Dangers of Mixing Codeine and Alcohol

Codeine is a common painkiller, and alcohol is a part of many people’s lives in Britain. But taking codeine and alcohol together can be very dangerous. In 2024, codeine and alcohol were both involved in 56 drug-poisoning deaths in England and Wales, 36 men and 20 women. Those figures only count codeine that is not part of a combination painkiller. As this is how codeine is often taken in Britain, the true number is almost certainly higher. The first step to avoiding that overdose risk is to understand where it comes from.

Why mixing codeine and alcohol is so dangerous

Both codeine and alcohol are depressants, which means they slow the systems that keep you alive. These include your breathing and your level of consciousness.

The two substances do this by different means. Alcohol acts mainly on a calming chemical messenger called GABA, while codeine works on the opioid system. The result is a slowing down that arrives from two directions at once.

This is what makes the combination so dangerous. When two depressants are in the body together, each amplifies the effect of the other. This means that a quantity of either codeine or alcohol that you could usually tolerate alone can do real harm.

More than half of all drug-poisoning deaths in England and Wales involve more than one substance, and the mixing of depressants and alcohol is behind many of them.

What central nervous system depression means

The central nervous system is the brain and spinal cord. This is the control centre for nearly everything your body does without being told. Depressants like codeine and alcohol slow the messages running through that centre. In small, careful amounts, the effect is what relieves pain or helps a person relax. When there is too much for your system to handle, it begins to switch off vital functions.

Breathing is the most important of these functions. The drive to breathe is automatic, governed by a part of the brainstem that keeps you taking breaths even while you’re asleep. Opioids and alcohol weaken that drive, so your breath becomes slower and more shallow. If it slows far enough, the body stops taking in the oxygen it needs, and that is how this combination kills.

How codeine turns into morphine inside you

There is a further twist that makes codeine in particular hard to predict. Codeine is what is called a prodrug, meaning it does relatively little on its own. The liver has to convert it into morphine, which is what produces the real opioid effect. An enzyme called CYP2D6 does that job, and the codeine metabolism relies on it to work.

People carry quite different versions of that enzyme, so morphine conversion can vary a lot. Some are slow converters who get little effect from codeine at all. Others are ultra-rapid converters, who turn codeine into morphine quickly and in larger amounts. This second group is potentially at a higher overdose risk from what looks like an ordinary dose.

Most people have no idea which group they’re in. You can’t feel your own enzyme rate, so you can’t know in advance how strong a given amount of codeine will be for you. But the danger is taken seriously at the highest level. Codeine medicine labels carry a prominent warning that ultra-rapid converters can suffer life-threatening breathing problems from standard doses.

Why alcohol makes codeine even less predictable

This is also the group that should be most careful about mixing alcohol and codeine. The opioid and alcohol interaction does not just stack one known effect on another because the codeine effects were never fixed to begin with. A person who happens to be a fast converter and has a drink or two on top of their codeine is combining an unusually large dose of morphine with a second depressant. This is often done with no sense of the quantity of depressants they are really asking their system to cope with.

The hidden opioid in the cabinet

A particular danger in the UK is co-codamol, a common painkiller that combines codeine with paracetamol and can be bought over the counter in lower strengths. It is meant only for short spells, and the version sold in pharmacies should not be used for more than three days without advice. Many people take it without quite registering that they are taking an opioid at all, and may pour a glass of wine alongside it without a second thought.

The drug interaction dangers are exactly the same as with codeine on its own, with one addition. Paracetamol is hard on the liver, and alcohol strains the liver too, so a regular habit of mixing the two carries its own quieter harm on top of the immediate risk. It was explained in the intro that the official figures on deaths due to the mixing of codeine and alcohol do not include combination medicines. This means that the number of deaths, including co-codamol, is not fully known.

Knowing the warning signs

If you’re ever with someone who has taken codeine and alcohol together, certain signs mean their breathing is in danger, and they need an ambulance straight away.

Their pupils may shrink to pinpoints, their breathing may turn slow, shallow or irregular, and snoring or gurgling sounds are a sign that their airway is blocked. This is often mistaken for someone sleeping deeply, but it is a major warning sign.

They may be impossible to rouse, their skin may turn pale or bluish, and on brown or black skin, this shows most clearly on the lips, gums and nailbeds.

If you see any of these signs, call 999, tell the operator what has been taken, and stay until help arrives. Turning them onto their side while help is on its way can stop them choking if they are sick. If you have it, you can administer naloxone, which is a drug that reverses an opioid overdose temporarily. This is always worth doing, even if you only slightly suspect they have used opioids, because naloxone won’t harm them if they haven’t.

Even a small amount is a gamble

It’s tempting to think a single drink with a couple of tablets is harmless, and most of the time, a person will get away with it. The trouble is that you can’t tell in advance which time will be different. You have no way of knowing how much morphine your body has made, and the depressant effects build with little warning. The safest course with codeine and alcohol is to keep them apart.

When the mixing is hard to stop

For some people, the two have become tangled together and hard to quit. Needing codeine and alcohol to get through the day, or finding you can’t keep them separate however much you mean to, is a sign that you may be addicted.

At Linwood House, we help people address alcoholism and codeine addiction with medical support for withdrawal during alcohol detox or codeine detox, and proper therapy and care for what is causing them. If any of this sounds familiar, reach out to us, and we can talk through what recovery can look like for you.