Horny Goat Weed: Research · Nutrient Desk

Why is it studied for erections?

An Italian laboratory study found that an Epimedium extract and icariin inhibited the enzyme PDE5. A chemically modified icariin derivative had activity close to sildenafil in that assay. This was an enzyme experiment, not a trial showing that the herb works like sildenafil in people. 1

Male Sexual PerformanceToo little evidence

The mechanism is a research lead; clinical benefits from Epimedium alone remain uncertain, with combination products complicating interpretation. 1 2

What happened in the bone trial?

A 24-month trial randomized 100 women 10–18 years past menopause to a flavonoid mixture or placebo; 85 completed it. Bone density was maintained with the mixture while it declined with placebo. Both groups also received calcium. The measured benefit concerned bone density, not demonstrated fracture prevention. 3

Bone densityToo little evidence

This specific mixture offers a human signal, but does not establish the same result for all horny goat weed products. 3

Effects by health goal

Open an effect to see the studies behind its rating. Bars show the size of the effect; the letter grades the evidence.