Educational information, not medical advice — ask your doctor or midwife.
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Eumyanggwak is a dried herb used in Korean medicine. It is the leaf of the plant Epimedium koreanum. In English it is sold as Korean epimedium, or horny goat weed.
It is a single herb, not a blend. Korean and Chinese texts group it with herbs for low sex drive, weak knees and sore joints. Most shops today sell it in pills and powders aimed at energy, sex drive and bone health.
The honest verdict on proof is short. Lab and animal work looks busy, but good human trials on this plant are very few. A long past of use is not proof that a herb works, and that gap matters here.
This herb is not a mild food-type plant. Reports link products made from Epimedium to liver harm, a fast heartbeat and more bleeding. Read the safety part below before you try it.
No one can say for sure how it works in people. The lab story is clearer than the human one.
The main plant chemical is icariin. In test tubes and in rats, icariin blocks an enzyme called PDE5 (a body chemical that controls blood flow in the penis). That is the same target that the drug Viagra hits, but the plant is far weaker and far less exact.
Icariin also acts a little like estrogen (a female sex hormone) in lab cells. Animal work suggests it may slow bone loss and may help blood vessels relax. None of this has been shown to hold true in good human trials.
Treat the above as a lead, not a fact. A plant that works in a dish often does nothing in a person.
You may meet it in these forms:
Dried sliced leaf, boiled into a strong tea (a decoction).
Raw powder, loose or packed into capsules.
Extract capsules and tablets, often labelled by icariin percent.
Tinctures and herbal wines, where the leaf is soaked in alcohol.
Leaf fried in lamb fat, a classic Korean and Chinese prep step.
As one herb inside a larger formula written by a trained practitioner.
The herb has a long past across East Asia. Chinese texts list it as yin yang huo, going back to the Shennong Bencao Jing, an early herb classic.
In Korea it appears as eumyanggwak in the Donguibogam, the great Korean medical work of 1613. Japanese Kampo uses it too.
Old texts place it in the group of herbs said to warm the kidney and lift yang energy. Those are tradition terms, not lab findings.
Stop the herb and get medical help the same day if your skin or the whites of your eyes turn yellow, your urine goes dark, or you have pain under your right ribs. These can be signs of liver harm.
Call emergency services for chest pain, fainting, a racing heartbeat that will not settle, bleeding you cannot stop, or swelling of the face, lips or throat. An erection lasting more than four hours is also an emergency.
Book a normal appointment if you get a rash, ongoing dizziness, changes in your periods, or new breast tenderness. Also see your doctor rather than self-treating if erection trouble, deep tiredness or bone pain is new, since these can point to a problem worth finding early.
Evidence grades and traditional-use labels are explained in our methodology. Nothing here is medical advice.
Reviewed by the HealisticMD editorial team How we grade evidence →
The published evidence for Eumyanggwak is weak or absent. That usually means no controlled trial has tested it, not that a trial found it ineffective — the two are different, and we grade only what has been published.
What it is typically used for, usual dose, cautions, and the study behind it where real trial data exists.
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