Can taking too much of a household medicine, like Tylenol, DayQuill, Robitussin, etc. be lethal?

Of course! For example, Tylenol should not be overdosed inasmuch as it is very "damaging" to the human liver! Max dosage for Tylenol is 4000 mg/day! When this med is being overdosed: (Tylenol only). The following might happen: hepatic seizure, renal failure, rash, jaundice, delirium followed by vascular collapse, convulsions, coma, death.

Offcourse they are lethal. Do not take medicine for small small pain. Let your body immune system fight against it. All these medicines are nothing but pain killers they just supress the pain or irritation. Even when you take these medicines they just kill the pain rest is all done by your immune system. And these pain killers are having there own side effects to human body. regards

YES it can. If you take enough. I was once hospitalized from trying to kill myself with Tylenol PM. I was stupid I know. I started to feel myself slip away & was barely able to talk to poison control but they got me an ambulance & by some miracle I didn't have to have my stomach pumped.

Tylenol (acetaminophen) is a major cause of death due to liver failure in the United States. Dosing information for acetaminophen products does not properly protect the user since a fraction of acetaminophen is turned into a cell toxic poison, NAPQI. The liver cells and other cells can make a store an antidote to NAPQI like poisons called glutathione. But those cells can only store only a limited amount of glutathione and it takes time to make more glutathione. When the glutathione is depleted but the NAPQI keeps coming, then the liver gets killed off. You can lose a bit of your liver time after time and not notice a problem, until its too late. Diet, and the individual's previous history of drug/alcohol use determines whether or not your liver is damaged when taking acetaminophen. The link below is from the Merck Manual, it give the facts but keep in mind its published by a drug company, so the dosing information is probably too high. http://www.merck.com/mmpe/sec21/ch326/ch326c.html?qt=acetaminophen poisoning&alt=sh