Here we have a highly addictive drug (codeine) that is otherwise reasonably safe in quite high doses, and that is regularly prescribed in substantially higher doses. E.g. prescription co-codamol is usually sold with 30mg codeine per 500mg paracetamol vs. 8 or 12.5 mg codein in over the counter, and you can get prescriptions for "neat" codeine at higher doses as well.
And we have a drug that causes liver failure in quite small doses, to the extent that the UK government put in place restrictions on it sale intended to reduce its use in suicides (you can only buy 16 pills at a time outside of pharmacies, and 32 pills at a time in a pharmacy). It's been widely reported to have cut suicide deaths using paracetamol by hundreds (total, not per year) since the restriction was put in place as just that slight little barrier of having to go to multiple places is apparently enough to make some people think twice.
So what do they do? Of course, since we all know addiction is bad (and we're talking religious/morally/tabloid style righteous "bad" here), why, when they decide to allow sales of tablets with codeine over the counter, they decide it should be mixed with paracetamol or ibuprofen, with the codeine content low enough that anyone left addicted after failing to get prescriptions renewed etc. faces the choice of suffering it out, or risking their liver.
Cue a couple of years, and the warnings about the danger of these pills are starting to emerge: Surprise, surprise, people with severe opiate addictions are sufficiently often not in a place where you should expect them to make rational decisions about whether or not taking products containing too much paracetamol is a good idea...
I get migraines sometimes, and the codeine/paracetamol pills are a great help, but I can't help but think that allowing the over-the-counter sale of them without a "safe" alternative for those addicted to codeine is tantamount to murder - the government knew all the risks, and in fact there'd be little reason to require those mixes over allowing plain codeine if it wasn't as a way of making the pills more dangerous to abuse. Yet they did it anyway.