A friend whose judgement I trust implicitly was talking recently about her niece who is a doctor in the UK. My friend also trusts her niece's judgement implicitly, so therefore so do I.
Anyway, the point is, this doctor had been kvetching about people who misuse everyday drugs (think, acetaminophen, iboprofin) by not taking as much as they were allowed, according to the label. They may be worried about overdosing, or concerned about developing a tolerance, a dependence, an addiction, that kind of thing.
Well, my wife is that kind of cautious drug-user. So, given that she is now having to rely on extra-strength Tylenol (acetaminophen) to mask some pretty severe back pain, at least until her appointment with a pain management clinic comes through, I decided to check on the dosage rules and recommendations.
According to Harvard Health Publishing, which I'm also inclined to trust, one should "be cautious but not afraid" of Tylenol, and trust the dosage information on the label. Yes, people occasionally suffer liver damage and some even (very occasionally) die from overdoses, but you'd have to work very hard at it.
Some small portion of the drug is converted in the body to a by-product that is toxic to the liver, but you'd have to take an awful lot to build up more than the body can handle. Also, unlike NSAIDS (ibuprofen/Advil and naproxen/Aleve), high doses of acetaminophen will not irritate the stomach and intestinal lining. As for President Trump and Robert F. Kennedy's conspiracy theories about Tylenol, treat them with the contempt they deserve.
The maximum recommended daily dose of acetaminophen is 4,000 milligrams (mg) from all sources, although 3,000 mg is recommended, to be on the safe side.
So, if you are taking regular (325 mg) tablets, no more than 8 to 10 a day are recommended. The label suggests 1 or 2 tablets every 4 to 6 hours, which is about at the top end of the recommended daily dosage (although few people would continue taking them every 4 hours overnight, I think).
Extra-strength tablets are 500 mg, and no more than 6 a day are recommended. The label suggests 1 or 2 tablets every 6 to 8 hours. Some extra-strength tablets (e.g. for arthritis) are 650 mg, and no more than 4 a day are recommended. The label says take 1 every 8 hours (i.e. 3 a day).
So, as can be seen, the recommended dosages are quite conservative, and you'd have to be flouting them pretty cavalierly to run any risk at all of liver damage. So, don't skimp, take the recommended doses. You'll feel better and you're very, very unlikely to do any damage to your internal organs.