People with liver disease should use paracetamol (known as acetaminophen in the United States) with caution, according to a warning issued by a US hepatitis support agency. Paracetamol is very widely used without any ill effects, and is often recommended by doctors as a treatment to reduce fevers and other side-effects associated with interferon anti-HCV therapy.
Based on advice from the US Food and Drug Administration (FDA), which licences medicines in the US, the American hepatitis organisation, the HCV Advocate is advising people with chronic liver disease to take no more than the recommended daily dose of paracetamol and to avoid taking the pain-killing and fever reducing medication with even small amounts of alcohol.
Paracetamol, which is sold over the counter without prescription, is processed by the liver and in common with many anti-HIV drugs, uses the P450 enzyme. Large doses of paracetamol, or taking the painkiller with alcohol can overwhelm the liver's ability to process it and cause toxicities.
A safe dose of paracetamol in adults is four 400mg doses at regular intervals over a 24 hours period. Most people, even those with hepatitis B and C use paracetamol with no ill-effects and the US FDA says that the drug can still be used safely by people with chronic liver disease. However, it is stressing that dosing guidelines should be adhered to and that taking all the 1600mg daily recommended dose of paracetamol at once could cause liver injury. In addition, the FDA is recommending that people who drink two or three units of alcohol a day (a unit is equal to a half pint of beer, or a glass of wine or a pub measure of spirits) should cut their daily intake of paracetamol by half. People with cirrhosis are advised to avoid alcohol completely.
Other over the counter medication pain killing medication, such as aspirin, and ibuprofen are also known to have the potential for liver toxicities which are more severe than those caused by paracetamol.
Liver injury caused by paracetamol overdose has three stages. During the first twelve to 24 hours after taking the toxic dose, a person may experience nausea and vomiting. During the second phase, from 24-48 hours, a person usually feels better. After 48-72 hours, levels of the liver enzymes ALT and AST, which are indicative of impaired liver function begin to rise. In the most severe cases a person may develop acid buildup in the blood, excessive bleeding, and coma. At this stage, only a liver transplant can prevent death.
People taking paracetamol are recommended to keep track of their daily intake of the drug, and to check labelling of other drugs, such as cold and flu remedies to see if they contain paracetamol.
Further information on this website
The Liver Factsheet