Acetaminophen is commonly used to treat fever or pain. Your body clears acetaminophen by processing it in the liver. During the processing, some of the acetaminophen may bind to proteins in the liver. The protein-acetaminophen product is called an "adduct". After a large acetaminophen overdose, the liver has to process a lot of acetaminophen, so large amounts of adducts are formed. However, we have found that lower levels may be formed even when people take recommended doses. The purpose of this study is to measure the amount of adducts formed when healthy people who do not drink alcohol take normal doses of acetaminophen for 10 days.

Inclusion Criteria:

1. age 21 years or older
2. provide written informed consent
3. consume, on average, less than 1 alcoholic beverage daily for the previous 3 months and would be considered non-drinkers

Exclusion Criteria:

1. History of ingesting more than 4 grams of acetaminophen per day for any of the four days preceding study enrollment
2. Currently taking isoniazid
3. Consumption of any alcoholic beverage during the run-in period
4. A detectable serum acetaminophen at baseline
5. Serum ALT or AST levels greater than 50 IU/L at the start of the run-in period or at baseline
6. Platelet count less than 125,000/cc at baseline
7. Positive pregnancy test at baseline (female participants only)
8. Currently adheres to a fasting type diet as determined by self report
9. Currently has anorexia nervosa as determined by self report
10. Subject appears clinically intoxicated, psychiatrically impaired or unable to give informed consent for any reason
11. Known hypersensitivity to acetaminophen