Paracetamol and Alcohol

Last week I attended a fantastic course in London called Pain and Pharmacology. You might be interested to know what I learnt about Paracetamol and Alcohol.

Paracetamol like most medications is metabolised mainly by enzymes in the liver. Paracetamol goes through two consecutive phases of metabolization, after the first phase it becomes very toxic to the cells of the liver but this is usually immediately rectified after the second phase of metabolization is complete. During paracetamol overdose one of the key issues is the that there are insufficient enzymes to maintain the second phase metabolization and the toxic partially metabolised paracetamol causes toxic damage to the liver. Indeed, treatment for paracetamol overdose required giving patients an enzyme inducing agent to help the liver cope with completing metabolizing the toxic partially metabolised paracetamol.

Interestingly I learned that alcohol also competes with paracetamol for the same metabolising enzymes, hence why alcohol can be a significant aggravating variable in overdose. Also, however because drinking alcohol at same time as taking paracetamol will mean partially metabolised paracetamol will remain in its toxic form for longer and therefore is potentially harmful to the liver. It’s not exactly known how much damage this will cause or for how long this would be repeated before causing significant harm but this is probably something we should be advising our patients to avoid if at all possible. We know from research that a concept known as ‘staggered overdosing’ occurs whereby people take more than the recommended levels of paracetamol (greater vthan 4g every 24 hours) and often this correlates with people also drinking alcohol along side – this can be damaging over a period of time.

So my advice is do not take Paracetamol before you head for the pub or before you go to bed for a hang-over cure. There is no medication cure to prevent a hangover. You simply have to wait till your liver is clear of the alcohol.

Ref: Pain & Pharmacology Lecture with David Baker, UCO and A competency Framework for all Prescribers 2016