Is tylenol (acetaminophen) threes mixed with alcohol lethal?

DEPENDS ON AMOUNT: It can be lethal if both are taken in excess.Alcohol in large amount can be rarely lethal and so is codein and acetaminophen(tylenol 3 contains Codeine and acetaminophen)alcohol and Acetaminophen in large quantitiy are toxic for liver and in large amounts can cause liver failure and large doses of Codeine can cause respiratory depression so it depends on amount ingested in combination.