Tylenol PM isn’t a single medication. It’s a combination of two drugs working together:
Acetaminophen, which reduces pain and fever
Diphenhydramine, an antihistamine that causes drowsiness
On the surface, it sounds convenient—relief from pain and help with sleep in one dose. But Dr. Melillo cautions that this convenience may hide real risks, particularly with frequent or long-term use.
Acetaminophen: Quietly Hard on the Liver
Acetaminophen—the same ingredient found in regular Tylenol—is one of the most widely used pain relievers in the U.S. It’s inexpensive, easy to find, and easier on the stomach than drugs like ibuprofen. However, it places a heavy burden on the liver.
When you take acetaminophen, your liver processes it. During that process, a small amount of a toxic byproduct called NAPQI is produced. Under normal circumstances, your body neutralizes this toxin using an antioxidant called glutathione, preventing harm.
The problem arises when that system is pushed too far—especially with repeated use, high doses, or mixing with alcohol—leaving the liver vulnerable.
But if you:
Take too much acetaminophen in one day,
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