The U.S. Food and Drug Administration is re-issuing a warning about the dangers of mercury in skin creams, beauty and antiseptic soaps, and lotions.

In the past few years, the FDA and state health officials have discovered numerous products that contain mercury, and there have been cases in which people exposed to such products have had mercury poisoning or elevated levels of mercury in their bodies. The FDA does not allow mercury in drugs or in cosmetics, except under very specific conditions where there are no other safe and effective preservatives available – conditions that these beauty products do not meet.

The FDA suggests checking the label to see if the words “mercurous chloride,” “calomel,” “mercuric,” “mercurio,” or “mercury” are listed. If the product contains these ingredients, avoid it.  The products are usually marketed as skin lighteners and anti-aging treatments. Adolescents may use these products as acne treatments.

Jason Humbert of FDA’s Office of Regulatory Affairs says these products usually are manufactured abroad and sold illegally in the United States, often in shops catering to the Latino, Asian, African, or Middle Eastern communities. They are promoted online on social media sites and sold through mobile apps. Consumers may also have bought them in another country and brought them back to the U.S. for personal use, he adds.

If the ingredients aren’t listed and there is no product label, don’t assume it’s fine, the FDA warns. Federal law requires that ingredients be listed on the label of any cosmetic or nonprescription drug.  In addition, don’t use drugs or cosmetics labeled in languages other than English unless English labeling is also provided. That’s also a sign that the product may be marketed illegally.

Sellers and distributors who market mercury-containing skin whitening or lightening creams in the U.S. may be subject to enforcement action, including seizure of products, injunctions, and, in some situations, criminal prosecution.