Acetaminophen is widely available without prescription. It is available in North America as Tylenol (see below), among other names. It is used to treat many minor health problems, including toothaches, muscle and joint pain, backaches, headaches and period pain.
Acetaminophen is about as effective as aspirin, but has almost no anti-inflammatory activity. This means it deadens the feeling of pain, but does not do anything to get rid of the condition which is causing the pain. Compare this to ibuprofen, an NSAID which acts to reduce inflammation.
Acetaminophen is now the leading cause of acute liver failure in the U.S., mainly due to accidental overdoses, whether by exceeding the recommended dosage, or combining two products with acetaminophen/paracetamol as the primary ingredient. An overdose, and permanent liver failure, can occur simply by taking 10 grams (20 pills) a day for three days once.
As with all therapeutic drugs, you should always adhere to the dosage guidelines which accompany the drug.
Tylenol is a trademarked commercial preparation of acetaminophen, which is only available in North America.
As a point of interest, Tylenol is also behind both anti-tampering laws and tamper-proof safety seals on many ingestable products, due to the Chicago Tylenol Murders. In 1982, seven people died after ingesting cyanide-laced Extra Strength Tylenol capsules. The culprit, who was never caught, was thought to have bought several bottles from different supermarkets and pharmacies, replaced the capsules with cyanide, and placed the bottles at other locations, where they were later purchased by the victims. Five bottles were involved in the victims' deaths, and another three were found to have been tampered with.