What is Di Er Cao?

Di Er Cao is a small herb with yellow flowers. Its Latin name is Hypericum japonicum. In Chinese medicine it is used on its own, not in a blend.

People use it mainly for jaundice (yellow skin and eyes). It is also used for liver complaints, sores, and insect or snake bites. The whole dried plant is boiled into a tea-like drink.

Other names for it are Japanese St. John's wort and field hypericum. In China it is called Tian Ji Huang.

It is a close relative of St. John's wort (Hypericum perforatum). But it is not the same plant. Do not swap one for the other.

St. John's wort is well known for clashing with drugs. Because the two plants are related, that risk is a real concern here. No one has properly tested those drug clashes in Di Er Cao.

The evidence verdict is simple. Di Er Cao has a long record in Chinese practice. But good human trials are lacking, so its benefits in people are unproven.

Long use tells you that people valued a plant. It does not prove the plant works. That holds true for everything on this page.

How does Di Er Cao work?

No one has shown clearly how Di Er Cao works in people. Lab and animal studies are the main source of ideas about it.

In traditional terms, it is said to clear "damp-heat" and cool toxic heat. Healers linked this to jaundice, hot swellings and infected sores. That is a traditional idea, not a proven body process.

In test tubes and in animals, extracts have shown a few effects. They mop up unstable molecules, an action called antioxidant activity. They also show some action against bacteria and viruses.

Extracts have also shielded liver cells from harm by chemicals. None of this has been confirmed in human trials. Effects in a dish often do not carry over into people.

What forms does Di Er Cao come in?

Di Er Cao is most often sold as the dried whole herb, cut and sifted. You boil it into a decoction (a strong tea made by simmering).

Other forms you may meet:

Granules or powdered extract that dissolve in hot water.

Capsules or tablets of dried extract.

One part of a multi-herb Chinese formula. The amount of Di Er Cao is often not stated.

In parts of southern China, people crush the fresh plant. They put it on the skin for bites and sores.

Quality control varies widely. Herbs brought in outside regulated channels have at times held contaminants (unwanted substances).

Where it comes from:

Di Er Cao has been used in China for centuries. It is used in both folk and formal medicine. It grows in damp fields and along paths in the south of the country.

Chinese herb texts list it as a cooling herb that clears toxins (poisons). They name it for jaundice, hot painful swellings, sore throat and snakebite. Similar folk use is on record in Japan, Korea, and parts of Southeast Asia and India.

It is a known staple of Chinese herbal practice. It is not a herb shared across many unrelated traditions.

What does Di Er Cao help with?

• Jaundice and hepatitis (traditional use): This is the best-known traditional use. Chinese practitioners have given Di Er Cao decoctions for yellow skin and eyes linked to liver inflammation for generations. Human evidence is weak. Reports of use in Chinese hospitals exist but are mostly small, old and not designed well enough to show whether the herb itself helped. Jaundice and hepatitis need a doctor's diagnosis. Treating them yourself with a herb can delay care for a serious liver problem.
• Liver support (traditional use): Animal studies show that extracts can reduce liver damage from chemicals such as carbon tetrachloride. This has not been repeated in people. There is no good evidence that taking Di Er Cao protects a healthy liver, reverses fatty liver or helps with alcohol-related liver damage. If you already have a liver condition, do not add this herb without your doctor's knowledge.
• Skin sores, boils and abscesses (traditional topical use): Traditionally the fresh crushed plant, or a strong decoction used as a wash, was applied to hot, swollen or infected skin. Lab work shows some activity against bacteria in a dish, which is consistent with the tradition but does not prove it works on human skin. A spreading, hot or painful skin infection needs medical care, not a home poultice.
• Snake and insect bites (traditional topical use): The crushed fresh herb has been applied to bites in southern Chinese folk practice, often alongside internal doses. There is no human trial evidence that it neutralises venom or reduces harm from a bite. A snakebite is a medical emergency. Go to hospital; do not rely on any plant.
• Sore throat and mouth sores (traditional use): Di Er Cao is classed in tradition as a heat-clearing herb and has been used as a gargle or drink for hot, sore throats. No human trials support this use. Any relief may simply come from warm fluid. A sore throat with high fever, drooling or trouble swallowing needs a doctor the same day.
• Diarrhoea with fever (traditional use): It has been used in folk practice for loose stools that come with fever, on the traditional reasoning that it clears damp-heat. There is no reliable human evidence for this, and the herb can itself upset the stomach in some people. Diarrhoea with blood, severe pain or signs of dehydration needs medical assessment.

Which foods are rich in Di Er Cao?

Di Er Cao is a medicinal herb, not a food, and it is not an ingredient in any normal diet.

What are the side effects of Di Er Cao?

• Nausea or stomach ache
• Loose stools or diarrhoea
• Poor appetite
• Skin rash or itching
• Greater sensitivity to sunlight, with easier burning (reported across the Hypericum group)
• Dizziness or headache
• Reduced effect of other medicines you take

Good to know:

Serious side effects are not well documented, but that is mostly because the herb has barely been studied in people, not because it has been shown to be safe.

The most likely everyday problems are stomach upset and loose stools. The most important risk is not a side effect at all: it is the herb weakening or clashing with prescription medicines.

Stop taking it and get advice if you develop a rash, yellow skin or eyes, dark urine, or unusual bruising or bleeding.

How much Di Er Cao should you take?

• Recommended daily: No modern, tested dose exists. Nothing here is a recommendation to self-treat. In traditional Chinese practice the usual range quoted for the dried herb is about 15 to 30 grams a day, simmered in water and drunk in two or three portions. Some texts quote 30 to 60 grams of the fresh plant. Product strengths vary enormously, so a capsule or granule dose cannot be worked out from these figures. If you use a product, follow its label and tell your doctor and pharmacist you are taking it.
• Best time of day: Traditionally the decoction is split into two or three servings taken through the day, often morning and evening. No time of day has been shown to matter.
• With or without food: Usually taken warm, between meals, in traditional practice. If it upsets your stomach, taking it with food may help.
• Time to effect: Unknown. Traditional practice expects a response within days for acute complaints, but there is no trial evidence to say how quickly, or whether, anything happens.
• How long to take it: Traditional use is short-term, over days to a few weeks, aimed at a specific problem rather than taken indefinitely. There is no safety data on long-term use. If you are using it for anything lasting more than two weeks, stop and get the underlying problem checked instead. Stop at once and seek advice if your skin or eyes turn yellow, your urine turns dark, or you feel unusually tired.