Know2eat

Horny goat weed

Epimedium grandiflorum

Herbs & Botanicals

What horny goat weed may help with

Ranked by how strong the human evidence is — best supported first.

Best supportedBone mineral densityLimited evidence· 1 source

Then, in order

About Horny goat weed

A leaf extract from Epimedium species used in Traditional Chinese Medicine, standardised to the flavonoid icariin. Several Epimedium species are used interchangeably.

Icariin inhibits phosphodiesterase type 5 in laboratory work — the same enzyme sildenafil targets — but at potencies orders of magnitude weaker, which makes a meaningful effect from a capsule unlikely. Human trials of the herb for sexual function are essentially absent. What does exist is a set of Chinese trials of purified epimedium flavonoids for bone density in postmenopausal women, which is a different preparation from what is sold for libido.

Sold as
Leaf extract capsule, Icariin-standardised extract, Powder, Tea, Male-performance blends
Standardised to
Commonly 10–60% icariin — a product without this marker may not resemble what was studied.
Also known as
Epimedium, Yin yang huo, Icariin, Barrenwort

What the research used

The amounts, forms and durations published trials of Horny goat weed actually administered.

These are the amounts published trials administered — not a recommendation, and not a dose to copy. Trial participants were screened, supervised and given a characterised preparation. What is in a retail bottle is frequently not what was studied, and the amount that suits one person is not general advice.

  • Studied for Bone density in postmenopausal women

    60 mg

    Limited

    Purified epimedium flavonoids, daily · 24 months

    From Chinese trials of a purified flavonoid preparation combined with other compounds, not the crude extract sold for sexual performance.

  • Studied for Sexual function

    500–1000 mg

    Not enough

    Leaf extract capsule

    Trial dosing is not established for this use. Retail amounts have no controlled human evidence behind them, and icariin content varies widely.

This is general information about food, not medical advice. It cannot diagnose, treat or replace guidance from a clinician who knows your history.

When it was taken

Each window says whether a trial compared it against an alternative, or whether it is convention and pharmacology. Most timing advice is the second kind.

None of the timings below were directly compared in a trial. They reflect how the research happened to dose, or what the pharmacology implies — which is not the same as a timing being better.

  • Any time

    Not enough

    No timing has been studied in humans for either use.

    Timing was not directly compared. This reflects convention or how the compound behaves in the body, not a trial showing this window works better.

The evidence in depth

Best supported: Limited

What each association actually rests on, and the papers behind it. A rating describes the state of the research, not how promising the supplement sounds. How we rate evidence.

Bone mineral density

Bone Health
Limited evidence

Some Chinese trials of purified epimedium flavonoids report preserved bone mineral density in postmenopausal women over two years. The preparation is not what is sold as horny goat weed, and independent replication outside China is lacking.

Limited evidence. Early human work, or mostly lab and animal research.

View the 1 source

Deep research mode adds each paper’s own conclusion and stated limitations.

Endothelial function

Circulation
Not enough evidence

There is not enough human research to say epimedium affects erectile or vascular function. The phosphodiesterase inhibition seen in cell studies is far weaker than that of prescription drugs and has not been shown to translate.

Not enough evidence. Not enough human research to say anything useful yet.

View the 2 sources

Deep research mode adds each paper’s own conclusion and stated limitations.

Things to know

Interactions, contraindications and dose limits, most serious first. Concentrated extracts interact with medication in ways the whole plant does not, so this section carries more weight here than it does on a food page.

  • Worth knowing

    Adulteration with sildenafil analogues

    Male-performance supplements are the most frequently adulterated category in regulatory testing, with undeclared sildenafil and tadalafil analogues repeatedly found. Combined with nitrates for angina, those cause dangerous drops in blood pressure.

  • Worth knowing

    Severe tachyarrhythmia case report

    A case of life-threatening rapid heart rhythm has been reported with epimedium use, and its cardiovascular effects are poorly characterised.

  • Avoid

    Pregnancy

    Epimedium should not be used in pregnancy or breastfeeding; safety data are absent and hormonal activity is plausible.

  • Interaction

    Blood pressure, anticoagulants and drug metabolism

    Interacts withAntihypertensives, nitrates, warfarin, CYP3A4 substrates

    Possible hypotension, effects on platelets and inhibition of CYP enzymes mean caution with antihypertensives, anticoagulants and narrow-margin medicines.

  • Worth knowing

    Hormone-sensitive conditions and imported sourcing

    Icariin has oestrogen-like activity in laboratory work, so it is avoided in hormone-sensitive cancers. Imported Chinese herbal products also carry documented heavy-metal contamination risk.

Evidence ratings on this page: 1 limited evidence, 1 not enough evidence.

Supplements are sold in the US without pre-market review of efficacy or safety. Nothing on this page is a recommendation to take Horny goat weed, or a dose to follow.