“All natural” fixes for erectile dysfunction could hurt you a lot more than they could ever help, says the US Food and Drug Administration.

In a consumer update issued Oct. 2, the FDA warns men not to consume supplements or foods that promise to improve sexual performance or stimulation. They could have undisclosed drugs and other ingredients that can be dangerous to the user’s health.

In testing by the FDA, nearly 300 of these kinds of products were found to have undisclosed drug ingredients in them, including in some cases the same active ingredients found in prescription drugs like Viagria, Cialis, and Levitra. While those drugs have received approval from the FDA, the non-prescription supplements can contain dangerously high levels of the active ingredients or unapproved drug combinations. One product tested had 31 times the prescribed dosage of taladafil, the active ingredient in Cialis, plus dapoxetine, a non-FDA approved antidepressant. These products also can interact with other prescriptions the consumer already is taking.

The FDA says that they’ve seen these products sold in pill-form, in coffee, oral strips, and chewing gum, and in places like gas stations and vending machines. Reading the label isn’t necessarily going to tell you exactly what’s in the product, says Gary Coody, the FDA’s national health fraud coordinator.

Americans spend more than $20 billion on dietary supplements in the US, according to the Natural Products Foundation industry trade group, which did not immediately respond to a request for comment on the FDA warning. Unlike prescription drugs, dietary supplements don’t need FDA approval before they are sold. This lax regulation has led to numerous investigations and enforcement actions for both dangerous ingredients and mislabeled products that aren’t what they claim to be.

“Some of the ingredients in these products have chemicals that have never undergone any type of safety analysis in the United States. You just don’t know what you’re getting,” says Brad Pace, regulatory counsel at FDA’s Health Fraud Branch.

For men with erectile dysfunction, play it safe and go to the doctor.