Myth: “Immunotherapy Has No Side Effects” — here's what's actually true

Mostly from the name itself. "Immunotherapy" sounds like it simply boosts your own immunity, which sounds gentle and natural — unlike chemotherapy, which most families already associate with hair loss, vomiting, and visible illness. When immunotherapy doesn't cause those familiar effects, it's easy to wrongly assume it causes none at all.

The confusion deepens because "immunotherapy" is also used loosely outside oncology — for immunity-boosting injections, wellness drips, and supplements that have nothing to do with regulated cancer treatment but borrow the same reassuring language. Families researching one often stumble onto the other, and the two get mixed up.

None of this means immunotherapy is unsafe. It means the real risks — called immune-related adverse events, or irAEs — need to be explained plainly, not assumed away because the treatment "sounds" harmless.

This table is for general understanding, not self-diagnosis. Only your oncology team can confirm whether a symptom is an irAE.

Because it delays reporting. Immune-related side effects are graded from mild to severe, and the grade — not the symptom itself — usually decides how serious the outcome becomes. A mild, grade 1 symptom reported early is often easy to manage and may not even require pausing treatment.

The same symptom, dismissed for a week or two because a patient or family believed "immunotherapy doesn't cause side effects," can progress to a severe, sometimes life-threatening reaction that needs hospital admission. This is the entire reason this myth is worth correcting firmly rather than softly: it doesn't just create confusion, it removes the urgency that catches problems while they're still manageable.

If you or a family member notices anything new during immunotherapy — a symptom that seems small, unfamiliar, or unlike a "normal" side effect — the safest assumption is that it's worth mentioning to your care team, not that it must be nothing.

1. 1

   Learn the broad categories

   Immune-related side effects can involve the skin (rash, itching), gut (diarrhoea, colitis), lungs (cough, breathlessness), liver (jaundice, raised enzymes), or hormone glands (fatigue, thyroid or adrenal problems). Knowing the categories helps you notice when something fits the pattern.

2. 2

   Track any new symptom, however mild

   A simple note of what changed and when is more useful than memory alone at your next review, and can help your team see a pattern early.

3. 3

   Report early, don't wait to see if it passes

   Most irAEs are far easier to treat at a mild grade than after they've been left to develop for a week or two.

4. 4

   Remember timing can be delayed

   Don't rule out an immune-related cause just because a symptom appears well after your last dose, or after treatment has ended.

No, and this mix-up feeds the myth directly. Cancer immunotherapy — checkpoint inhibitors prescribed by an oncologist for a specific cancer — is a regulated, monitored treatment. It is not the same as an immunity-boosting injection or wellness IV drip, which is a different category of product entirely and is not a substitute for cancer treatment.

Some Ayurvedic and homeopathic practitioners also describe their offerings as "immunotherapy" or as strengthening immunity against cancer. These are different systems of medicine, with a different evidence base for cancer specifically — the goal here is not to dismiss traditional systems, but to be clear that they are not interchangeable with checkpoint inhibitor immunotherapy. Our page on what's being offered under these labels explains the distinction in more detail. The respectful, safe approach is always the same: tell your oncology team about anything else you're taking or considering, so they can check for interactions — not hide it out of worry they'll disapprove.

• Myth: Immunotherapy Cures All Cancers — the equally common, opposite-direction myth: that immunotherapy works for every cancer and every patient.
• Is Immunotherapy the Same as an Immunity Injection or Drip? — a closer look at why these get confused, and why they're not the same thing.
• Ayurvedic and Homeopathic "Immunotherapy": What Is Being Offered — understanding these claims without dismissing traditional systems of medicine.
• Immunotherapy at CION Cancer Clinics — the full picture of how CION supports patients through immunotherapy and its side effects.

This page is for general information and does not replace a consultation. If you or someone you're supporting develops a new or worsening symptom during or after immunotherapy, contact your oncology team promptly rather than waiting to see if it passes.

Thousands of patients navigate immunotherapy safely with the right guidance

Understanding the real risks — not myths — is what keeps immunotherapy safe. Take the first step today; our team walks this part of the journey with you.