Apparently a common source of problems is taking two different medications without realizing they both contain acetaminophen.

Suppose your arthritis is acting up, so you start taking Tylenol 8hr Arthritis Pain[1]. That's 2 tablets every 8 hours. They're extended-release with 650mg per tablet. A total of 3900 mg in 24 hours.

A few days later you get the flu, so you decide to add what seems like a completely different medication: Theraflu Flu Relief Max Strength[2]. It has a cough suppressant and an antihistamine. But each caplet also contains 500 mg of acetaminophen. It says to take 2 caplets every 6 hours, so you take 8 of them in 24 hours[3]. That's another 4000 mg.

Between the two, you're at 7900 mg.

Then you wake up in the morning and take both medications, but 30 minutes later you've forgotten you took them. You're not thinking straight because you're sick. So you accidentally take a second dose. That additional 2300 mg brings your total to 10200 mg.

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[1] https://www.tylenol.com/products/arthritis/tylenol-8hr-arthr...

[2] https://www.theraflu.com/products/day-night-flu-relief-max-s...

[3] You weren't supposed to take 8 of them, though. If you'd read the label very carefully, you'd have seen it also says not to exceed 6 in a 24-hour period.