Ethical dilemma: A delay starting antibiotics

At the end of the day, it's the patient's choice as to whether he follows your (correct) advice. Of course you would advise the patient against drinking and to take the antibiotics as soon as possible, in line with his GP's recommendations. As for the consequences, you've done your part in line with duty of care, as soon as he leaves, it's his responsibility, not yours.

Referring to good practice guidelines,the pharmacist would produce a cautionary label indicating AVOID ALCOHOL WITH THIS ANTIBIOTIC.When handing out the dispensed prescription the pharmacist would verbally explain the cautionary label and perhaps the consequencies of the reaction of alcohol and metronidazole.
In this case the patient would be taking a risk if he does not follow Pharmacist s advice.In my opinion the risk of interaction far outweighs the stag do .

he should take it after 48 hours.

not an uncommon problem - I always counsell about alcohol and metronidazole, patients are either off to a party / wedding / celebration/ holiday or are teetotal. I would give him 2 alternatives - if his infection is severe, start now and don't drink; if he may not need antibiotics (we see a lot of delayed rxs these days) then wait 48 hours after his last alcoholic drink and then decide if he needs to take them at all

This article pretty much summed up Christmas in a nutshell for me at one of the pharmacies. I agree completely with Mr Anwar. As the saying goes, you can lead a horse to water, but you can't make him drink. Or not in this case.