Immunotherapy Emergencies — Symptoms That Need Care Today

Any symptom in the table below is a reason to go to the emergency room the same hour it appears, not to schedule a call back or wait for the next infusion visit. These are the reactions that guideline bodies flag as needing same-day emergency evaluation.

This list is deliberately short — it is meant to be scanned in a moment of worry, not read start to finish. If in doubt, treat the symptom as an emergency and call for help; it is always safer to be checked and reassured than to wait.

Go to the nearest emergency room capable of treating an adult in acute distress — do not wait for a CION appointment slot, and do not drive past a closer hospital to reach a specific one. Time matters more than which hospital it is.

• Call an ambulance or go straight to the nearest emergency room — do not wait for a scheduled appointment or a callback.
• Call the CION helpline on the way so the treating oncology team is alerted and can coordinate with the emergency doctors — never let that call delay leaving the house.
• Bring a list of current medicines, any medical alert card, and the name of the treating oncology team if you can grab them quickly.
• Do not give any home remedy or "wait and see" treatment first — a red-flag symptom needs hospital-level evaluation, not home management.

Say, in the first minute, that the patient is on or has recently received cancer immunotherapy and may be having an immune-related reaction — this single sentence changes how quickly the emergency team investigates and treats.

• "They are on cancer immunotherapy and may be having an immune-related reaction" — say this before anything else.
• When the symptom started and how it has changed — sudden onset and rapid worsening both matter to the team assessing you.
• The name and contact details of the treating oncology team, so the emergency department can coordinate directly with them.
• Any other immune-related side effects the patient has had during immunotherapy — these can be relevant to how this reaction is treated.

Coordination between the emergency team and your oncology team is standard practice for these reactions — you do not need to manage that coordination yourself, only make sure both sides have the information above as early as possible.

Checkpoint immunotherapy works by releasing brakes on the immune system so it can attack cancer cells — but that same activated immune system can sometimes attack healthy organs instead, including the gut, lungs, heart, brain, hormone glands, or skin. Most of these immune-related reactions are mild and manageable, but a smaller number progress quickly and become life-threatening if not treated fast.

NCCN and ASCO guidance on immune-related adverse events treats sudden, severe reactions in these systems as top-priority emergencies precisely because early recognition changes the outcome — which is the entire purpose of this page. These reactions are a recognised, guideline-documented part of immunotherapy safety monitoring, not a rare fluke.

Once emergency treatment has stabilised the reaction, care moves into a structured follow-up pathway involving both the emergency team and your oncology team — not a return straight home.

1. 1

   Emergency stabilisation

   The emergency team treats the reaction directly, without waiting for every test result to confirm the exact cause first.

2. 2

   Confirming the reaction

   Blood tests, scans, or a specialist review confirm which organ system is affected and how severe the reaction is.

3. 3

   Oncology team informed

   Your treating oncology team is looped in as early as possible, since the reaction is linked to the immunotherapy you are receiving.

4. 4

   Specialist involved where needed

   A gastroenterologist, pulmonologist, cardiologist, neurologist, or endocrinologist may join the team depending on which system was affected.

5. 5

   Tumour board decision on immunotherapy

   Your tumour board decides whether, and when, immunotherapy can safely continue, based on how the reaction was managed and how you've recovered.

These companion pages go deeper into specific parts of the emergency picture summarised above — worth bookmarking alongside this one.

• Why an Emergency Doctor Must Know You Are on Immunotherapy — more detail on why that first sentence at the ER matters so much.
• Severe Diarrhoea: The Emergency Most Families Miss — the gut reaction that is most often mistaken for ordinary treatment side effects.
• Sudden Breathlessness on Immunotherapy — how to tell ordinary tiredness apart from a lung reaction that needs urgent care.
• Immunotherapy at CION Cancer Clinics — how we monitor and support patients through immune-related side effects, from the first infusion onward.

Immune Reactions Are Manageable When Caught Early

Patients and families who recognise symptoms early are supported by the same multidisciplinary team throughout treatment.