Horny Goat Weed

Epimedium · Epimedium brevicornum · Yin yang huo

Snapshot

Indications	Contraindications
Primary osteoporosis^{1, 2} Postmenopausal bone loss³ Sexual function⁴ Fatigue⁵	Heart disease⁵ Hormone-sensitive cancers⁵ Aromatase inhibitor use⁵ Hypersensitivity to Epimedium⁵

Horny goat weed (Epimedium) is the leaf of Epimedium plants, used in traditional Chinese medicine for fatigue and sexual problems⁵. Its main flavonoid, icariin, shows mild phosphodiesterase-5 inhibition and estrogen-related activity⁵. It is studied for bone loss in postmenopausal women, taken for libido and erectile function in men, and used for fatigue, which has not been tested in clinical trials⁵.

Meta-analyses of randomized controlled trials in primary osteoporosis found improved bone density with Epimedium as an adjunct or alternative to conventional therapy^{1, 2}. A review of total flavonoids found only a small lumbar spine difference of doubtful clinical significance⁶. For sexual function, reviews describe low-quality human evidence and no definitive effect on erectile dysfunction^{4, 7}. In a 2020 neuronal cell study, icariin reduced sodium azide-induced damage and tau phosphorylation; no human trial has tested this. Many supplement products list horny goat weed, mostly as capsules; see Form comparison.

Memorial Sloan Kettering lists heart disease as a contraindication after a case of rapid irregular heartbeat in a patient with heart failure⁵. Per that source, possible interactions with aromatase inhibitors and cytochrome P450 3A4 substrates are of unknown clinical relevance, and patients are asked to consult and be monitored by a physician⁵.

Last updated October 16, 2026. Read how we make monographs.

In the full monograph

56 sources, 41 studies

When to useThe situations practitioners use it for, each with the reason and the study behind it.
SafetyWho should avoid it, who needs extra care, and the side effects reported in studies.
InteractionsThe medicines and supplements it interacts with, the effect of each, and what labeling says to watch.
Protocol notesThe doses used in studies, how and when they were taken, and how the forms on the market compare.
How it worksWhat it is and how it works in the body, in plain terms.
Published studiesThe studies behind each use, popular claims checked against them, and trials still under way.
Word of mouthWhat patients and practitioners report online, kept separate from the clinical evidence.
Clinical perspectiveA closing read of where the evidence is solid, where it is thin, and what has not been studied.

Snapshot

In the full monograph

Sources