Toxic, Drug, or Chemically-Induced Hepatitis
The liver is responsible for the metabolism of alcohol, drugs, and environmental toxins. It breaks them down into substances that can be used and/or then eliminated from the body. Certain drugs, chemicals, and toxins can cause liver damage whenever a person is exposed to them. At times, the symptoms of toxic hepatitis can appear quickly, within hours or days of exposure to the substance, or sometimes develop slowly over time after repeated use of a drug or exposure to a chemical.
Acetaminophen, which is found in numerous over-the-counter and prescription medications, is an example of a drug that can cause toxic hepatitis. In therapeutic doses, it is a useful pain reliever, but in very high dosages or in combination with alcohol, it has the potential to cause life-threatening acute liver failure.
Excessive consumption of alcohol is a common cause of this type of hepatitis. It may be chronic yet mild, lasting for years but with no specific symptoms. However, over time, the liver may sustain more and more damage. The rate of mortaility in severe cases is about 50%. The damage may be reversed if alcohol consumption is stopped.
Many drugs have the potential to cause hepatitis in a few people, in a seemingly random fashion. Their effect cannot be foreseen and appears to be related to an allergic reaction to the medication. Drugs that have most commonly had this effect in a small number of people include anesthetics, antibiotics, anabolic steroids, and seizure medications.
Signs and Symptoms of toxic hepatitis vary depending on the cause. They may appear suddenly or may develop gradually over time with prolonged exposure to the drug or toxin. When present, they often correspond to the signs and symptoms of hepatitis in general. See the section on Signs and Symptoms for detailed information.
Drug, alcohol, and chemical-induced hepatitis are not typically tested for directly with laboratory tests. The diagnosis is often arrived at by examining the patient, getting a full medical history, especially about previous ingestion of chemicals, drugs, and/or alcohol, and, where applicable, evaluating hazards the patient may have been exposed to in the workplace, such as industrial solvents. There are some tests that may be performed to help evaluate someone with toxic hepatitis:
- Liver panel – to detect and/or determine the extent of liver damage
- Ethanol level – if alcohol is suspected to be a cause
- Emergency and overdose drug testing – including tests for drugs of abuse, acetaminophen, and therapeutic drugs to help determine the cause of hepatitis and guide treatment
There is no specific treatment for most kinds of toxic hepatitis. Usually, discontinuing the medication that is causing the liver damage or avoiding exposure to toxins is the first step. Many people fully recover from this type of hepatitis if this is done soon enough, although it may take months for the liver to heal. Occasionally, there is lasting damage such as cirrhosis and even liver failure. If the liver is irreversibly damaged, then a liver transplant may be an option.
There is treatment available for an overdose of acetaminophen that can minimize damage to the liver. N-acetylcysteine (NAC) may be given as an antidote within 24 hours of ingestion. It is most effective as an antidote if given within 8 hours of ingestion, so it is important to identify and treat this condition as soon as possible.