Sildenafil and tadalafil are FDA approved drugs for the treatment of male erectile dysfunction, however, the presence of these undeclared active ingredients renders the product an unapproved drug for which safety and efficacy has not been established and, therefore, subject to recall, FDA says. The product may pose a threat to consumers because these active ingredients may interact with nitrates found in some prescription drugs (such as nitroglycerin) and may lower blood pressure to dangerous levels, which can be life-threatening.