Staying off alcohol when taking antibiotics has been hallowed advice from GPs, pharmacists and well-meaning relatives for decades.

It’s difficult to work out exactly where the advice orginated, but Karl Kruszelnicki (Dr Karl) suggests it dates back as far back as the 1950s, when penicillin came into use as the first really effective treatment for sexually transmitted infections (STIs) such as gonorrhoea and syphilis.

Doctors were apparently worried that disinhibited acts under the influence of the demon drink could undo their expensive treatment with the new miracle drugs. So patients were advised to abstain (from alcohol) until things cleared up.

A recent survey suggests these fears may be well founded. Participants receiving treatment for STIs at a United Kingdom clinic were more likely to engage in risky sexual activity while intoxicated.

Brandice Schnabel

The advice that you shouldn’t drink alcohol while taking antibiotics does hold true for a small group of anti-infective drugs including metronidazole (Flagyl, Metronide or Metrogyl), tinidazole (Fasigyn or Simplotan) and sulfamethoxazole/trimethoprim (Bactrim, Co-trimoxazole). These drugs block one of the major pathways that metabolise alcohol and cause a rapid build up of nasties called acetaldehydes, which are responsible for many of the unpleasant physical effects of hangovers. With these drugs on board, you can be red-faced, fainting and vomiting after as little as one glass of beer.

But these anti-infective drugs have fairly specialised uses – to treat infections with organisms such as giardia (from contaminated drinking water) or intestinal worms, for instance – and it would be unusual to be prescribed these drugs without a long lecture from your doctor or pharmacist about the potential adverse reaction.

For nearly all other types of antibiotics there is no clear evidence of harm from modest alcohol intake. A comprehensive but readable summary of alcohol and medication interference can be found here.

But this doesn’t mean it’s a good idea to drink to excess when you’re in the grip of an infection, as the sedative and nauseating effects of the alcohol are likely to increase if you are unwell.

Alcohol-induced dilation of blood vessels in the limbs interferes with your body’s attempts to raise a fever to slow the spread of infection. Your kidneys will be forced by the alcohol to lose more fluid, thus increasing the risk of dehydration. And the deep, aching muscle pain produced by viral infections may be more likely to lead to serious muscle damage when combined with binge drinking.

schipulites

Some antibiotics such as isoniazid and flucloxacillin (Flopen, Staphylex) may inflame the liver (causing mild hepatitis) in a small percentage of those treated. A boozy night out could further irritate the liver, which is already working hard to get rid of the extra alcohol. A similar mild hepatitis may occur with some infections such as glandular fever, which would have the same outcome.

So if you’re unwell and thinking of having a big one at the office end-of-year party, it’s better to go easy on the alcohol whether you are on antibiotics or not. You’ll recover quicker and you’ll reduce your risk of secondary complications.

If you’re on one of the problematic drugs, it’s important to take the “no alcohol” warning seriously or you’ll quickly and deeply regret even a few mouthfuls of alcohol.

For most antibiotic users, though, a glass of bubbly or a cold beer at your office Christmas party should be fine.