Harvard Medical School's Dr Pieter Cohen revealed that while almost all of the drugs contain Viagra, which is safe, they are often a combination of two or more drugs, some of which are new compounds that have never been tested for side effects.
Dr Cohen added that contrary to the claims made by the drug manufacturers, there is no evidence that such pills improve the sexual function.
"These products either do not work, or if they do work, are potentially harmful. If you want a natural sex enhancer, talk to your doctor about prescription 'yohimbe,' but it may have side effects and it's not very effective. Still, if you want to avoid Viagra, that's the way to go. When it comes to any supplement sold for sexual enhancement, it should be avoided because it's either going to be useless or potentially harmful", Dr Cohen said.