If I've overdosed on Tylenol (acetaminophen) years ago n had Tylenol (acetaminophen) poisoning is it safe to ever take meds containing Tylenol (acetaminophen) again or could I never take it again?

May take. As long as it was a one time OD and you did not suffer long term liver damage, and you are NOT ALLERGIC to Tylenol, (acetaminophen) you can take the medication as directed.
Should be OK. Tylenol (acetaminophen) causes a chemical hepatitis when taken in excess. There are people who can have long term liver complications with Tylenol (acetaminophen) overdose or liver failure. If you have recovered and do not have any other liver problems taking a dose of Tylenol (acetaminophen) should not be a problem.