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Effects of Drugs on the Liver

by Steven K. Herrine, MD

Many drugs can affect the way the liver functions, damage it, or do both.

Some drugs, such as statins (used to treat high cholesterol levels), can increase the levels of liver enzymes and cause liver damage (usually minor) but no symptoms.

A very few drugs damage the liver enough to cause symptoms, such as jaundice, 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 drugs, whether it results in symptoms or not. The term also includes damage caused by medicinal herbs, plants, and nutritional supplements.

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) is one of the most common causes of the sudden appearance of jaundice, liver failure, 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.

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 make-up that makes people more susceptible to a drug's effects

Drinking alcohol increases the risk of liver damage because alcohol damages the liver 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. For example, drugs may damage the liver by directly damaging liver cells, by blocking the flow of bile out of the liver, or by doing both.

Drugs That Can Damage the Liver

Type of Drug

Examples

Antibiotics

Amoxicillin/clavulanate

Clindamycin

Erythromycin

Nitrofurantoin

Rifampin

Sulfonamides

Tetracyclines

Trimethoprim/sulfamethoxazole

Drugs used to treat tuberculosis (isoniazid and pyrazinamide)

Anticonvulsants

Carbamazepine

Phenobarbital

Phenytoin

Valproate

Antidepressants

Bupropion

Fluoxetine

Mirtazapine

Paroxetine

Sertraline

Trazodone

Tricyclic antidepressants such as amitriptyline

Antifungal drugs

Ketoconazole

Terbinafine

Antihypertensive drugs (used to treat high blood pressure or sometimes kidney or heart disorders)

Captopril

Enalapril

Irbesartan

Lisinopril

Losartan

Verapamil

Antipsychotic drugs

Phenothiazines such as chlorpromazine

Risperidone

Heart drugs

Amiodarone

Clopidogrel

Hormones and related drugs

Anabolic steroids

Birth control pills (oral contraceptives)

Estrogens

Pain relievers

Acetaminophen

NSAIDs

Other drugs

Acarbose (used to treat diabetes)

Allopurinol (used to treat gout)

ART drugs (used to treat HIV infection)

Baclofen (a muscle relaxant)

Cyproheptadine (an antihistamine)

Azathioprine (used to prevent rejection of an organ transplant)

Methotrexate (used to treat cancer)

Omeprazole (used to treat gastroesophageal reflux)

Statins (used to treat high cholesterol levels)

Medicinal herbs

Germander

Green tea extract

Kava

ART = antiretroviral therapy.

Symptoms

Symptoms vary from general symptoms (such as fatigue, a general feeling of being unwell, nausea, itching, and loss of appetite) to more severe symptoms (such as jaundice, an enlarged liver, pain in the upper right part of the abdomen, confusion, disorientation, and reduced alertness—see Overview of Liver Disease).

Diagnosis

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 function tests). Drug-induced liver damage is likely when results of liver function 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. Thus, determining that a drug is the cause is sometimes difficult or impossible.

Because no test can confirm the diagnosis, doctors also check for other causes of liver damage. Blood tests to check for hepatitis, 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 or computed tomography (CT), can also help doctors identify other causes of liver damage.

After stopping the drug suspected of causing damage, doctors repeat liver function tests. A significant decrease liver enzyme levels further supports the diagnosis of drug-induced liver damage.

Prevention

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 does not help.

Treatment

Usually, stopping the drug results in recovery. Drugs to relieve symptoms such as itching can be used.

If the damage is severe, people may be referred to a specialist. Liver transplantation may be required.

Only a few drugs have antidotes. For example, acetylcysteine can be used if people have taken an overdose of acetaminophen.

Resources In This Article

Drugs Mentioned In This Article

  • Generic Name
    Select Brand Names
  • TYLENOL
  • CLEOCIN
  • PAXIL
  • CORDARONE
  • PRECOSE
  • LAMISIL
  • FURADANTIN, MACROBID, MACRODANTIN
  • REMERON
  • LIORESAL
  • OLEPTRO
  • ZYLOPRIM
  • No US brand name
  • RIFADIN, RIMACTANE
  • COZAAR
  • ZOLOFT
  • ERY-TAB, ERYTHROCIN
  • PRINIVIL, ZESTRIL
  • CALAN
  • LANIAZID
  • TEGRETOL
  • PROZAC, SARAFEM
  • PRILOSEC
  • OTREXUP
  • WELLBUTRIN, ZYBAN
  • RISPERDAL
  • PLAVIX
  • AVAPRO
  • DILANTIN
  • IMURAN
  • CAPOTEN
  • VASOTEC
  • NIZORAL
  • AMOXIL
  • ACETADOTE