Actually ibuprofen is mainly metabolized by the kidneys, but Tylenol/acetaminophen is metabolized by the liver and can be quite deadly to people with compromised liver function. When I was working at the hospital we had a man in his mid-40s come in through the emergency room who was orange because of liver failure, who never woke up from his coma. He had had a bad cold, and had double dosed cold medicine that had acetaminophen in it, and also take Tylenol, just trying to get to sleep so he could get to work in the morning. He had some sort of liver disease, I don't remember if it was cirrhosis or something else, and unintentionally killed himself with acetaminophen, trying to relieve symptoms of a cold. It was heartbreaking.
Also, Kiki's reminders to you to modify your lifestyle is one of the most loving things I've ever witnessed; that someone cares so much about a virtual stranger almost two thousand miles away doesn't happen for a lot of people.