In this Article

• "Is it safe for me to take Tylenol?"
• Do the recommended doses of Tylenol cause any liver damage?
• Why should we know that the generic name of Tylenol is acetaminophen?
• Just how much acetaminophen is safe to take?
• How is acetaminophen processed (metabolized) in the body?
• How does an overdose of acetaminophen cause liver injury?
• Is overdose with acetaminophen usually accidental or intentional?
• How can accidental overdose be avoided in adults?
• How can overdose be avoided in children?
• What are the symptoms and signs of acetaminophen-induced liver damage?
• What should be done if acetaminophen toxicity is suspected?
• Acetaminophen (Tylenol) Liver Damage At A Glance
• Tylenol Liver Damage Glossary
• Tylenol Liver Damage Index

How is acetaminophen processed (metabolized) in the body?

The liver is the primary site in the body where acetaminophen is metabolized. In the liver, acetaminophen first undergoes sulphation (binding to a sulphate molecule) and glucuronidation (binding to a glucuronide molecule) before being eliminated from the body by the liver. The parent compound, acetaminophen, and its sulphate and glucuronide compounds (metabolites) are themselves actually not harmful. An excessive amount of acetaminophen in the liver, however, can overwhelm (saturate) the sulphation and glucuronidation pathways. When this happens, the acetaminophen is processed through another pathway, the cytochrome P-450 system. From acetaminophen, the P-450 system forms an intermediate metabolite referred to as NAPQI, which turns out to be a toxic compound. Ordinarily, however, this toxic metabolite is rendered harmless (detoxified) by another pathway, the glutathione system.

How does an overdose of acetaminophen cause liver injury?

The answer is that liver damage from acetaminophen occurs when the glutathione pathway is overwhelmed by too much of acetaminophen's metabolite, NAPQI. Then, this toxic compound accumulates in the liver and causes the damage. Furthermore, alcohol and certain medications such as phenobarbital, phenytoin (Dilantin), or carbamazepine (Tegretol) (anti-seizure medications) or isoniazid (INH, Nydrazid, Laniazid) - (anti-tuberculosis drug) can significantly increase the damage. They do this by making the cytochrome P-450 system in the liver more active. This increased P-450 activity, as you might expect, results in an increased formation of NAPQI from the acetaminophen. Additionally, chronic alcohol use, as well as the fasting state or poor nutrition, can each deplete the liver's glutathione. So, alcohol both increases the toxic compound and decreases the detoxifying material. Accordingly, the bottom line in an acetaminophen overdose is that when the amount of NAPQI is too much for the available glutathione to detoxify, liver damage occurs.

Tylenol Liver Damage - Symptoms Experienced

The MedicineNet physician editors ask:

What were the first symptoms of the liver damage you experienced from Tylenol?

Anonymously share your comment to help others.
Be the first to submit a comment

Submit Your Comment

Suggested Reading by Our Doctors

• acetaminophen, Tylenol and Others - Describes the medication acetaminophen (Tylenol) a drug used to relieve pain and reduce fever. Article includes descriptions, uses, drug interactions, and side effects.
• Liver Blood Tests - Learn about liver blood tests used to detect liver damage disease such as fatty liver, cirrhosis, hepatitis, Tylenol liver damage, and more. This includes measuring the aminotransferases enzymes (AST and ALT levels)
• Abdominal Pain - Learn about abdominal pain (pain in the stomach / abdomen) including causes, symptoms, how abdominal pain is diagnosed, and how abdominal pain is treated.

Read more Tylenol Liver Damage related articles »

Latest Medical News

• Boomers Doomed to Disability?
• Gender Divorce Gap After Illness Strikes
• Cigarette Smoking's Decline Levels Off
• 22 Million Cases of Swine Flu in U.S.