What is Agyo?

Agyo is a hard, dark, glue-like gelatin made by simmering donkey hide (Latin name Equus asinus) for a long time. It is also sold as donkey-hide gelatin or by its Chinese name, ejiao. It is a single-substance remedy, not a mixed formula.

In Korean traditional medicine it is used as a blood and yin tonic. That means it is given to people described as tired, pale, light-headed, dry or prone to bleeding. Common traditional targets are heavy menstrual bleeding, nosebleeds, a dry hacking cough, dry skin and restless sleep.

Here is the honest verdict up front. Agyo has deep, well-documented traditional standing across East Asia, but we could not find reliable human trials showing that it treats any of these problems. Long traditional use is not proof of effect, and that point is not repeated later in this document.

How does Agyo work?

Nobody has shown clearly how Agyo works in the body, and the traditional explanation and the chemical one do not match up.

In traditional terms, Agyo is said to "nourish blood" and "moisten dryness", which is a way of describing a pattern of symptoms rather than a measured effect on cells.

In chemical terms, it is mostly collagen, an animal protein. Once you eat it, your gut breaks collagen into ordinary amino acids, the same building blocks you get from any protein food. Laboratory and animal studies suggest collagen peptides may nudge blood-cell production, but that has not been confirmed in people.

What forms does Agyo come in?

The classic form is a solid block or bar of dark amber gelatin, which is broken up and dissolved in hot water, warm rice wine or porridge. Modern shops also sell granules, powder, softgel capsules and ready-made drink sachets.

A very common Korean and Chinese preparation is a cake made of Agyo mixed with walnuts, black sesame, goji berries and rock sugar. It is eaten in small slices as a food-like tonic.

Dissolving the raw block takes patience, because the gelatin softens slowly. No form has been shown in trials to work better than another.

Where it comes from:

Donkey-hide gelatin appears in Chinese medical writing as early as the Han dynasty, roughly 2,000 years ago, and the most famous source was the town of Dong'e in Shandong.

It entered Korean practice through classical medical texts and is listed in the Donguibogam, the Korean medical compendium completed in 1613. It has been a standard blood tonic in Korean, Chinese and Japanese Kampo practice ever since.

It has always been expensive, and demand has put real pressure on donkey populations worldwide. Fakes and substituted hides are common, which matters for both ethics and safety.

What does Agyo help with?

• Tiredness and pallor linked to low blood counts (anaemia): This is the best-known traditional use of Agyo, and it is a classical one across East Asia. The supporting research is mostly laboratory and animal work on blood-cell production. We could not identify well-designed human trials showing that Agyo raises haemoglobin (the oxygen-carrying protein in red blood cells). Anaemia has many causes, some of them serious, so it needs a blood test rather than a tonic.
• Heavy or prolonged menstrual bleeding: Traditionally, Agyo is a first-choice remedy for bleeding that is thought to come from "blood deficiency". It is often combined with other herbs rather than used alone. Human evidence for this use is not available in any form we can point to. Heavy bleeding that soaks through pads, lasts more than a week or leaves you dizzy should be checked by a doctor.
• Nosebleeds and other minor bleeding: Classical texts describe Agyo as a remedy that helps "hold blood in the vessels". This is a traditional description, not a measured clotting effect. No human trial evidence supports it. If you bruise or bleed easily without an obvious reason, that needs medical assessment.
• Dry cough with little phlegm: Agyo is a standard ingredient in traditional formulas for a dry, tickly, unproductive cough, where it is described as moistening the lungs. There is no human trial evidence for this use. A cough lasting more than three weeks, or one that brings up blood, needs a doctor.
• Restless sleep and night-time agitation: Some classical formulas use Agyo for people who feel hot, dry and restless at night and sleep poorly. Evidence in people is absent. Nothing suggests Agyo works as a sedative in the way a sleeping tablet does.
• Dry skin and brittle hair: This is a modern marketing use built on the fact that Agyo is collagen. Trials of collagen peptides from other animals have looked at skin hydration, but those products are not Agyo and the results do not transfer. No trials of Agyo itself for skin or hair could be identified.
• Bleeding in pregnancy (traditional use only): Classical Korean and Chinese practice used Agyo for bleeding and threatened miscarriage in pregnancy, under a practitioner's supervision. We list this because it is part of the traditional record, not because it is supported. Bleeding in pregnancy is an urgent medical matter. Do not self-treat it, and see the section on who should avoid Agyo.

Which foods are rich in Agyo?

1. Bone broth: contains similar collagen peptides, though from cattle, pigs or chicken rather than donkey
2. Jokbal (braised pig trotters): a traditional Korean dish rich in animal collagen
3. Gelatin desserts and jellies: made from the same kind of animal collagen
4. Dojeon-style gelatin cakes made with walnut, sesame and goji: the usual ready-made way Agyo itself is eaten

Practical Tips:

No ordinary food contains Agyo itself; these simply supply similar animal collagen.

What are the side effects of Agyo?

• Bloating and a heavy, full feeling after eating
• Nausea
• Loss of appetite
• Loose stools or, in some people, constipation
• Greasy or cloying taste that puts people off food
• Allergic reaction in people sensitive to gelatin or animal proteins
• Rash or itching
• Harm from contaminated or faked products, including heavy metals such as lead

Good to know:

Most reported problems are digestive and mild, and they usually settle when you stop.

The bigger concern is product quality rather than the gelatin itself. Testing in several countries has found donkey-hide gelatin faked with pig, cattle or horse hide, and some samples have carried heavy-metal contamination. That is why this page is rated at a caution level.

Stop taking it and get medical advice if you develop a rash, swelling of the face or lips, or trouble breathing.

How much Agyo should you take?

• Recommended daily: No dose has been established by human trials, so any figure comes from tradition rather than testing. Traditional Korean and Chinese practice uses roughly 3 to 9 grams a day of the gelatin, dissolved in hot water, warm rice wine or porridge. Ready-made cakes and sachets usually supply a similar amount per serving. Start at the low end. Use the maker's label if it gives less, and check with a Korean medicine practitioner or your doctor before starting.
• Best time of day: Usually taken once or twice a day, in the morning and early evening. Some traditional advice puts it before bed for people who sleep badly. Timing has never been tested.
• With or without food: Take it with or just after food. Agyo is rich and sticky, and taking it on an empty stomach makes nausea and bloating more likely.
• Time to effect: Tradition describes a slow tonic effect over two to six weeks. Because no trials exist, no honest timeline can be given.
• How long to take it: Traditional courses run for a few weeks to a couple of months, often timed around the menstrual cycle or the colder months. Reassess after about four weeks. If nothing has changed, stop rather than pushing on, and get the underlying problem looked at properly.