Most medicinal herbs are reasonably safe when they are used as directed, under the guidance of a qualified expert. However, people with a personal or family of liver disease must use caution when using any medicinal herb. Many can also increase the risk of severe liver damage from other products, like alcohol or acetaminophen (Tylenol).
Avoid all the following popular herbs if you have liver disease or take a medication that is metabolized by the liver. All of these medicinal herbs can harm your liver and cause serious problems like hepatitis, cirrhosis, liver failure and liver cancer.
Black cohosh is a popular herbal remedy for menopause-related discomforts, and millions of women have taken it without harm. However, a few women have developed hepatitis and other liver problems while taking the herb, and health care providers suspect that it may play a role in these diseases.No cases of liver disease have been directly linked to black cohosh, and there is not enough evidence to firmly conclude that this herb can harm the liver. Nevertheless, people with liver disease should avoid black cohosh until more studies have evaluated its safety.
The broaf-leafed herb comfrey has been used for centuries to treat broken bones, sprains, pulled muscles and arthritis. While herbalists have historically recommended comfrey as a tea or capsule, it is no longer considered to be safe for internal use. Comfrey contains pyrrolizidine alkaloids (PAs)– toxic compounds that can cause hepatitis, fibrosis, cirrhosis and terminal liver failure. Comfrey ointments are safer than oral comfrey preparations, but people with liver disease should avoid comfrey entirely.
Several studies have shown that butterbur outperforms several pharmaceutical treatments for hay fever and seasonal allergies. Unfortunately, unprocessed butterbur contains pyrrolizidine alkaloids similar to those found in comfrey. Several manufacturers offer “PA-free” butterbur supplements, which have been processed to remove all compounds that may harm the liver. People with liver disease can safely use PA-free butterbur under the guidance of a health care provider, but unprocessed butterbur is not safe for internal use.
In very low doses, this member of the mint family may be safe for occasional use. However, pennyroyal tea and pennyroyal oil have both caused terminal liver failure in women who have used it to induce menstruation. In addition to causing significant liver damage, pennyroyal is toxic to the heart, kidneys and central nervous system.
Kava-kava is a highly effective treatment for anxiety and may be more effective than some pharmaceutical interventions. Compounds in kava supplements may cause liver problems like hepatitis, cirrhosis and liver failure. Most cases of kava-related liver problems have involved ethanol-based extracts instead of traditional water-based formulas, but people with liver disease should avoid all forms of the herb. Do not take kava with other products that are metabolized by the liver.
Links and Resources:
University of Maryland Medical Center: Comfrey
Mayo Clinic: Hay Fever- Alternative Medicine
National Institutes of Health: Pennyroyal
National Institutes of Health: Black Cohosh
National Institutes of Health: Kava