Hangover sufferers beware! Don't take Tylenol after drinking!
Alcohol metabolism activates an enzyme that transforms acetamenophen into chemical compounds that cause liver damage. If you are a chronic drinker, use of over the counter pain relievers and fever reducers is likely to cause liver damage severe enough to require a liver transplant--not a risk worth taking!!
If you know you're going to be drinking and you want to preemptively treat hangover headache, take it well BEFORE you drink. Better yet, don't drink so much that you need it.
FDA ANNOUNCES NEW ALCOHOL WARNINGS FOR PAIN RELIEVERS AND FEVER REDUCERS
Alcohol Metabolism-Alcohol Alert No.35-1997
Dangers of Acetaminophen and Drinking