Alcohol and medicines: when a drink changes how a tablet behaves

The first is a direct chemical reaction. The classic example is metronidazole, where drinking can cause a cluster of unpleasant symptoms. The second is an additive effect: alcohol and some medicines both depress the nervous system, so drowsiness and slowed breathing can be greater than either alone. The third is an effect on handling: alcohol and a medicine may compete for processing by the liver, or alcohol may change blood pressure or hydration.

Knowing which type applies to your medicine helps you judge the advice. A reaction type is usually an absolute instruction; an additive type depends on dose and tolerance; a handling type is often about moderation and timing.

Many people assume all antibiotics forbid alcohol. The NHS pages show otherwise. For metronidazole the advice is firm: avoid alcohol during treatment and for 2 days afterwards, and the NHS notes the reaction is less likely with skin cream or gel because only a small amount is absorbed. For amoxicillin the NHS says yes, you can drink alcohol while taking it.

Even where alcohol is not forbidden, being unwell, dehydrated or run down is a reason to take it easy. If you are unsure, check the page for your specific antibiotic or ask a pharmacist.

The NHS morphine page says it is best not to drink alcohol because it can make you sleepy and increase the risk of serious side effects, and the codeine page says alcohol can increase the risk of side effects. Our guide to opioids with benzodiazepines and gabapentinoids explains why depressant combinations are taken seriously.

Ibuprofen is different: the NHS says to try to avoid drinking a lot of alcohol because this can increase the risk of side effects. Heavy drinking with an anti-inflammatory increases the risk of stomach irritation, which is one reason the advice is about quantity.

For ramipril, the NHS says alcohol can lower blood pressure too much and cause dizziness, and suggests avoiding it at the start and after dose increases until you know how the medicine affects you. Standing up slowly, and not drinking before driving or operating machinery, are practical steps.

For statins the NHS simvastatin page says alcohol can increase the risk of side effects and advises not to drink too much, and the atorvastatin page indicates that limiting alcohol matters for liver-related side effects. Warfarin carries a similar caution about large amounts of alcohol.

The NHS citalopram page says it is best not to drink alcohol while taking it. Alcohol can worsen low mood and anxiety, may increase sedation with some antidepressants and can undermine the treatment you are relying on.

For lithium, the NHS says drinking alcohol is likely to make you dehydrated, which can raise lithium levels in the blood. Our lithium guide explains the wider hydration issue. If you have epilepsy or take a sedating medicine, ask your prescriber about your individual limit, since there is no single safe figure we can give.

Some people find that advice to avoid alcohol is difficult to follow. Tell your GP or pharmacist; they can help or refer you for support without judgement, and knowing your real intake lets them choose medicines more safely. Sudden stopping after heavy daily drinking can itself be dangerous, so seek advice before stopping abruptly.

Seek urgent help via 999 or A&E if someone is very drowsy, breathing slowly or cannot be woken after combining alcohol with medicines.