Codeine is an opioid painkiller that depresses the central nervous system, causing drowsiness and slowed breathing. Alcohol does the same, so taking them together amplifies these effects and significantly raises the risk of dangerously slow or stopped breathing, profound sedation, and overdose.
This combination also increases the chance of falls, accidents, nausea, and impaired judgement. Many codeine products are combined with paracetamol, adding the separate concern of liver strain when alcohol is involved.
Do not drink alcohol while taking codeine, and do not drive or operate machinery until you know how it affects you. Seek emergency care immediately for very slow or shallow breathing, extreme sleepiness, blue lips, or unresponsiveness, as these are signs of opioid overdose; call your local emergency number.