Q I'm hearing news about the dangers of taking too much acetaminophen (Tylenol, etc.). I thought it was the safest pain-reliever. Would you comment?
A Acetaminophen, the popular over-the-counter pain and fever remedy, possesses a Jekyll and Hyde personality.
At recommended doses it's one of the safest drugs. In excessive doses, it can seriously damage the liver.
In fact, acetaminophen overdose is the No. 1 cause of acute liver failure.
A recent analysis found that, over a six-year period, the incidence of acetaminophen-induced liver failure spiked dramatically, going from 28 percent to 51 percent of all cases. A striking number of these cases were intentional overdoses (suicide attempts), underscoring how lethal excessive amounts are.
Accidental overdoses, on the other hand, were responsible for almost half the cases. These involved people taking two or more acetaminophen-containing products at the same time or prescription narcotic pain relievers containing acetaminophen.
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Of those with acetaminophen-induced liver failure, 35 percent died, including some who had undergone a liver transplant.
Clearly, people need to sharpen their acetaminophen antennae.
It may help to know how Dr. Jekyll morphs into Mr. Hyde. At recommended doses, things proceed without a hitch: The liver breaks down acetaminophen for removal from the body.
Excessive doses, however, can overwhelm the liver, causing it to shift to an alternate breakdown route. This secondary route produces a liver-toxic compound. Ordinarily, a protective body substance called glutathione rides to the rescue and muzzles the harmful compound. But the acetaminophen overload rapidly depletes the available glutathione, allowing the toxic chemical to build up unchallenged.
At what level does acetaminophen pass from the safe zone into the danger zone? The generally recognized cut-off point is 4,000 mg over a 24-hour period.
To stay in the safe zone, avoid taking more than 4,000 mg at one time, or taking lower doses several times daily that exceed a total of 4,000 mg. Over-the-counter "extra-strength" acetaminophen pills contain 500 mg, so eight pills takes you to the ceiling limit of 4,000 mg.
Be aware that many narcotic pain-relievers also contain acetaminophen, including Anexsia, Darvocet N-100, Lortab, Lorcet and Vicodin.
These prescription products contain substantial amounts of acetaminophen — from 500 mg to 750 mg per pill. They are prescribed for moderate pain to be taken at intervals of four to six hours when necessary.
Taking more than eight pills of the 500 mg products or more than five pills of the 750 mg products in a 24-hour period puts you in the danger zone.
Keep in mind that more than 200 over-the-counter products contain acetaminophen, including remedies for pain, fever, allergy, and cold and cough.
Protect yourself by adding up your total daily dose of acetaminophen. Check product labels and count amounts from all sources.
Extra caution is warranted for chronic heavy users of alcohol and individuals with impaired liver function.