A couple of days ago I bought a bottle of Walmart’s brand of acetaminophen. At the top of its packaging was a banner that read: “See new warnings and directions.” So I took a look and found that in contradistinction to previous labeling the user was directed not to take more than 3,000 mg daily in four divided doses. The reason? “Severe liver disease may result if you take more than 4,000 mg of acetaminophen in 24 hours.” So why not limit the daily intake to 4,000 mg which is what the recommended dose for pain relief has always been? Briefly there is no good reason. I’ll come back to this below.

I went to Tylenol’s web site. Tylenol is the brand name of the most familiar formulation of the drug. Sure enough there was a page devoted to “New Tylenol Dosing Instructions.” It had the same maximum dose for acetaminophen. They gave a reason:

Today, more than 600 over-the-counter and prescription medicines contain acetaminophen. These include medicines to treat symptoms of allergies, cold and flu, and pain with trouble sleeping.

Some people accidentally exceed the recommended dose when taking multiple products at the same time, often without realizing they contain acetaminophen or by not reading and following the dosing instructions. Acetaminophen –the active ingredient in TYLENOL® products–is safe when used as directed, but when taken in overdose amounts, it can cause liver damage.

Translating this to English yields this. We don’t think the public is smart enough to figure out that other pain killers may have acetaminophen in them. And they may take acetaminophen from the combination of pain killers so that their daily dose exceeds 4,000 mg. Thus we’ll build in a safety margin by telling the users of Tylenol and it like not to take more than 3,000 mg and hope for the best. That 3,000 mg a day for patients with osteoarthritis likely will not give adequate pain relief is irrelevent. Also, we (McNeil) don’t want to be sued (again) if one of our customers gets liver disease while taking Tylenol.

I know of no example of a single patient who didn’t have liver disease to start with and who did not exceed 4,000 mg of acetaminophen a day and who wasn’t a heavy drinker getting liver disease from the drug. The Mayo Clinic offers much more sensible advice about how to take this drug:

Take this medicine only as directed by your doctor. Do not take more of it, do not take it more often, and do not take it for a longer time than your doctor ordered. If too much of this medicine is taken for a long time, it may cause an overdosage. Liver damage can occur if large amounts of acetaminophen are taken for a long time.

Carefully check the labels of all other medicines you are using, because they may also contain acetaminophen. It is not safe to use more than 4 grams (4,000 milligrams) of acetaminophen in one day (24 hours).

You may take this medicine with or without food.

If you are taking this medicine without the advice of your doctor, carefully read and follow the drug facts label and dosing instructions on the medicine package. This is to avoid confusion and dosing errors. Ask your doctor if you have any questions.

Instead of the belt an suspenders approach read the label on any medicine you’re taking so that you don’t take too much of whatever drug you’re on. The new labeling which follows pressure from the FDA is going to confuse a lot of people and result in insufficient pain relief. Interestingly, the FDA still gives the maximum dose for this drug as 4,000 mg daily. The agency’s recommendation that the maximum dosage unit be lowered from 500 mg to 325 has not been followed. This makes for an interesting analysis of the relationship between the FDA and the pharmaceutical industry that I will leave you to figure out for yourself.