What are side effects of immunotherapy

October 30, 2025Navis AI

For informational purposes only

This answer was generated by AI grounded in NCCN guidelines and published medical literature. It is not medical advice. Always consult your oncologist or care team before making treatment decisions.

Common Side Effects of Immunotherapy

Immunotherapy works by activating your immune system to fight cancer, which can sometimes cause your immune system to attack healthy parts of your body. These are called immune-related adverse events (irAEs).

Most Common Side Effects

According to NCCN Guidelines and the American Cancer Society, the most frequent side effects include:

Mild to Moderate (Most Common)

  • Fatigue - feeling unusually tired or weak
  • Skin reactions - rash, itching, or vitiligo (loss of skin color)
  • Diarrhea and colitis - inflammation of the intestines
  • Nausea - upset stomach
  • Loss of appetite
  • Muscle or joint aches

More Serious (Less Common but Important)

The FDA and ASCO Guidelines emphasize monitoring for these potentially serious side effects:

  • Pneumonitis - lung inflammation causing cough or breathing difficulty
  • Hepatitis - liver inflammation (elevated liver enzymes)
  • Thyroid problems - either overactive or underactive thyroid
  • Kidney inflammation (nephritis)
  • Endocrine issues - affecting pituitary, adrenal, or pancreas function
  • Neurological effects - numbness, weakness, or confusion (rare)

Important Timing Information

According to NCCN Guidelines, side effects can occur:

  • During treatment
  • Weeks to months after starting
  • Even after treatment has stopped

When to Contact Your Healthcare Team

The American Cancer Society recommends calling immediately if you experience:

  • Severe diarrhea or bloody stools
  • Difficulty breathing or persistent cough
  • Severe rash covering large areas
  • Yellowing of skin or eyes
  • Severe abdominal pain
  • Unusual weakness or confusion

Management

Most immune-related side effects are manageable, especially when caught early. Your oncology team may:

  • Temporarily pause immunotherapy
  • Prescribe corticosteroids to calm immune response
  • Provide supportive medications
  • Monitor with regular blood tests

It's crucial to report ANY new symptoms to your care team promptly - early intervention typically leads to better outcomes and allows you to continue treatment safely.

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