Before surgery · Feeling unwell
Surgery With a Cold, Cough or Fever
You've waited weeks for your operation and now you've come down with something. Don't just turn up and hope, and don't cancel on your own either — call your team. Whether surgery goes ahead depends on how unwell you are, and that's their judgement to make with you.
The short answer
Why a cold and anesthesia don't mix
When you have a respiratory infection — even a tail-end one — your airways are irritable and carry more secretions than usual. General anesthesia adds to that, and the combination raises the chance of:
- Coughing and breath-holding as you go under or wake up.
- Laryngospasm — the voice box clamping shut — which can briefly block the airway.
- A drop in blood oxygen during the anesthetic.
- A chest infection in the days after surgery.
A fever matters too: it tells the team your body is actively fighting an infection, which is not the ideal state to undergo surgery.
What usually means postponing
- A temperature or fever.
- A productive cough (bringing up green or yellow phlegm) or a wheeze.
- Breathlessness, or a cough that's moved down into your chest.
- Feeling genuinely unwell, achy or wiped out.
A mild head cold — a runny or blocked nose, mild sore throat, no fever, feeling otherwise well — is often acceptable for minor surgery, but only your team can weigh it against your procedure and anesthetic.
Children get extra caution
The honest move: call ahead
As soon as you feel a cold or fever coming on before surgery, phone your surgical or pre-assessment team. They'll ask about your symptoms and decide whether to go ahead or reschedule — saving you a wasted, fasted trip, and keeping your anesthetic safe. Not sure whether it's worth a call? When in doubt, it's always worth a call.
Frequently asked questions
Will my surgery be cancelled if I have a cold?
Not always. A mild head cold with a runny nose and no fever often still goes ahead, especially for minor procedures — but the decision is your team's. A fever, a chesty or productive cough, wheezing, or feeling genuinely unwell makes postponement much more likely, because anesthesia is riskier then.
Why does a cold matter for anesthesia?
A recent or active respiratory infection makes the airways twitchy and full of secretions. Under anesthesia that raises the risk of coughing, breath-holding, airway spasm (laryngospasm), a drop in oxygen, and a chest infection afterwards. A fever also signals your body is actively fighting an infection.
Should I just not mention it so my surgery isn't delayed?
No. Hiding it puts you at real risk during the anesthetic. Tell your team honestly — they would far rather reschedule than have an avoidable airway or breathing problem in theatre. A short delay is much better than a serious complication.
How long do I have to wait if it's postponed?
It varies. For a simple cold, teams often wait until the symptoms have settled, commonly around two weeks. After a significant chest infection, the airways can stay sensitive for several weeks, so the wait may be longer. Your team will advise based on how you recover.