Any drug has the capacity to alter the metabolism or absorption of alcohol (so potentially increasing intoxication), and
alcohol itself may equally alter the metabolism and absorption of any drug (so reducing the action of the drug or increasing its toxicity). Furthermore, the drug alcohol combination itself can produce serious adverse reactions: liver damage, gastrointestinal inflammation and bleeding, violent nausea and vomiting, excessive sedation and delirium have all been reported (Int J Addict, 1995; 30: 1903-23). Chronic alcohol use may cause drugs to have paradoxical effects, particularly among alcoholics (Ann Med, 1990; 22: 363-9).
Don't assume your doctor is God:
Even with prescription medicines, your doctor may not consider potential interactions. Make sure he does. In the UK, all doctors should have the regularly updated British National Formulary to guide them (the Physicians' Desk Reference in the US).
Take care with self prescribing:
Non prescription over the counter medicines are still drugs. Read the small print to check for interactions, and warn your pharmacist or doctor what you are taking.
Take care with herbal remedies:
Herbs contain powerful drugs, and we still have only a rudimentary knowledge of their effects and potential interactions (see PROOF! vol 3 no 3).
Beware of hospitals:
If you're in hospital, tell your doctors and, if having surgery, your anaesthetist what you're taking; some drugs can seriously interact with anaesthetics, particularly antibiotics and antidepressants, such as the tricyclics and MAO inhibitors (J Clin Anesth, 1997; 9: 3S-13S). Deaths have been reported from the interaction between anaesthetic drugs and tetracycline antibiotics (JAMA, 1970; 211: 1162).