Codeine and Alcohol: Why This Combination Is Dangerous

Codeine and alcohol are both central nervous system depressants. Taken together, their effects do not simply add up — they compound in ways that can suppress breathing to a dangerous or fatal degree. The NHS advises that alcohol increases the risk of codeine side effects, and the FDA has required a black-box warning on all opioid products stating that combining them with alcohol can result in profound sedation, respiratory depression, coma, and death.

This is not a theoretical risk reserved for people who take large quantities of both. It can occur at lower doses than many people expect, particularly in those with any existing respiratory vulnerability. Understanding exactly what happens in the body, recognising the emergency signs, and knowing when a pattern of combining the two signals a dependence problem, can all make a genuine difference.

What Codeine Is and How It Works in the Body

Codeine is an opioid painkiller. On its own, it has relatively weak activity, but the body converts it into morphine in the liver through an enzyme called CYP2D6. According to a clinical reference published by the NIH, it is this conversion to morphine that produces most of codeine’s pain-relieving and sedating effects. Morphine acts at mu-opioid receptors in the brain and spinal cord, which not only reduces pain perception but also slows breathing.

Codeine is prescribed in the UK for moderate pain that does not respond to paracetamol or ibuprofen, for a dry or tickling cough, and sometimes for diarrhoea. It is available as tablets, capsules, and liquids.

In February 2024, the MHRA reclassified codeine linctus as a prescription-only medicine following a significant rise in cases of misuse, dependence, and overdose linked to the oral solution. Deaths involving codeine in the UK rose from 88 in 2011 to 200 in 2021, a trajectory the regulator found sufficiently serious to act on.

How Alcohol Acts on the Central Nervous System

Alcohol does not just make you feel relaxed. At a physiological level, it is a central nervous system depressant that slows neural activity across the brain and brainstem.

One of its most clinically significant effects is on the respiratory centre in the brainstem, which controls the automatic drive to breathe. Alcohol reduces the sensitivity of this centre, meaning the body’s normal signalling to maintain adequate breathing rates is blunted. In healthy adults at moderate doses, this effect is modest and self-correcting. The problem arises when a second substance with the same mechanism is introduced at the same time.

Alcohol is thought to act partly by enhancing GABA activity and reducing glutamate signalling in the brain. The net result is generalised slowing of brain activity, which at higher doses produces sedation, loss of coordination, and impaired consciousness. These are exactly the same directions in which opioids push the nervous system.

What Happens When You Combine Codeine and Alcohol

When two CNS depressants are taken together, their effects on the nervous system are additive. Both codeine and alcohol slow respiration, sedate, and impair consciousness. Combining them intensifies each of these effects beyond what either substance would produce alone.

The FDA issued a boxed warning in 2016 requiring all opioid products to carry the following statement: concomitant use of opioids with benzodiazepines or other central nervous system depressants, including alcohol, may result in profound sedation, respiratory depression, coma, and death. That warning applies to codeine.

The interaction is not dose-dependent in a simple, predictable way. A quantity of alcohol that would ordinarily produce mild intoxication in a given person can be enough to push codeine’s respiratory-depressant effect across a dangerous threshold. This is especially true because both substances are processed by the liver, and the liver cannot prioritise one over the other cleanly when both are present simultaneously.

The sedation produced by the combination can also impair a person’s ability to recognise that they are in trouble. Someone who has taken codeine and drunk alcohol may become deeply drowsy, lose consciousness, or stop breathing without any preceding warning they can act on themselves. This is one reason why the combination is particularly dangerous even in familiar quantities.

The Risk of Respiratory Depression and Overdose

Respiratory depression — breathing that becomes too slow, too shallow, or stops entirely — is the central mechanism by which opioid overdose kills. When the brainstem’s respiratory drive is sufficiently suppressed, the body simply fails to maintain the breathing it needs to stay alive.

The NIH’s clinical reference on codeine describes the classic opioid overdose triad as: abnormally slow or absent breathing, decreased or absent consciousness (coma), and pinpoint pupils (miosis). All three components reflect extreme CNS depression. Alcohol contributes to each of them.

There is an additional complication that is not widely known outside clinical settings. The conversion of codeine to morphine in the liver varies significantly between individuals depending on their CYP2D6 genetics. A proportion of people are what clinicians call ultra-rapid metabolisers, meaning they convert codeine to morphine considerably faster than average. This applies to a significant proportion of people with certain genetic backgrounds, with rates varying considerably across different populations. In these individuals, standard doses of codeine can produce morphine concentrations that would normally only result from a much higher dose. When alcohol is present as well, the respiratory risk is compounded further.

This genetic variation is not detectable without specialised testing, and most people do not know which metaboliser group they fall into. It is one reason why “I’ve taken this before without any problems” is not a reliable safety benchmark when alcohol is also involved.

Signs of a Codeine and Alcohol Emergency

If someone who has taken codeine and drunk alcohol shows any of the following signs, call 999 immediately. Do not wait to see whether they improve.

• Very slow, shallow, or irregular breathing, or breathing that has stopped
• Unresponsiveness: they cannot be woken by speaking loudly or shaking them
• Blue or grey colouring of the lips, fingertips, or face (cyanosis), indicating insufficient oxygen
• A gurgling or rattling sound with each breath
• Very small (pinpoint) pupils even in low light
• Cold, clammy, or pale skin
• Limpness in the body

While waiting for an ambulance: do not leave the person alone, place them in the recovery position if they are breathing, do not give them water or food, and keep them warm.

Naloxone (Narcan) is a medication that can rapidly reverse opioid overdose by blocking opioid receptors. In the UK, naloxone is a prescription-only medicine, but authorised drug and pharmacy services can supply it without a prescription under specific legal arrangements, and it is increasingly carried by community first responders. If naloxone is available and the person is unresponsive with very slow or absent breathing, administer it as instructed on the packaging and still call 999.

Who Is at Greatest Risk

Not everyone who takes a single codeine tablet and then has a drink will come to serious harm. But certain combinations of factors raise the risk substantially.

The NHS lists liver disease, asthma, sleep apnoea, and a history of substance use as conditions that may make codeine unsuitable. If any of these apply to you and you are currently prescribed codeine, speak to your GP about your alcohol intake so they can advise you appropriately.

When Codeine Dependence Develops

Opioid dependence does not always follow from recreational misuse. Many people who develop a dependence on codeine were doing exactly what their doctor prescribed. Physical dependence, where the body adapts to the presence of the drug and produces withdrawal symptoms when it is reduced, can develop within a matter of weeks even at standard therapeutic doses.

The signs that dependence may be developing include needing a higher or more frequent dose to achieve the same level of pain relief or comfort, experiencing anxiety or physical discomfort when a dose is due and not available, visiting multiple pharmacies or obtaining codeine from sources outside a single prescription, and continuing to use it beyond the original reason it was prescribed.

Psychological dependence follows a similar pattern: using codeine to manage emotional discomfort, stress, or mood rather than pain. This is not a character failing. It reflects how opioids interact with the brain’s reward system, producing a sense of ease or relief that becomes associated with the drug itself rather than the original problem.

Stopping codeine suddenly after regular use is not recommended and should not be attempted without medical guidance. Withdrawal produces physical symptoms that, while rarely dangerous in otherwise healthy adults, are very unpleasant, and abrupt cessation substantially increases the risk of relapse. Our prescription drug addiction treatment and heroin and opioid treatment programme cover the full range of opioid dependencies. The opioid addiction treatment page explains what medically supervised withdrawal involves and why it is the safer route.

When Alcohol Dependence Is Part of the Picture

For some people, combining codeine and alcohol is not occasional. It is a daily pattern, one substance reinforcing and amplifying the other. If you find yourself returning to this combination regularly, or if the thought of stopping one or both produces genuine anxiety, that warrants attention.

The NHS describes alcohol dependence as a condition in which the body has become used to functioning with alcohol present, making it physically and psychologically difficult to stop. Signs include drinking more than you intended, being unable to cut down despite wanting to, continuing to drink when it is clearly causing problems, and experiencing symptoms of physical withdrawal (sweating, shaking, nausea) when you try to stop.

Alcohol withdrawal, unlike codeine withdrawal, carries its own significant medical risks, including seizures and, in severe cases, delirium tremens. If you drink heavily and daily, stopping alcohol without medical supervision is not safe. This is a fact worth knowing, not a reason to keep drinking.

Our page on alcohol addiction covers the signs of dependence in more detail. If you have found it hard to cut back, or if you have been using alcohol and codeine together to manage discomfort or distress, you are not alone, and support is available.

Getting Help With Codeine or Alcohol: What Sierra Recovery Offers

Sierra Recovery is a small private residential clinic in the mountains of inland Andalucía, Spain, backed by PROMIS Clinics in the UK. We treat both opioid dependence and alcohol dependence in adults who are ready to stop and want clinical support to do it safely.

Our alcohol detox programme is medically supervised by a doctor, following NICE guidance: a controlled taper with nursing observation through the acute withdrawal phase, thiamine prophylaxis, and vital signs monitoring. Our residential treatment programme follows medical stabilisation with evidence-based therapy, including CBT, DBT, and EMDR, delivered in small groups and one-to-one sessions.

For people dependent on both opioids and alcohol, dual presentation is something we treat. Our clinical team, trained within the PROMIS model, is experienced with managing complex presentations including patients managing withdrawal from multiple substances.

The team is English-speaking throughout. Treatment is set in a restored Spanish cortijo in the mountains rather than a clinical facility on a high street, and aftercare, including in-person sessions through PROMIS UK’s London touchpoint, continues after you leave Spain. For many UK clients, this combination of clinical standard, private setting, and value relative to UK private care makes Sierra a serious option worth a conversation.

Concerned about codeine or alcohol use? Talk to our team in confidence. We answer questions about opioid and alcohol treatment honestly, in English. PROMIS Clinics-backed care, medically supervised detox, residential programme in Andalucía, London-based aftercare. Speak to our team UK: +44 1202 653136 | Spain: +34 666 777 888 Confidential. English-speaking team. No obligation.

Sources

1. NHS. “Codeine.” https://www.nhs.uk/medicines/codeine/
2. NIH StatPearls. “Codeine.” NBK526029. https://www.ncbi.nlm.nih.gov/books/NBK526029/
3. FDA. “New Safety Measures Announced for Opioid Analgesics, Prescription Opioid Cough Products, and Benzodiazepines.” https://www.fda.gov/drugs/information-drug-class/new-safety-measures-announced-opioid-analgesics-prescription-opioid-cough-products-and
4. MHRA / GOV.UK. “Codeine linctus: reclassification to prescription-only medicine.” Drug Safety Update, February 2024. https://www.gov.uk/drug-safety-update/codeine-linctus-codeine-oral-solutions-reclassification-to-prescription-only-medicine
5. NHS. “Alcohol-use disorder.” https://www.nhs.uk/conditions/alcohol-use-disorder/