Mu Tong

What is Mu Tong?

Mu Tong is a Chinese herb name, not one single plant. It is restricted because herb sold under this name was often Aristolochia. That plant destroys the kidneys and causes cancer of the urinary tract.

The most famous poisoning outbreak is often told as this herb's story, and it is not. In the early 1990s a Belgian weight-loss clinic dispensed Aristolochia fangchi, sold as Fang Ji, in place of a harmless herb.

Mu Tong's own record of harm comes from Taiwan and mainland China, where Guan Mu Tong was widely used. More than a hundred women were harmed. Many lost kidney function, and many later developed cancer.

The same illness turned up in China, Taiwan, Japan and the Balkans. Doctors named it Chinese herb nephropathy, which means kidney damage caused by herbs.

Today the name Mu Tong is meant to refer to Akebia or Clematis stems. Those plants do not carry the poison. But cut stems look alike in a bag, and only lab testing can tell them apart.

What a tradition says about a herb is not proof that it works or that it is safe. The evidence that Mu Tong helps anything is thin. The evidence that Aristolochia harms people is very strong.

How does Mu Tong work?

The harm is far better understood than any benefit.

Aristolochic acid travels to the kidneys. It kills the cells that line the tiny filtering tubes inside them. Scar tissue takes their place, and the scarring builds up with each dose.

The acid also sticks to DNA in the cells that line the kidney, ureters and bladder. These marks change genes that normally hold cancer back. That is why tumours can appear long after the last dose.

Scarred kidneys do not grow back. Once enough filtering tissue is lost, the damage is permanent. Some people reach kidney failure within months.

On the benefit side, tradition held that Mu Tong made a person pass more urine and 'cleared heat'. Heat is a traditional idea, not something a doctor measures. Lab work on Akebia and Clematis stems is limited, and there is no good human proof of either effect.

What forms does Mu Tong come in?

Mu Tong is sold as dried, cut stem in bulk herb shops. It also sits inside ready-made Chinese formulas as powders, granules, pills and capsules.

The risk is highest when a label says only 'Mu Tong', 'Akebia' or 'Caulis Akebiae'. Labels have been wrong before. Products bought online or brought back from abroad are the hardest to check.

Some classic formula names still list Mu Tong on the box. The maker may have used any of several plants.

If you find such a product at home, do not take it. Take the packet to a pharmacist or doctor instead.

Where it comes from:

Mu Tong has long standing in Chinese herbal medicine and was treated as a common herb, not a rare one. Old texts grouped it with herbs said to move water and cool the body.

Practitioners of the past gave it for scanty, painful urination and for swelling. It also appeared in formulas meant to help milk flow after childbirth.

For much of the twentieth century, Chinese suppliers shipped Aristolochia manshuriensis under this name. The swap was routine and was not thought risky at the time.

Kidney doctors uncovered the danger only in the 1990s. China then removed Guan Mu Tong from its official list of approved herbs, the pharmacopoeia, in 2003. Formulas made since then are meant to use Akebia or Clematis.

What does Mu Tong help with?

• Painful or scanty urination: Tradition held that Mu Tong eased burning and helped urine flow. No good human trials test this. A doctor can test your urine instead. If it is an infection, it needs an antibiotic, not a herb.
• Swelling from fluid build-up: Old texts used Mu Tong to move water out of the body. There is no human trial behind this. Swelling can be a sign of heart, liver or kidney trouble. That needs a check-up, not a herb.
• Low milk supply after childbirth: Mu Tong appeared in formulas said to help milk flow. Nothing in human research supports this. It is also a very poor choice while feeding. What a mother takes can pass into her milk and reach the baby.
• Mouth sores and restlessness: Tradition linked these to 'heat' and used Mu Tong in cooling formulas. No human study backs it. A mouth sore that has not healed in three weeks should be looked at by a doctor or dentist.

What are the side effects of Mu Tong?

• Kidney damage that builds up and does not heal (from Aristolochia batches)
• Kidney failure needing dialysis, a machine that cleans the blood
• Cancer of the lining of the bladder, ureters or kidney, often years later
• Blood in the urine, or urine that looks pink, red or brown
• Passing much less urine than normal
• Tiredness, pale skin and poor appetite as the kidneys fail
• High blood pressure (hypertension)
• Feeling sick, vomiting and belly pain
• Mouth, throat and stomach irritation from Clematis species
• Loose stools

Good to know:

The worst harm is silent at first.

People poisoned by aristolochic acid often felt well while their kidneys scarred. Some needed dialysis within months of taking it.

Cancer of the urinary tract can show up five, ten or twenty years later. The risk stays even after you stop.

Stomach upset and a sore mouth come on faster. They are milder, and they are not a warning sign you can trust. Feeling fine does not mean your kidneys are fine.

Is Mu Tong legal where you live?

In the United Kingdom, it is against the law to sell medicines containing Aristolochia species, and Mu Tong has been named in UK safety warnings. In the United States, the FDA warned the public about aristolochic acid products in 2001 and stops such products at the border. In China, Guan Mu Tong (Aristolochia manshuriensis) was taken off the official list of approved herbs in 2003, while Akebia and Clematis Mu Tong remain legal there. Rules differ by country, so check with your own national medicines regulator.

Options to discuss with a clinician

Start with a doctor, because the problems Mu Tong was used for usually have a cause that can be found and treated.

For burning or frequent urination, ask for a urine test. A urine infection needs the right antibiotic.

For swelling, ask for checks on your heart, liver and kidneys. Treating the cause works better than pushing out water.

For low milk supply, a midwife or a lactation adviser can help with feeding position and how often you feed. That is the first step, before any herb.

For mouth sores, a doctor or dentist can look for causes such as low iron or low vitamin B12.

If you want to stay with Chinese herbal medicine, see a registered practitioner who uses tested, species-verified herbs. Ask them in writing whether any herb in your formula comes from the Aristolochia family. Tell your doctor about every herb and supplement you take.

Graded pages for the options named above:

• Vitamin B12 — evidence grade A, traditional tier T0