While there are concerns that these drug products may work because of their "all natural" ingredients, or because of a placebo effect, a larger threat is that these products work because of their hidden active ingredients that may be harmful.
The FDA has stated that:
"Many consumers perceive these products as completely safe because they are often sold with labeling, suggesting that they are all-natural alternatives to prescription drug products that have been approved by FDA for treating ED. But these products may be laced with potentially hazardous ingredients that aren't noted on the label" (FDA, 2009).
This is common among erectile (ED) dysfunction drugs and weight-loss supplements.
These hidden ingredients may cause adverse effects and, similarly, may adversely interact with prescription medications that individuals are already taking.
More information on drug products to avoid because of hidden ingredients:
Links to FDA warnings to consumers about hidden ingredients in drug products
Hidden Risks of Erectile Dysfunction "Treatments" Sold Online
Health Fraud Scams
FDA Warning Letters for Health Fraud