Acetaminophen 500 milligrams is an over-the-counter, extra-strength dose, according to the Tylenol website. At a 500 milligram dose, users should not take more than six caplets in 24 hours.
Acetaminophen is sold in multiple over-the-counter doses, as stated by the Tylenol website. Regular-strength acetaminophen is dosed in 325 milligram tablets every four to six hours. Extra-strength acetaminophen is dosed at 500 milligrams every six hours. Acetaminophen for arthritis is dosed at 650 milligrams every eight hours.
Do not exceed the maximum daily dose of 4,000 milligrams, says the Food and Drug Administration. Taking more than the maximum recommended dose of acetaminophen in a 24-hour period can cause acetaminophen-related liver failure and lead to liver transplant or death.