Herbal and dietary supplements are a booming business in the United States—more than half of all adults report taking them. But using supplements can be risky for people with liver disease.

Some dietary supplements can be helpful, especially for individuals with a vitamin or mineral deficiency. But many others are not backed by scientific evidence, and some can actually be harmful. An estimated 20 percent of liver injury cases in the United States are related to supplement use. In the worst cases, they can lead to liver failure, the need for a liver transplant or death.

Some supplements, such as performance-enhancing anabolic steroids, are known to harm the liver. Commercial products may contain a mix of ingredients that are not clearly stated on their labels. And unlike pharmaceuticals, supplements are not strictly regulated by the Food and Drug Administration.

People living with hepatitis C, especially those with cirrhosis, should be particularly careful about using herbs and supplements. Be alert for signs of liver injury, such as unusual fatigue, abdominal pain, jaundice (yellow skin and eyes) and dark urine. Tell your doctor what you’re taking—or better yet, ask before trying!