Yu Zhen San
Do not self-treat with Yu Zhen San
Practitioner-prepared only. If a licensed practitioner is treating you, follow only what they say, and tell your doctor what you are taking.
If this is an emergency
Some reactions to Yu Zhen San 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 Yu Zhen San?
- Never use this formula instead of emergency medical care if you or someone else has a stiff jaw, neck stiffness or muscle spasms after a wound — that may be tetanus, which can kill.
- Never swallow raw, unprocessed Tian Nan Xing (Arisaema rhizome); it can burn and swell the mouth and throat badly enough to block breathing.
- Do not use if you are pregnant or trying to become pregnant: Arisaema is traditionally forbidden in pregnancy and has shown harm to unborn animals.
- Do not use if you are breastfeeding.
- Do not give it to a child, at any dose.
- Do not use if you are also taking an aconite-containing herb such as Fu Zi, Chuan Wu or Cao Wu.
- Do not use if you are taking a blood thinner such as warfarin or clopidogrel, unless your doctor has agreed.
- Do not use if you are taking sedatives, sleeping tablets, opioid painkillers or muscle relaxants such as diazepam.
- Do not use if you have liver disease or kidney disease (organs that clear medicines from the body).
- Do not use if you have a mouth ulcer, a sore throat, oesophagitis (an inflamed food pipe) or any swallowing problem.
- Do not use if you have ever had a reaction to Arisaema, Saposhnikovia or another plant in the same families.
- Do not drink alcohol with it, even though old texts tell you to take it in hot wine.
When should you see a doctor?
Call emergency services now if you have a clenched or stiff jaw, a stiff neck, muscle spasms, difficulty swallowing or difficulty breathing after any wound, even a small one. These are signs of tetanus, and it is treated in hospital.
Call emergency services if, after taking this formula, your tongue, lips or throat swell, your voice goes hoarse, or you struggle to breathe or swallow.
See a doctor the same day if your mouth or throat burns or goes numb, if you vomit repeatedly, or if the skin where you applied the powder blisters.
See a doctor before you start it at all if you take any prescription medicine, are pregnant or breastfeeding, or have a liver or kidney problem. And check whether your tetanus vaccination is up to date — that is the proven way to prevent this illness.
- What it is: Yu Zhen San, or True Jade Powder, is a 17th-century Chinese herbal powder of Arisaema and Saposhnikovia, listed here as a single drug entry (a TCM formula), historically used for lockjaw after a wound.
- Active ingredients: Tian Nan Xing (Arisaema rhizome) — calcium oxalate crystals, lectins, alkaloids, Fang Feng (Saposhnikovia root) — chromones such as cimifugin, coumarins, Sometimes Bai Zhi, Tian Ma, Qiang Huo or Bai Fu Zi
- Side effects: Can burn and swell the mouth and throat, sometimes badly enough to threaten breathing; also nausea, drowsiness and skin irritation.
- Pregnancy & breastfeeding: Avoid in pregnancy and while breastfeeding.
Educational information, not medical advice — ask your doctor or midwife.
What is Yu Zhen San?
Yu Zhen San, also called True Jade Powder, is a classical Chinese herbal formula. It is listed here as a single entry, though it is a TCM formula. Its two core herbs are Tian Nan Xing (Arisaema rhizome) and Fang Feng (Saposhnikovia root), ground to a powder.
Old Chinese texts used it for "lockjaw wind". That means stiff muscles, a clenched jaw and spasms after a dirty wound. Today we know that picture as tetanus, a life-threatening infection that needs hospital care, antitoxin and antibiotics.
One herb in it, Arisaema, is classed as toxic in China's official herb list (the pharmacopoeia). Many countries restrict it. Long use in a tradition is not proof of effect, and that gap matters across this page.
Evidence verdict: strong, long use in one tradition, but no published human trials. Treat it as history, not as a treatment.
How does Yu Zhen San work?
No one has shown how it works in people. The human studies have not been done.
The traditional idea is framed in Chinese medical language. Wind and phlegm are said to enter a wound and lock the sinews. That is said to cause rigid muscles and a clamped jaw.
Tian Nan Xing is described as clearing phlegm and stopping spasm. Fang Feng is said to release wind from the surface of the body. These are old ideas, not measured effects in the body.
Lab and animal work on the single herbs gives some hints. Saposhnikovia extracts cut swelling in animals, an anti-inflammatory effect. Processed Arisaema extracts calmed rodents and reduced fits, an anticonvulsant (seizure-calming) effect, at high doses.
None of this has been tested against tetanus in people. Animal results often do not carry over to us.
The gap is worth stating plainly. Tetanus comes from a toxin made by Clostridium tetani bacteria. That toxin locks the nerve signals that run to your muscles.
Nothing in this formula has been shown to block that toxin. Modern survival rests on antitoxin, wound cleaning and antibiotics. It also rests on muscle relaxants and help with breathing.
What forms does Yu Zhen San come in?
The classic form is a loose powder. Equal parts of the dried herbs are ground fine and taken by mouth. It was stirred into warm rice wine, and some powder was dusted on the wound.
Other forms you may see:
- A decoction, which is a strong water simmer of the herbs. Some modern practitioners make it this way, which is seen as safer than swallowing raw powder.
- Granules and pills, sold in some Chinese pharmacies. These usually hold processed Arisaema only.
It is not a normal over-the-counter product in most Western countries. Arisaema is a restricted toxic herb. Products sold online may hold raw rather than processed material, with no way for you to tell.
Where it comes from:
The formula appears in Waike Zhengzong (True Lineage of External Medicine). The surgeon Chen Shigong wrote it in 1617, during the Ming dynasty.
It sat in the surgery and wound part of Chinese medicine. It was used for wounds that led on to rigid muscles and a locked jaw. Formula textbooks have copied it ever since, and TCM schools still teach it as the standard formula for that picture.
Its place is as a teaching classic and a record of history. It has never been the front-line answer to tetanus in modern Chinese hospitals. There, doctors use antitoxin and intensive care.
What does Yu Zhen San help with?
- Tetanus and lockjaw: This is the formula's classic use and the reason it exists. No published human trials have tested it for tetanus. Tetanus is an emergency with a real risk of death. Hospitals treat it with tetanus antitoxin, wound cleaning, antibiotics, muscle relaxants and help with breathing. Call emergency services if you or someone else has a stiff jaw, a stiff neck or muscle spasms after any wound. Do not use this formula in place of that care.
- Muscle spasm and stiffness after a wound: Old texts say the formula eases rigid, spasming muscles caused by "wind" entering a wound. No human study has tested the formula for muscle spasm. Animal studies of processed Arisaema show some calming and anticonvulsant (seizure-calming) effects. But these were high-dose tests in rodents. Spasms after a wound are a warning sign of infection. They need urgent medical checks.
- Trismus, a jaw that clamps shut: Classical texts list a clenched jaw as the main sign the formula was picked for. There is no trial evidence in people. A jaw that will not open can also come from a dental infection, an injury or a jaw joint problem. Each of those needs a different treatment. Get it looked at rather than treated at home.
- Fits linked to wound infection: The historical record describes use for convulsions (fits) after injury. No human trial supports this. Fits are always a reason to call emergency services, whatever the suspected cause.
What are the side effects of Yu Zhen San?
- Burning, stinging or numbness in the mouth, tongue and throat
- Swelling of the tongue, throat or voice box, which can block breathing
- Hoarseness or loss of voice
- Nausea, vomiting and stomach pain
- Diarrhoea
- Drowsiness and dizziness
- Skin redness, itching or blistering where the powder touches skin
- Allergic reaction, including rash, wheeze or facial swelling
Good to know:
The serious risk here comes from Tian Nan Xing (Arisaema), which is officially classed as a toxic herb in China.
Raw or poorly processed Arisaema causes immediate, severe burning and swelling of the mouth and throat. Case reports from China describe tongue and throat swelling bad enough to threaten the airway, and this can happen from a single dose. Correctly processed Arisaema is far less irritating, but you usually cannot verify the processing yourself.
Milder effects such as nausea, loose stools and drowsiness are also reported. Any burning in the mouth, trouble swallowing or trouble breathing after a dose is an emergency — stop and get help straight away.
Options to discuss with a clinician
For every problem on this page there are better-studied routes, and each one begins as a conversation with a doctor, pharmacist or qualified practitioner rather than a swap you make on your own.
- **Fits (seizures) or muscle spasm and stiffness after a wound, a jaw that clamps shut (trismus), or any sign of lockjaw:** these are emergencies, not home-care problems. In the UK call 999 or go to A&E; in the US call 911. Tetanus is treatable in hospital with wound cleaning, antitoxin (a medicine that neutralises the toxin), antibiotics and breathing support, and delay is what makes it dangerous. - **Preventing this in the first place:** ask your GP, practice nurse or pharmacist whether your tetanus vaccination is up to date, and what the schedule is after a dirty or deep wound. This is the route with the strongest evidence behind it by a long way. - **A wound that looks infected — hot, swollen, spreading redness, pus, fever:** have it seen and assessed so the cause is identified, then ask what standard treatment fits. - **Ongoing spasm, stiffness or jaw problems with another cause:** ask a clinician to diagnose the cause first; a registered herbalist can then tell you what, if anything, has a plausible role alongside that care.
Review status
This page has not been signed off by a pharmacist and is not published. It is shown here for a policy decision only.