A beauty supplement with an ugly downside

FRESNO, Calif. (KFSN) -- Biotin is the beauty vitamin shown to improve hair, skin, and nails.

But experts now warn this supplement may come with an ugly downside.

Mounting research shows high doses of biotin can interfere with common, diagnostic lab tests, making it more difficult for doctors to read results.

Some say it could even lead to a misdiagnosis.

"Over the last 18 months, the number of cases that have reported biotin interference in the literature has increased dramatically," said Academy of Dermatology Dr. Dana Stern.

The FDA has also seen an increase in the number of reported adverse events, including one death, related to biotin interference, leading the agency to issue a safety alert.

Many documented cases are specific to thyroid testing. But experts warn it could also impact everything from hormone to cancer screenings

"And even things like cardiac enzymes, which can measure whether a person is having a heart attack in an acute setting," said Dr. Dana.

That is because the tests, often used contain biotin themselves and the combination can skew certain lab results falsely positive or negative.

"So far, all of the studies have shown that interference occurs at biotin doses of 10,000 micrograms and higher," said Dr. Dana.

We found several supplements marketed for hair, skin, and nails that contain 10,000 micrograms in a single daily dose.

Medical experts also point out many people don't realize they are getting biotin from other supplement sources.

It is best to consult your doctor if you're thinking of taking it.

"The consensus is that you should stop taking biotin 48 hours to one week prior to having your laboratory results," said Dr. Dana.