What is gakjaja (jogakja)?

Gakjaja, also called jogakja, is the dried thorn of the Chinese honey locust tree. Its Latin name is Gleditsia sinensis, and in English it is called honeylocust thorn. In Korean herbal practice it is used for boils, abscesses and skin sores that hold pus.

It is a single herb, but it is almost never used alone. A Korean herbalist adds a small amount to a mixed formula, most often a boiled herb tea. It is also used as a wash for the skin.

The short answer on proof: we could find no human trials of gakjaja on its own. Its standing comes from long use, and long use is not proof that a herb works. That point is made here once and is not repeated in each section below.

How does gakjaja (jogakja) work?

No one has shown how gakjaja works in the body. There is no human study that tracks what it does once you take it.

In old Korean and Chinese texts, the thorn is said to "push out pus" and open a sore that will not drain. The shape of the thorn was part of the thinking. Herbs that pierce were matched to problems that needed piercing.

Lab work gives a partial modern picture. Extracts of the plant have slowed the growth of some bacteria and fungi in a dish. Some lab tests also show effects on swelling and on cancer cells grown in a dish.

Work in a dish or in mice does not tell you what happens in a person. Doses in lab work are often far higher than a person would take. So treat any talk of how it works as an idea, not a fact.

What forms does gakjaja (jogakja) come in?

Gakjaja comes in a few plain forms:

Dried whole or sliced thorns, boiled with other herbs into a tea. This is the most common form in Korea.

Powder, mixed into pills or granules by a herb shop or maker.

A cooled, strained brew used as a skin wash or soak.

It also turns up inside ready-made Korean and Chinese herb formulas, where the label may list it as jogakja, zao jiao ci or Gleditsiae Spina. Check labels if you have been told to avoid it.

Where it comes from:

Gakjaja belongs to East Asian herbal medicine. Korean texts group it with herbs that drain pus and open stuck sores. The Dongui Bogam, a Korean medical book from 1613, is one of the works that names it.

Chinese herb books list the same thorn as zao jiao ci and use it in much the same way. Healers have used it this way for many hundreds of years.

Its place rests on that written record and on daily use by trained herbalists. No modern trial has tested it in people.

What does gakjaja (jogakja) help with?

• Boils and skin abscesses: This is the main traditional use, and it is a strong one in the written record. Korean formulas add gakjaja to help a boil come to a head and drain. No human trial has tested it for this. A boil that grows, throbs or comes with a fever needs a doctor, not a herb.
• Sores that will not drain: Old texts describe gakjaja as the herb for a sore that is stuck and will not open. It was paired with herbs that clear heat. There is no trial evidence for this use. Lab work showing action against some bacteria does not prove it helps a real sore.
• Breast abscess (a pocket of pus in the breast): Classical formulas list gakjaja for a hot, painful, swollen breast with pus. This use appears in both Korean and Chinese texts. No human trial supports it. This problem needs medical care, and many women with it are breastfeeding, when this herb should be avoided.
• Hard, swollen lumps under the skin: Tradition uses gakjaja to soften and open hard lumps that sit under the skin. It was seen as a herb that breaks through blockage. No human study has tested this. Any new or growing lump should be checked by a doctor first, since some lumps are serious.
• Long-lasting skin sores and ulcers: A cooled brew was used as a wash for sores that heal slowly. This is a folk use with a long record in Korea. We found no trial of this wash in people. Slow-healing sores can be a sign of diabetes or poor blood flow and should be seen by a doctor.

Which foods are rich in gakjaja (jogakja)?

Honey locust pods and seeds are sometimes called edible. Do not treat them as food; raw pods and seeds of this tree can poison you.

What are the side effects of gakjaja (jogakja)?

• Nausea and stomach ache
• Vomiting
• Loose stools or diarrhoea
• A scratchy or burning throat
• Skin rash or itching from an allergy
• Breakdown of red blood cells at high doses, which can cause pale skin, dark urine and great tiredness

Good to know:

Most reported trouble is stomach upset, and it usually settles when the herb is stopped. Nobody has counted how often this happens, because there are no trials.

The serious risk sits with saponins, the soap-like chemicals in the plant. In large amounts, saponins can damage red blood cells. This is mainly a risk with the pods and seeds, or with far too much of the thorn.

Stop taking it and get medical help if you get dark urine, yellow skin or eyes, great tiredness, a spreading rash, or trouble breathing.

How much gakjaja (jogakja) should you take?

• Recommended daily: No safe daily dose has been set by human trials, because no trials exist. In Korean and Chinese practice, about 3 to 9 grams of the dried thorn a day is boiled with other herbs into a tea. It is a small part of a larger formula, never the whole of it. Do not work out a dose yourself. Get the amount, and the rest of the formula, from a licensed Korean medicine doctor (hanuisa) or another trained herbalist. Never swallow raw pods or seeds from a honey locust tree. They are a different part of the plant, they are stronger, and they can poison you.
• Best time of day: Usually split into two or three doses across the day, as part of the formula it came in. There is no evidence that one time of day works better than another.
• With or without food: Take it with food or just after a meal. The saponins (soap-like plant chemicals) in it can upset an empty stomach.
• Time to effect: Unknown. No trial has measured it. Traditional use expects a change in a skin sore within a few days, so if nothing has changed in 2 to 3 days, see a doctor.
• How long to take it: Short courses only. Traditional use is measured in days to a few weeks, not months. If a boil or sore is no better in 2 to 3 days, stop and see a doctor. Skin infections can spread fast. Anyone using it for more than about two weeks should be rechecked by the herbalist who prescribed it.