Before you get too worried, it's worth pointing out that it's not the actual biotin that's potentially harmful -- it's the fact that it can skew blood tests (like providing false positive on pregnancy tests, or false negatives on cancer or cardiac health tests). "Biotin in patient samples can cause falsely high or falsely low results, depending on the test," explained the FDA in their statement. "Incorrect test results may lead to inappropriate patient management or misdiagnosis."
Still, the consequences can be grave: "The FDA has seen an increase in the number of reported adverse events, including one death, related to biotin interference with lab tests."
The FDA also warns that you'll want to keep a special eye out for supplements "labeled for hair, skin, and nail benefits," that "may have high levels of biotin." Notably, there are high levels of biotin in Insta-famous beauty supplements like the Kylie Jenner-promoted SugarBearHair, or Hum Nutrition, which you might recognize from the aisles of your local Sephora.
At the end of the day, the main takeaway is to be aware of biotin's ability to skew your blood tests: The FDA advises talking to your doctor if you're worried about your biotin levels, or any test results that you think might be erroneous.
Source : http://www.totalbeauty.com/content/blog/fda-biotin-warning-171130