Some doctors warn that some popular diet pills could be dangerous. Over-the-counter diet pills known as the "Brazilian pills," claim to be all-natural, but lab tests have found that some variations of them contain illegal amphetamines, NBC 6's Jaylene Rodriguez reported.

At least four unsuspecting women taking the diet pills failed pre-employment drug tests at Baptist Health South Florida, Rodriguez reported.

Thomas Moore, the corporate director of employment health services at Baptist Health South Florida, said the women were very surprised.

Find out why the Brazilian diet pill is considered dangerous at http://www.click2houston.com/health/5096403/detail.html.