Cang Er Zi
Do not self-treat with Cang Er Zi
Practitioner-prepared only. Take it only on the advice of a qualified herbal practitioner.
If this is an emergency
Some reactions to Cang Er Zi need urgent care. Call your local emergency number or go to an emergency department straight away — do not wait to see whether it passes.
Who should avoid Cang Er Zi?
- Do not use if you are pregnant or trying to become pregnant.
- Do not use if you are breastfeeding.
- Never give it to a child; children have died from cocklebur poisoning.
- Do not use if you have any liver disease, hepatitis (liver inflammation) or a history of liver injury from a medicine.
- Do not use if you have kidney disease.
- Do not use if you have diabetes and take insulin or blood-sugar-lowering tablets.
- Do not use if you drink alcohol regularly, and do not drink alcohol while taking it.
- Do not use if you take paracetamol (acetaminophen) regularly, methotrexate, statins, or TB medicines such as isoniazid or rifampicin.
- Do not use if you take warfarin or another blood thinner.
- Never eat the raw fruit, the seeds or the young seedlings, and never forage cocklebur from the wild.
- Do not take it without supervision from a qualified herbal practitioner, and never exceed the amount you were given.
- Do not use if you have had a rash or allergic reaction to cocklebur or to plants in the daisy family.
When should you see a doctor?
Stop taking it and get medical help straight away if you feel sick, vomit, have belly pain, feel unusually tired or confused, or notice yellow skin or eyes, dark urine or pale stools. These can be signs of liver injury.
Call emergency services if someone has a seizure (fit), collapses, cannot be woken, or has taken a large amount or eaten the raw plant. Take the product or plant with you so doctors know what was swallowed.
See your doctor rather than self-treating if a blocked nose, sinus pain or facial pressure lasts more than about ten days, comes with fever, or keeps coming back.
- What it is: Cang Er Zi is the dry-fried fruit of the cocklebur plant, used in Traditional Chinese Medicine for a blocked nose, and known to be toxic if raw or overdosed.
- Active ingredients: Xanthatin and xanthinin (sesquiterpene lactones), Caffeoylquinic acids (plant antioxidants), Carboxyatractyloside (the toxic constituent)
- Side effects: Commonly nausea and headache; rarely severe liver injury, low blood sugar, seizures and death.
- Pregnancy & breastfeeding: Avoid in pregnancy and while breastfeeding.
Educational information, not medical advice — ask your doctor or midwife.
What is Cang Er Zi?
Cang Er Zi is used in Traditional Chinese Medicine for a blocked, runny or stuffy nose. It is the dried, spiny fruit of the cocklebur plant (Xanthium sibiricum and close relatives). It is a single herb, not a blend.
It is almost always cooked into a formula. It is rarely taken on its own.
It is also the herb most often linked to bad poisoning in the Chinese herb books. The raw fruit and the young seedlings hold a natural poison. That poison can harm the liver, and in reported cases it has killed.
For this reason the fruit is dry-fried before use. A trained practitioner gives it only in small, short courses.
On the evidence: its place in tradition is old and strong. But human trial proof for the single herb is very thin.
Long use tells you that people have leaned on it for many years. It does not prove that the herb works. That point is made here once, and not repeated in each section below.
How does Cang Er Zi work?
No one has shown clearly how Cang Er Zi works in people. In TCM terms it is said to open the nose. It is also said to disperse "wind-cold" and ease damp, aching joints.
Lab and animal studies report some effects. Extracts can cut inflammation (swelling and soreness) in nose tissue. They can also calm some allergy signals.
That work is early. Good human trials have not backed it up.
The toxic side is better known. The fruit holds carboxyatractyloside. This blocks the way liver cells make energy.
That is the accepted reason for the liver failure and low blood sugar seen in poisoning cases.
What forms does Cang Er Zi come in?
The usual form is the dry-fried whole fruit. It is simmered with other herbs into a decoction (a strong water-based tea).
Forms you may meet: - Dry-fried whole fruit, cooked into a decoction - Pills and granules of classic formulas - The well-known nose formula Cang Er Zi San - Shop-bought "Bi Yan" nose products - Nose drops and oils
Raw, unprocessed fruit is behind most poisoning reports. Home-made brews from wild cocklebur are too. Do not make your own.
Where it comes from:
Cang Er Zi shows up in Chinese medical texts from about the Tang dynasty. It is listed in the Chinese Pharmacopoeia today.
Its classic role is narrow and steady. It clears a blocked nose and eases wind-damp joint pain. Chinese sources have carried warnings about its toxicity for hundreds of years.
What does Cang Er Zi help with?
- Blocked or stuffy nose: This is the classical use and the main reason the herb is still prescribed. Practitioners use it for a few days at a time as part of a formula. Good human trials of the single herb are lacking, so the support here is traditional rather than proven.
- Allergic rhinitis (hay fever-type nasal allergy): Cang Er Zi San and similar formulas are widely used in China for sneezing, itching and a runny nose. Most published studies are small, Chinese-language and test multi-herb mixtures, so any effect cannot be pinned to this herb. Standard allergy treatments have far stronger evidence.
- Chronic sinusitis (long-term sinus inflammation): Traditional texts describe it for thick nasal discharge and facial pressure. Lab work suggests anti-inflammatory activity, but no reliable human trial of the herb alone supports it. Long-term sinus problems need a doctor's assessment.
- Headache from nasal congestion: Classical sources pair it with Xin Yi Hua for a dull frontal headache that comes with a blocked nose. This is traditional practice only; we found no human trial testing it for headache.
- Wind-damp joint aches (a TCM pattern): A secondary traditional use for stiff, achy joints made worse by cold or damp weather. Evidence in people is essentially absent. Do not substitute it for treatment of arthritis.
- Itchy skin rashes (external traditional use): Decoctions have been used as a wash for itchy skin. Skin contact with the plant can itself cause rash in some people. There is no trial evidence for this use.
What are the side effects of Cang Er Zi?
- Nausea and vomiting
- Stomach pain and diarrhoea
- Headache and dizziness
- Drowsiness or feeling weak
- Skin rash or itching, including from handling the plant
- Liver injury, which can be severe and has caused deaths
- Low blood sugar (hypoglycaemia), which can cause shaking, confusion or fainting
- Kidney damage in serious poisoning
- Seizures (fits) and coma in serious poisoning
Good to know:
Mild stomach upset and headache are the common complaints. The serious effects are rare but real, and they are the reason this herb is treated with unusual care.
Published case series from China describe liver failure and deaths, mostly after raw fruit, overdose, or eating young cocklebur seedlings as a wild green. Children have been affected most severely.
Stop the herb and get medical help at the first sign of vomiting, belly pain, yellow skin or eyes, or confusion.
Options to discuss with a clinician
What gentler options could you ask about?
If a blocked or runny nose is the problem, there are milder things worth raising. A simple salt-water nasal rinse and steam inhalation are low-risk and easy to try. In Chinese herbal practice, Xin Yi Hua (magnolia flower) is a gentler herb used for the same complaint.
Bring any of these to your doctor, or to a qualified herbal clinician, before you start. They can look at your liver health, your other medicines and your symptoms. That way the choice is matched to you, not a guess.
Graded pages for the options named above:
- Xin Yi Hua (Magnolia Flower) — evidence grade D, traditional tier T3
- Steam Inhalation — evidence grade C, traditional tier T3
Review status
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