Average 3 to 6 hours. Acetaminophen, the main ingredient in medications such as tylenol, (acetaminophen) is a medication that is quickly absorbed in our gastrointestinal tracts. The average time for it to "start working" is anywhere from 10 to 30 minutes, and the average time it stays in your body is anywhere from 4 to over 8 hours. In children it may be less time and in infants longer. Everybody absobs medicine differently.
Tylenol. Tylenol is dosed every 4 to 6 hours and that is about the time it's effect is felt to last. You can also get information about medications from your pharmacist.
Tylenol (acetaminophen) PM. Tylenol (acetaminophen) pm consists of Acetaminophen and Diphenhydramine is a combination medicine used to treat headache, runny nose, sneezing, watery eyes, and pain or fever caused by allergies, the common cold, or the flu. It typically lasts 6-8 hours, but can be shorter or longer dependent on how your body metabolizes these drugs. Read more...