What is Shimotsuto?

Shimotsuto is a herbal mix used in Kampo, the herbal medicine of Japan. It is made from four dried roots, boiled as a tea or taken as granules. The name means "four substance drink".

It is given for tiredness, pale skin, dry skin and period problems. In Kampo terms, it is for people said to be low in "blood". That idea is not the same as a blood test result.

It sits on the Japanese health ministry's list of 148 Kampo formulas paid for by national health insurance. But long use in a tradition is not proof that a remedy works. Human trials of this mix are few and weak, so we cannot say how well it works.

How does Shimotsuto work?

The honest answer is that no one has shown how it works in the body.

In Kampo, the four roots are said to build and move "blood". Two of them are said to feed it. The other two are said to keep it flowing.

Lab work gives a few hints. Peony root and angelica root slow clotting in the test tube. Some parts appear to calm swelling in cells.

None of that has been shown to matter in people who take the formula. Treat the lab findings as a reason to be careful, not as proof of benefit.

What forms does Shimotsuto come in?

Most people take it as extract granules. A sachet of powder is stirred into hot water and drunk.

You can also find it as tablets or capsules, which are easier to carry but taste less strong. Some pharmacies sell the raw cut roots for boiling at home, which takes about 30 to 40 minutes.

In Japan, brands made to the national standard are tightly checked. Products bought outside Japan vary a lot in strength, so check the label for the herb amounts.

Where it comes from:

Shimotsuto began in China as Si Wu Tang, written down in a Song dynasty formula book from about 1107.

Japanese doctors took it up and it became one of the base formulas of Kampo. Many other Kampo mixes are built by adding herbs to these four roots.

It is still in daily use in Japan, Korea and China, which is why its traditional standing is strong even though the trial record is not.

What does Shimotsuto help with?

• Painful or irregular periods: This is the most common reason it is prescribed in Japan. Kampo has used it this way for centuries. The human trial evidence is thin. The few studies are small, often on the Chinese version, and usually add other herbs or drugs, so you cannot tell what the formula did on its own.
• Tiredness and pale skin linked to low iron: Tradition uses it for the pattern it calls "blood deficiency", which looks like tiredness, pale skin and dizziness. It is not an iron supplement and will not correct anaemia (a low red blood cell count). If blood tests show you are low in iron, you need iron, not this. Ask your doctor first.
• Recovery after childbirth: A long-standing traditional use in Japan and China for weakness and slow recovery after birth. There are no good trials of this. If you are breastfeeding, do not start it without asking your doctor, because the herbs pass into milk and this has not been studied.
• Dry, rough or itchy skin: Kampo links dry skin to poor "blood" nourishment, so this formula is a standard choice. Evidence in people is limited to case reports and small Japanese studies. We could not find a controlled trial we would rely on.
• Cold hands and feet: Traditionally used for people who feel the cold and have poor colour in the fingers. No reliable human trial supports this. Cold hands can also come from thyroid problems or circulation disease, so get lasting symptoms checked.
• Menopause complaints: It is one of several Kampo formulas offered in Japan for hot flushes and mood changes around menopause. Other Kampo mixes have been studied more for this. For Shimotsuto alone, the human evidence is very thin.

Which foods are rich in Shimotsuto?

1. Japanese angelica root (toki): a bitter root sometimes simmered in home broths
2. Peony root (shakuyaku): a herb-shop item, not a kitchen food
3. Rehmannia root (jio): steamed until black and sweet, used in tonic soups
4. Cnidium rhizome (senkyu): aromatic and used in herbal soups only

Practical Tips:

These are the formula's own ingredients. There is no ordinary food that contains Shimotsuto.

What are the side effects of Shimotsuto?

• Nausea or a heavy, uncomfortable stomach
• Loose stools or diarrhoea
• Loss of appetite
• Skin rash or itching
• Rarely, signs of liver trouble such as yellow skin or eyes, dark urine or deep tiredness
• Rarely, easy bruising or bleeding that is slow to stop

Good to know:

Most people who stop do so because of the stomach. Rehmannia root is the usual culprit, and lowering the dose or taking it with food often fixes it.

Serious harm is rare, but liver injury has been reported with Kampo formulas in general. Bruising and bleeding matter most if you already take a blood-thinning medicine.

Stop the formula and speak to a doctor if a rash spreads, or if your skin or eyes turn yellow.

How much Shimotsuto should you take?

• Recommended daily: The standard Japanese dose of extract granules is about 7.5 g a day, split into two or three doses. If you boil the raw roots, a common daily amount is 3 to 5 g of each of the four roots in one pot of water. Start at the low end. Older adults and smaller people often do well on two thirds of the adult dose.
• Best time of day: Kampo custom is to take it on an empty stomach, so before meals or between them. Splitting it across the day suits most people.
• With or without food: Best about 30 minutes before food, or between meals. If it upsets your stomach, take it with a little food instead.
• Time to effect: Expect weeks, not days. Period-related changes are usually judged over two or three cycles.
• How long to take it: Give it four weeks, then think it over. If nothing at all has changed by eight weeks, stop and see your doctor. Long courses of several months are used in Japan under a prescriber who checks in. Do not run a long course on your own.