side effects because the enhanced immunity may also attack the healthy cells.
Common immunotherapy side effects include skin rash, fatigue, cough, nausea, and fever. Various tissues in your body may exhibit inflammation or allergy-like reactions due to an increased immune response.
For instance, you may have frequent skin reactions, such as itchiness or rashes. You may also have flu-like symptoms, including fever and fatigue. Immunotherapy may also result in respiratory symptoms, such as shortness of breath.
The immunotherapy side effects are usually fairly manageable. The primary reason for these side effects is the immune system's inability to completely distinguish between malignant and healthy cells when activated by immunotherapy.
Immunotherapy is a great treatment option for patients with cancer. If you are on immunotherapy, you may experience several common side effects due to immune system activation and inflammation.
Commonly observed side effects include:
Rashes: You may report rashes, itching, redness, and irritation on the skin after initiating Immunotherapy. The side effects commonly occur at the site of injection, but can occur in the whole body or a part of it as well. The severity of side effects varies from mild to moderate. Some patients may experience severe skin reactions.
Fatigue: After immunotherapy, you may also experience fatigue. It is a common side effect in several patients. Fatigue severity ranges from mild tiredness to severe exhaustion, which may affect your routine activities.
Flu-like symptoms: After or during immunotherapy sessions, you may also have flu-like symptoms. It manifests as fever, chills, headaches, and muscle aches. It reflects increased immune system activity.
Diarrhea: Patients on immunotherapy also experience diarrhea as one of the side effects. It is because of increased immune activity; some people may also experience colon inflammation.
Nausea and vomiting: This is another side effect of Immunotherapy. Nausea and vomiting occur when the immune system attacks the gastrointestinal system, leading to inflammation.
Loss of appetite: If you are experiencing nausea, vomiting, diarrhea, and colon inflammation, you may experience a loss of appetite. Additionally, poor metabolism due to GI issues and loss of appetite may also lead to weight loss.
Shortness of breath: During immunotherapy, one may have shortness of breath, along with other accompanying symptoms, including cough and lung inflammation. In some cases, the shortness of breath or lung inflammation can become severe, requiring prompt medical intervention.
Hypothyroidism: Immunotherapy also affects your hormone-producing glands. This results in various endocrine disruptions, such as hypothyroidism or adrenal insufficiency.
Other immunotherapy side effects: Less common immunotherapy side effects include low blood pressure during treatment and infusion-related reactions. Rarely, immunotherapy may also affect your heart, liver, or nervous system.
Immune checkpoint inhibitors, due to their strong immune activation, can cause a broader range of immune-related adverse effects.
These side effects can be effectively managed with adequate medical support or by having your doctor adjust the treatment. You will be closely monitored by your care team in order to prevent serious complications.
You should be aware of the different side effects of Immunotherapy that you may possibly experience during and after the treatment. This will help you prepare better.
Experiencing side effects from immunotherapy does not necessarily indicate the treatment's efficacy.
The immune-related side effects indicate that immunotherapy has activated the immune system. However, it is not a direct indicator of treatment success.
The duration of side effects also varies widely among patients. You may experience mild symptoms, such as a rash or fatigue, that may last for a few days to a few weeks. More severe immune-related effects may continue for several months.
Immunotherapy works by triggering the immune system to detect and attack cancer cells efficiently. However, it may cause inflammation that affects multiple organs and body systems. It is because immunotherapy drugs target healthy tissues.
Skin: One of the most commonly affected organs with immunotherapy is your skin. You may experience various skin issues, such as itching, rashes, and dryness.
Skin is most commonly affected because of its highly immunoreactive characteristic.
Liver: You may also have immune-mediated hepatitis. Inflammation results in elevated liver enzymes and liver damage.
You may experience jaundice, fatigue, and abdominal discomfort. Early detection is important to prevent severe liver damage.
Lung: If you are undergoing immunotherapy, you are always at an increased risk for developing pneumonitis.
It causes lung inflammation, leading to shortness of breath, cough, and chest pain. The condition ranges from mild to life-threatening, needing rapid diagnosis and steroidal treatment to lower immune activation in lung tissues.
Endocrine system: Immunotherapy also affects your endocrine system. Your thyroid gland is frequently affected and may lead to hypothyroidism or hyperthyroidism. You may experience weight changes, fatigue, temperature sensitivity, and mood shifts.
Inflammation may also occur in the other endocrine glands, such as the pituitary gland or adrenal gland. You may have disrupted hormonal balance and may require hormone replacement therapy.
Gastrointestinal tract: Immunotherapy also affects the organs of the gastrointestinal tract. You may have colon inflammation that may lead to abdominal pain, diarrhea, and bleeding.
Inflammation of the gastrointestinal tract is caused by immune cells attacking the intestinal mucosal lining. You should consult a doctor in case you have blood in your stools or abdominal pain to avoid severe complications.
There are several approaches that specialists use to manage immunotherapy side effects. These include early detection, careful monitoring, and appropriate medical interventions. This treatment reduces inflammation and prevents complications.
You should be under constant monitoring, including frequent clinical evaluation and laboratory tests, to detect signs of organ inflammation. These signs are thyroid hormone imbalance, liver enzyme elevations, and changes in lung function. One should immediately report the symptoms, such as diarrhea, rash, fatigue, cough, and shortness of breath, to their healthcare provider.
If you have mild side effects, the doctor may provide you with supportive care, such as antihistamines and antidiarrheal medications. For moderate to severe immune-related side effects, you may be prescribed corticosteroids, such as prednisone. Steroids can suppress immune system activity, thereby reducing inflammation.
In some cases, immunotherapy should be temporarily paused or permanently discontinued due to severe side effects.
You should contact the doctor immediately if you experience severe side effects from immunotherapy or if the symptoms are worsening.
Common immunotherapy side effects that are alarming include abdominal pain or severe diarrhea suggestive of colitis, new or worsening cough, and difficulty breathing suggestive of pneumonitis. You may also contact the doctor if you have changes in vision, severe headache, confusion, or muscle weakness.
Other symptoms to be monitored and reported to the doctor are persistent vomiting, high fever, sudden swelling, and severe rash. Early communication with your doctor is crucial for timely interventions to manage these side effects and prevent further complications.
In case you have not received an immediate response from the doctor and the symptoms are worsening, it is better to seek emergency care. Monitoring of side effects enables rapid intervention.
The best way to stay safe during immunotherapy is to actively take part in routine monitoring. You should immediately report the new or worsening symptoms to your doctor. Adopt healthy habits. You should consult the doctor for regular checkups, including blood tests and imaging. It will help detect side effects early, before they become severe.
Apart from the drugs used to manage the common immunotherapy side effects, such as steroids and antihistamines, you should also maintain good nutrition, stay hydrated, avoid infections through vaccination and hand hygiene, manage stress, and get sufficient sleep.
Immunotherapy is an advanced treatment option, particularly in patients not responding to conventional treatment. Unlike chemotherapy, which does not differentiate between cancer cells and healthy cells, immunotherapy targets malignant cells precisely. However, immunotherapy also causes certain side effects.
Immunotherapy side effects include various vital organs, such as the liver, lungs, and gastrointestinal tract. The most commonly affected organ is the skin. Patients experience itching, redness, and dryness.
Some other common immunotherapy side effects include colitis, diarrhea, high fever, joint pain, pneumonitis, hepatitis, and hormonal imbalance. If you are on immunotherapy and have new or worsening side effects, contact your doctor for appropriate interventions to manage them.
Dr. Sunit Lokwani
Consultant - Medical Oncology And Clinical Haematology
MBBS, MD (General Medicine), DM (Medical Oncology)
Dr. Sunit Lokwani is an accomplished consultant in hematology and medical oncology, specializing in the treatment and management of various types of cancer through systemic treatment approaches. He is available for consultations at HCG Cancer Centre, a leading cancer hospital in Indore. His credentials include an MBBS degree, an MD (General Medicine) degree, and a DM (Medical Oncology). Additionally, he is a certified intensivist from the Indian Society of Critical Care Medicine (ISCCM) and the Chinese University of Hong Kong (CUHK), as well as a DM-certified specialist by the IDF.
Appointment Link: Book an Appointment with Dr. Sunit Lokwani.
