What is Tsudosan?

Tsudosan is a herbal formula from Kampo, the herbal medicine of Japan. It is a fixed mix of ten herbs and one mineral salt. In Kampo it counts as a single drug, and it is given whole, not tweaked herb by herb.

Its old name reads as "Passage-Freeing Powder". Kampo use aims it at constipation that comes with a full, tight belly. It is also used for pain and swelling after a fall or blow, and for period problems.

Human trial evidence is very thin. Tsudosan has long standing in Kampo, but long use is not proof that it works. It is a strong laxative, so read the safety notes below with care.

How does Tsudosan work?

The bowel effect is the part we understand best. Rhubarb root (daio) holds compounds that the gut turns into stimulants. These make the bowel wall push harder, so stool moves on.

Bosho, a sulfate salt, pulls water into the gut. That softens hard stool and adds bulk.

The rest is traditional thinking, not proven biology. Kampo frames this formula as clearing "blood stasis", an old idea about blood that has stopped flowing well. Safflower, sappan wood and angelica are the herbs said to do that work, but no trial has shown it in people.

What forms does Tsudosan come in?

Most people take it as dried extract granules in single-dose sachets. Tablets and loose powder are also sold.

A Kampo prescriber may instead boil the raw herbs into a tea. In Japan it is a listed Kampo product, and some brands need a prescription.

Where it comes from:

The recipe comes from a Chinese book of 1587, known in Japan as Manbyo Kaishun. Japanese doctors took it up and made it part of Kampo.

In old Japan, bone-setters gave it after falls and blows. It was also given for missed or painful periods. It is still prescribed in Japan today.

What does Tsudosan help with?

• Constipation with a full, tight, tender belly: This is the clearest use. Rhubarb root and the sulfate salt are well known laxatives, so a bowel movement is likely. No human trial has tested the whole formula against a dummy pill.
• Belly fullness and swelling after an injury: Kampo has used it this way for centuries, often after a fall or blow. Evidence is limited to case reports and prescriber notes. Get any hard knock to the belly checked by a doctor before taking anything.
• Bruising and pain after a fall or blow: Old texts say the blood-moving herbs help bruises clear. Lab and animal work hints at effects on blood flow. No human trial backs this up.
• Painful, late or missed periods: A common Kampo use, based on the same "blood stasis" idea. Human evidence is lacking. Never use it to try to bring on a late period if you could be pregnant.

Which foods are rich in Tsudosan?

1. Liquorice sweets and liquorice tea: they add more of the same licorice compound, so keep them low
2. Salty foods: they add to the salt load already in the formula

Practical Tips:

Drink plenty of water while you take it, and eat normally unless your prescriber says otherwise.

What are the side effects of Tsudosan?

• Belly cramps and griping pain
• Loose stools or watery diarrhoea
• Nausea and loss of appetite
• Low potassium (low levels of a key body salt), which can cause muscle weakness, cramps or an odd heartbeat
• Swollen ankles or face, and a rise in blood pressure, from the licorice in it
• Weight gain from held water
• Darker or yellow-brown urine, which is harmless
• Skin rash or itching
• A lazy bowel that needs the laxative to work, after long use

Good to know:

Cramps and loose stools are the common ones, and they come from the laxative herbs. They usually settle when you lower the dose or stop.

The licorice effects matter more. Low potassium and held water build up quietly over weeks, and can be serious for the heart. Stop and get advice if you feel weak, get muscle cramps, or notice swelling.

How much Tsudosan should you take?

• Recommended daily: For adults, dried extract granules are often given at about 7.5 g a day, split into two or three doses. Brands differ, so follow the label. There is no dose set by trials. A Kampo prescriber should set your amount, and lower doses are used for older or frail people. Start low and stop if you get cramps or loose stools.
• Best time of day: Usually before meals, often morning and evening. Many people take the last dose in the evening, since the bowel effect tends to come overnight.
• With or without food: Take it on an empty stomach, about 30 minutes before food, with warm water. If it upsets your stomach, take it with a little food instead.
• Time to effect: A bowel movement often comes in 6 to 12 hours, so often after the first dose. Belly fullness may ease over a few days. Any effect on bruising or periods would take weeks, and is not proven.
• How long to take it: Short use only. For constipation, days rather than weeks, and no more than about two weeks without advice. Check in with a prescriber if you want to keep going. Long use of stimulant laxatives can make the bowel lazy and drop your potassium (a key body salt).