A systematic review and evidence-based analysis of ingredients in popular male testosterone and erectile dysfunction supplements.

The objective was to study available evidence for ingredients of popular over-the-counter testosterone and erectile dysfunction (ED) supplements. The top 16 male testosterone and 16 ED supplements in the USA were identified from the most popular online retailers: A1 Supplements, Amazon, Vitamin Shoppe, and Walmart. In total, 37 ingredients were identified and PUBMED online database was reviewed for randomized-controlled trials (RCT) studying their efficacy. Ingredients were categorized based on evidence quantity using an adapted version of the American Heart Association scoring system. In total, 16 ingredients from testosterone supplements and 21 from ED supplements were identified. Tribulus, Eurycoma longifolia, Zinc, L-arginine, Aspartate, Horny goat weed, and Yohimbine were most common. In all, 105 RCTs studying the identified ingredients were found. No whole supplement products have published RCT evidence. 19% of ingredients received an A grade for strong positive evidence with net positive evidence in two or more RCTs. In total, 68% received C or D grades for contradicting, negative, or lacking evidence. Overall, 69% of ingredients in testosterone supplements and 52% of ingredients in ED supplements have published RCT evidence. Many male supplements claim to improve testosterone or ED parameters; however, there is limited evidence, which should be considered when counseling patients.