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What Is Icariin in Horny Goat Weed, and What Is Known?
Icariin is the main compound studied in horny goat weed (Epimedium). In lab work it shows a mild PDE5-inhibiting effect, but Memorial Sloan Kettering calls the human evidence limited. HoneyBoost prints 10 mg of an 8:1 horny goat weed extract and does not print its icariin content.
Written by the HoneyBoost label deskUpdated · 5 min read
The compound01
What is icariin?
Icariin is a plant compound found in Epimedium species, sold as horny goat weed or yin yang huo. It is the compound most often named when people explain why the herb is studied.
Memorial Sloan Kettering notes that icariin can show "a mild phosphodiesterase-5 inhibition effect" (MSK, Epimedium (Horny Goat Weed)). PDE5 is the enzyme that prescription ED drugs act on. A mild effect in a lab is a long way from a result in a man.
That is why we never write that horny goat weed works like a prescription ED drug. No human erection trial of Epimedium turned up in the sources we read.
Lab vs people02
Does icariin work in humans?
We cannot say it does. MSK states that scientific evidence for Epimedium is limited and that more studies are needed to verify effects on sexual dysfunction (MSK, Epimedium (Horny Goat Weed)). Fatigue has not been studied in clinical trials.
Lab, cell and animal findings tell researchers where to look. They do not show what a swallowed dose does in a person, at what amount, or for how long.
| Question | What the sources say |
|---|---|
| Lab effect of icariin | A mild PDE5-inhibiting effect |
| Human erection trial | None found in our sources |
| Sexual dysfunction | "More studies are needed" |
| Fatigue | Not studied in clinical trials |
| Safety evaluations | Lacking, per MSK |
The label03
How much icariin is in a HoneyBoost gummy?
The label does not say. It prints "Horny Goat Weed (Epimedium spp.) Extract 8:1, 10 mg," equal to 80 mg of the plant, and gives no icariin percentage.
An 8:1 ratio means about 8 parts of plant went into 1 part of extract. It describes how the extract was made, not how much icariin it holds. Two 8:1 extracts can contain different amounts.
The ten milligrams make up under a quarter of one percent of the gummy's 4.2 g. For more on how ratios work, see our horny goat weed dosage post. The full panel is on our Supplement Facts page.
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See packsCautions04
Who should ask a doctor before taking horny goat weed?
Anyone with heart disease or a hormone-sensitive cancer should ask first. MSK says Epimedium "should be avoided" in those groups, and lists rapid irregular heartbeat as a reported side effect (MSK, Epimedium (Horny Goat Weed)).
- Heart disease, or any fast or irregular heartbeat
- Hormone-sensitive cancers, or aromatase inhibitor medicine
- Medicines broken down by the CYP3A4 pathway (relevance unknown)
The liver picture is milder. LiverTox rates horny goat weed an unlikely cause of clinically apparent liver injury, score E (LiverTox, Horny Goat Weed).
Keep taking prescribed medicine, and ask your doctor or pharmacist about interactions. The label also says not to use it with a medical condition or other medications without a physician's advice.
Erection problems can signal heart disease, so see a clinician. Our ED basics page lists the common causes.
FAQ05
Horny goat weed icariin questions
Is icariin the same as a prescription ED drug?
No. Icariin is a plant compound, and in lab work it shows a mild PDE5-inhibiting effect. Prescription ED drugs are tested, dosed and approved medicines. A lab effect does not make horny goat weed one of them.
What is yin yang huo?
Yin yang huo is a traditional name for Epimedium plants, also called horny goat weed. MSK says it was used traditionally for fatigue and sexual problems, and that evidence for those uses is limited.
Does the HoneyBoost label list icariin?
No. The label lists the extract amount and ratio only, 10 mg at 8:1. It prints no icariin percentage, so the amount of icariin in a gummy is unknown from the bottle.
Can horny goat weed hurt your heart?
MSK says people with heart disease should avoid it and lists rapid irregular heartbeat among reported effects. It describes one case in a man with heart failure. Ask a clinician if you have any heart condition.
Who wrote this06
Written and reviewed by
Pages built from the label, the order page and linked NIH, FDA, FTC, Mayo Clinic and peer-reviewed sources.
Last updated . Read our editorial standards and how we check reviews. This website is the information site for a USA Authorized HoneyBoost Retailer. It is not the manufacturer or the distributor named on the label. We earn money when you buy through our order links.
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