An analysis of data collected by the US Food and Drug Administration (FDA) between 2007 and 2016 found more than 700 over-the-counter supplements contain unlabeled pharmaceuticals that could potentially have life-threatening consequences.  

More than half of American adults say they use dietary supplements – which include vitamins, minerals, botanicals, amino acids, and enzymes not intended to treat or prevent disease – amounting to a $35 billion industry.

Under a decades-old act, supplements are classified as a type of food and do not receive the same federal regulation as drugs. However, an analysis published in the Journal of the American Medical Association identified 776 dietary supplements that contain unlabeled pharmaceuticals, 20 percent of which had more than one ingredient not approved by the FDA and nearly one-third that had received multiple warnings. In all, a total of 146 companies were implicated. Most of the products were marketed for sexual enhancement (45 percent), weight loss (40.9 percent), or muscle building (nearly 12 percent), some of which were manufactured by companies "even after the prior public FDA warnings."

“The drug ingredients have the potential to cause serious adverse health effects due to misuse, overuse, or interaction with other medications, underlying health conditions, or other pharmaceuticals within the supplement,” Corey Egel with the California Department of Public Health told IFLScience.

The most commonly found ingredients included the sexual-enhancing drug sildenafil, which has been shown to interact with nitrates found in drugs for diabetes, high blood pressure, and high cholesterol. Sibutramine for weight loss was also identified, even though it has the potential to increase blood pressure or pulse rate, especially in those with a history of heart disease or stroke. Synthetic steroids for muscle building were also found, despite their association with liver injury, hair loss, kidney damage, and heart attack.

Researchers not affiliated with the FDA analyzed data from the agency’s Center for Drug Evaluation and Research department that documents consumer complaints and dietary firm reports of adverse effects that require medical intervention to prevent death, hospitalization, or birth defects. If a supplement is deemed a health risk, then the agency can issue a class action recall; however, this is difficult to prove and often goes underreported. In fact, poison control centers received over 1,000 more reports of adverse events associated with dietary supplements than the FDA did from 2008 to 2010.

“The study lays a foundation for ongoing enforcement work in this area, by the FDA and other partner agencies, to curb the illegal manufacture, importation, distribution, and sales of adulterated dietary supplements,” said Egel.

It should be noted that the findings are limited to drugs for which the FDA tested, a number and variety that is not disclosed in the study.