What are the first things that should be done for someone who has overdosed on tylenol (acetaminophen)?

911: An overdose of Acetaminophen (tylenol, also found in many over-the-counter cold/flu remedies and other meds) can be deadly, and deserves a 911 call. If it looks that there may be a delay and the overdose was within a few hours, vomiting can be induced but 911 still must be called as there could still have been significant absorption from the stomach, enough to seriously damage the liver.

Acetominophen OD: I agree with Dr. Puppala. Overdoses with acetaminophen are potentially fatal. Get emergency medical care.