Many drugs can affect the way the liver functions, damage the liver, or do both. (See also Drugs and the Liver Drugs and the Liver The body must process (chemically alter, or metabolize) drugs to be able to use and eliminate them. Most of this processing occurs in the liver, done by liver enzymes. Thus, drugs and the liver... read more .)
Some drugs, such as statins Lipid-lowering drugs Dyslipidemia is a high level of lipids (cholesterol, triglycerides, or both) or a low high-density lipoprotein (HDL) cholesterol level. Lifestyle, genetics, disorders (such as low thyroid hormone... read more 
(used to treat high cholesterol), can increase the levels of liver enzymes and cause liver damage (usually minor) but no symptoms. However, doctors may continue to prescribe statins for people with chronic liver diseases (for example, nonalcoholic fatty liver disease Fatty Liver Fatty liver is an abnormal accumulation of certain fats (triglycerides) inside liver cells. People with fatty liver may feel tired or have mild abdominal discomfort but otherwise have no symptoms... read more [NAFLD], nonalcoholic steatohepatitis Fatty Liver Fatty liver is an abnormal accumulation of certain fats (triglycerides) inside liver cells. People with fatty liver may feel tired or have mild abdominal discomfort but otherwise have no symptoms... read more [NASH], and NASH cirrhosis Cirrhosis of the Liver Cirrhosis is the widespread distortion of the liver's internal structure that occurs when a large amount of normal liver tissue is permanently replaced with nonfunctioning scar tissue. The scar... read more 
), because:
Statins pose no additional risks for these people than for those with no liver disease.
There are benefits of statin use for treatment of high cholesterol in people with NAFLD and NASH.
Statins are not, however, prescribed for people who have decompensated cirrhosis Cirrhosis of the Liver Cirrhosis is the widespread distortion of the liver's internal structure that occurs when a large amount of normal liver tissue is permanently replaced with nonfunctioning scar tissue. The scar... read more (an advanced stage of cirrhosis in which the liver can no longer function properly).
A very few drugs damage the liver enough to cause symptoms, such as a yellow color of the skin and eyes ( jaundice Jaundice in Adults In jaundice, the skin and whites of the eyes look yellow. Jaundice occurs when there is too much bilirubin (a yellow pigment) in the blood—a condition called hyperbilirubinemia. (See also Overview... read more 
), abdominal pain, itching, and a tendency to bruise and bleed.
Doctors use the term drug-induced liver injury (DILI) to refer to any liver damage caused by medications, whether it results in symptoms or not. The term also includes damage caused by recreational drugs Recreational Drugs and Intoxicants , medicinal herbs, plants, and nutritional supplements Overview of Dietary Supplements Dietary supplements are used by about 75% of Americans. They are the most common therapies included among integrative medicine and health (IMH) and complementary and alternative medicine (CAM)... read more .
For some drugs, liver damage is predictable. It occurs shortly after the drug is taken and is related to the drug's dose. In the United States, such damage (often caused by acetaminophen poisoning Acetaminophen Poisoning Acetaminophen, a common ingredient in many prescription and non-prescription drugs, is safe in normal doses, but severe overdose can cause liver failure and death. People sometimes ingest too... read more ) is one of the most common causes of the sudden appearance of jaundice Jaundice in Adults In jaundice, the skin and whites of the eyes look yellow. Jaundice occurs when there is too much bilirubin (a yellow pigment) in the blood—a condition called hyperbilirubinemia. (See also Overview... read more , liver failure Liver Failure Liver failure is severe deterioration in liver function. Liver failure is caused by a disorder or substance that damages the liver. Most people have jaundice (yellow skin and eyes), feel tired... read more , or both. For other drugs, damage is unpredictable. It is detected some time after the drug is taken and is not related to the dose. Rarely, such damage results in a severe liver disorder.
Medicinal herbs and the liver
Some medicinal herbs (parts of plants used for health benefits) contain substances that can damage the liver. The liver is a prime target for damage because it processes everything that enters the mouth and is swallowed.
Pyrrolizidine alkaloids: Hundreds of herbs contain pyrrolizidine alkaloids, which may damage the liver. These herbs include borage, comfrey, and certain Chinese herbs, such as zi cao (groomwell), kuan dong hua (coltsfoot), qian li guang (liferoot), and pei lan (Eupatorium). Some herbs used to make teas contain pyrrolizidine alkaloids. Sometimes milk, honey, and cereals are contaminated with pyrrolizidine alkaloids, which are then consumed unknowingly.
Pyrrolizidine alkaloids can damage the liver gradually if small amounts are consumed for a long time. Damage can occur more quickly if a large amount is consumed. The hepatic veins may become clogged, blocking blood flow out of the liver.
Affected people have abdominal pain and may vomit. Fluid accumulates in the abdomen and legs. Eventually, scar tissue in the liver ( cirrhosis Cirrhosis of the Liver Cirrhosis is the widespread distortion of the liver's internal structure that occurs when a large amount of normal liver tissue is permanently replaced with nonfunctioning scar tissue. The scar... read more ), liver failure Liver Failure Liver failure is severe deterioration in liver function. Liver failure is caused by a disorder or substance that damages the liver. Most people have jaundice (yellow skin and eyes), feel tired... read more , and even death may result.
Other herbs: Liver damage may also result from herbs such as Atractylis gummifera, Camellia sinensis (used to make green and black teas), celandine (in the poppy family), chaparral, Garcinia cambogia (a supplement used to support weight loss), green tea extract (used for weight loss and disease prevention), germander, jin bu huan, kava, ma huang (Ephedra), mistletoe, pennyroyal oil (used to make teas), and syo-saiko-to (a mixture of herbs).
In general, liver doctors recommend avoiding all herbal supplements because of the lack of safety testing by the US Food and Drug Administration (FDA) and the fact that many of these substances can cause liver damage and even liver failure, even in people who do not have any preexisting liver disease.
Risk factors
Generally, the risk of liver damage by drugs is thought to be increased by the following:
Age 18 years or over
Obesity
Pregnancy
Consumption of alcohol
A genetic makeup that makes people more susceptible to a drug's effects
Drinking alcohol increases the risk of liver damage because alcohol damages the liver Alcohol-Related Liver Disease Alcohol-related liver disease is liver damage caused by drinking too much alcohol for a long time. In general, the amount of alcohol consumed (how much, how often, and for how long) determines... read more and thus changes the way drugs are metabolized. In addition, alcohol reduces the body's supply of an antioxidant that helps protect the liver.
Classification
Doctors categorize drug-induced liver damage in various ways, such as by how the drug damages the liver, how liver cells are affected, and which liver enzyme abnormalities are detected by blood tests Liver Blood Tests Liver tests are blood tests that represent a noninvasive way to screen for the presence of liver disease (for example, hepatitis in donated blood) and to measure the severity and progress of... read more . For example, drugs may damage the liver by directly damaging liver cells (hepatocellular), by blocking the flow of bile out of the liver (cholestatic), or by doing both.
Symptoms of Drug-Related Liver Injury
Symptoms of liver disease Overview of Liver Disease Liver disease can manifest in many different ways. Characteristic manifestations include Jaundice (a yellowish discoloration of the skin and whites of the eyes) Cholestasis (reduction or stoppage... read more vary from the general (such as fatigue, a general feeling of being unwell, nausea, itching, and loss of appetite) to the more severe (such as jaundice, an enlarged liver, pain in the upper right part of the abdomen, confusion, disorientation, and reduced alertness).
Diagnosis of Drug-Related Liver Injury
A doctor's evaluation
Liver blood tests
After stopping the drug suspected of causing damage, doctors repeat liver tests. A significant decrease in liver enzyme levels further supports the diagnosis of drug-induced liver damage.
Liver damage caused by drugs
If liver damage caused by drugs is identified quickly, people have a better prognosis.
Doctors ask which drugs are being taken to determine whether any can cause liver damage. Doctors also do blood tests to measure levels of specific liver enzymes and to evaluate how well the liver is functioning and whether it is damaged ( liver tests Liver Blood Tests Liver tests are blood tests that represent a noninvasive way to screen for the presence of liver disease (for example, hepatitis in donated blood) and to measure the severity and progress of... read more ). Drug-induced liver injury (DILI) is likely when results of liver tests are typical of the liver damage usually caused by a drug that the person is taking. Drugs sometimes cause damage after they are stopped, even when the dose was not high, and sometimes it can take several months for DILI to improve. Thus, determining that a drug is the cause is sometimes difficult or impossible.
Liver damage from other causes
Because no test can confirm the diagnosis, doctors also check for other causes of liver damage. Blood tests to check for hepatitis Overview of Hepatitis Hepatitis is inflammation of the liver. (See also Overview of Acute Viral Hepatitis and Overview of Chronic Hepatitis.) Hepatitis is common throughout the world. Hepatitis can be Acute (short-lived) read more , autoimmune disorders, and other causes are done. Pressing on the upper abdomen to determine the size of the liver and doing imaging tests, such as ultrasonography Ultrasonography Imaging tests of the liver, gallbladder, and biliary tract include ultrasonography, radionuclide scanning, computed tomography (CT), magnetic resonance imaging (MRI), endoscopic retrograde cholangiopancreatography... read more or computed tomography Computed Tomography Imaging tests of the liver, gallbladder, and biliary tract include ultrasonography, radionuclide scanning, computed tomography (CT), magnetic resonance imaging (MRI), endoscopic retrograde cholangiopancreatography... read more (CT), can also help doctors identify other causes of liver damage.
Prevention of Drug-Related Liver Injury
When some drugs that can damage the liver (such as statins) are used, doctors sometimes regularly do blood tests to monitor liver enzyme levels. Such monitoring may detect problems early and may help prevent liver damage. For most drugs, monitoring liver enzyme levels is not done.
Treatment of Drug-Related Liver Injury
Stopping the drug
Administration of antidote if available
Sometimes corticosteroids
Sometimes liver transplantation
Usually, stopping the drug results in recovery. Drugs to relieve symptoms such as itching can be used.
Only a few drugs have antidotes. For example, acetylcysteine can be used if people have taken an overdose of acetaminophen Acetaminophen Poisoning Acetaminophen, a common ingredient in many prescription and non-prescription drugs, is safe in normal doses, but severe overdose can cause liver failure and death. People sometimes ingest too... read more . Corticosteroids may be appropriate in some cases.
If the damage is severe, people may be referred to a specialist. Liver transplantation Liver Transplantation Liver transplantation is the surgical removal of a healthy liver or sometimes a part of a liver from a living person and then its transfer into a person whose liver no longer functions. (See... read more may be required.
More Information
The following is an English-language resource that may be useful. Please note that THE MANUAL is not responsible for the content of this resource.
U.S. Food and Drug Administration: Sometimes Drugs and the Liver Don't Mix: Consumer-friendly information on how to prevent the potentially toxic effects of drug use on the liver.
