Before surgery · Lifestyle
Alcohol Before Surgery
A glass of wine seems harmless, but alcohol changes how you bleed, heal and respond to anesthesia. Here's when to stop — and the one situation where you must talk to your team first.
The short answer
Why alcohol and surgery don't mix
Alcohol does more under the surface than you'd think, and several of those effects work directly against a safe operation:
- More bleeding. Alcohol impairs clotting and platelet function, so you can bleed more during and after surgery.
- Anesthesia interaction. It competes with anesthetic and pain medicines in the liver, which can change how much you need and how you wake up. Regular drinkers often need more anesthetic — and may feel pain more afterwards.
- Dehydration and blood pressure. Alcohol dehydrates you and can push blood pressure up, both unhelpful around an operation.
- Slower healing and more infection. It weakens the immune system and wound healing, raising the chance of a post-op infection.
How long before surgery to stop
| When you stop | What it does for you |
|---|---|
| The day of surgery | Non-negotiable — no alcohol. Arriving with alcohol on board can get your surgery postponed. |
| 24 hours before | The minimum. Lets the immediate effects on bleeding and blood pressure settle. |
| 48–72 hours before | Better. Clotting and hydration recover further. |
| 2–4 weeks before (if you drink regularly) | Best. Measurably fewer bleeding, infection and healing complications. |
If you drink heavily or daily — read this
Be honest about how much you drink
It can feel awkward, but your honest answer is genuinely useful information, not a judgement. Knowing your real intake lets the team dose your anesthetic correctly, watch for withdrawal, and plan your pain relief. They've heard it all before — an accurate number keeps you safer than a polite one.
The night before and the morning of
Skip alcohol entirely the night before. Keep to water and clear fluids up to your fasting cut-off, get some sleep, and you'll start the day better hydrated and steadier. Not sure of your exact cut-off times? Use the fasting calculator.
Frequently asked questions
How long before surgery should I stop drinking alcohol?
Stop at least 24 hours before, and ideally 48 hours or more. If you drink regularly, cutting back for a few weeks before surgery measurably lowers your risk of bleeding, infection and slow healing — and it's worth telling your team how much you drink.
Can I have a drink the night before surgery?
It's best to avoid it. Alcohol the night before can leave you dehydrated, raise your blood pressure and interact with anesthetic drugs the next morning. Stick to water and clear fluids up to your fasting cut-off.
I drink heavily every day — should I just stop?
Don't stop abruptly on your own, and do tell your team. In people who are physically dependent, suddenly stopping can trigger dangerous withdrawal (shakes, seizures, or delirium tremens), especially during a hospital stay. Your team can plan for this and keep you safe — they need to know.
Why does alcohol matter so much for surgery?
It thins the blood and impairs clotting (more bleeding), competes with anesthetic and pain drugs in the liver, dehydrates you and raises blood pressure, and slows wound healing and immune defence — all things that make an operation riskier.