Ohta's Isan (太田胃散): ingredients, dose and warnings in English
Ohta's Isan (太田胃散) is sold in Japan as a class 2 medicine: the box reads 第2類医薬品. In 1.3 g: Cinnamon Bark 92 mg, Fennel 24 mg, Nutmeg 20 mg, Clove 12 mg, Citrus Unshiu Peel 22 mg, Gentian 15 mg and 6 more. The package insert sets the adult dose at 1.3 g, 3 times a day, for ages 8 and over.
第2類医薬品 · Class 2
What is in Ohta's Isan
The package insert lists 12 active ingredients in 1.3 g. The middle column is how each one is written on the Japanese box.
| Ingredient | Name on the box | Amount |
|---|---|---|
| Cinnamon Bark | ケイヒ | 92 mg |
| Fennel | ウイキョウ | 24 mg |
| Nutmeg | ニクズク | 20 mg |
| Clove | チョウジ | 12 mg |
| Citrus Unshiu Peel | チンピ | 22 mg |
| Gentian | ゲンチアナ | 15 mg |
| Powdered Picrasma Wood | ニガキ末 | 15 mg |
| Sodium Bicarbonate | 炭酸水素ナトリウム | 625 mg |
| Precipitated Calcium Carbonate | 沈降炭酸カルシウム | 133 mg |
| Magnesium Carbonate | 炭酸マグネシウム | 26 mg |
| Synthetic Aluminum Silicate | 合成ケイ酸アルミニウム | 273.4 mg |
| Biodiastase * | ビオヂアスターゼ | 40 mg |
* No official English name in the Japanese Accepted Names (JAN) database or the Japanese Pharmacopoeia. The English here describes the Japanese name; the name on the box is in the middle column.
Additives, as written on the package insert (Japanese)
l-メントール
The maker publishes an English product page for Ohta's Isan: Ohta's Isan: Ohta's Isan (English product page). This page translates the current Japanese package insert on PMDA.
Source: PMDA (Pharmaceuticals and Medical Devices Agency) — 太田胃散: package insert (添付文書) · Ohta's Isan — Ohta's Isan: English product page
What the package insert lists it for
The approved wording of the Japanese package insert, translated. It is what the product is sold for, not advice on what to take.
- Drinking too much, heartburn, stomach discomfort, weak stomach, heavy stomach, overeating, stomach pain, indigestion, promotion of digestion, loss of appetite, excess stomach acid, a bloated feeling in the stomach/abdomen, nausea (queasy stomach, queasiness from a hangover/feeling ill after drinking, feeling sick), vomiting, a feeling of something stuck in the chest, belching, a heavy feeling in the stomach
The dose, as written on the package insert
Translated line by line from the directions and dosage (用法・用量) section.
- Adult dose
- 1.3 g
- Doses a day
- 3
- Age
- 8 and over
- On the box
- 第2類医薬品
- Adults (15 and over): 1.3 g per dose; ages 8 to 14: 0.65 g per dose; take it 3 times a day after meals or between meals. (1 level spoonful of the spoon provided is about 1.3 g. Use the levelling plate on the back of the inner lid. Between meals means 2 to 3 hours after a meal.)
Notes on the directions
- Take it with water or lukewarm water.
- When giving it to children, have them take it under the guidance and supervision of a parent or guardian.
Do not
The package insert opens with what you must not do.
1. Do not take it if you are receiving dialysis treatment
2. Do not keep taking it for a long time
Ask a doctor, pharmacist or registered salesperson
The package insert says to ask for advice in these cases.
1. If you are one of the following people, ask a doctor, pharmacist or registered salesperson for advice before taking it
- (1) People who are receiving treatment from a doctor.
- (2) People who have had allergic symptoms caused by medicines etc.
- (3) People who have been diagnosed with kidney disease or thyroid dysfunction.
2. If symptoms of rash/redness or itching appear on the skin after taking it, they may be side effects, so stop taking it immediately and ask a doctor, pharmacist or registered salesperson for advice, taking this leaflet with you
3. If your symptoms do not improve after taking it for about 2 weeks, stop taking it and ask a doctor, pharmacist or registered salesperson for advice, taking this leaflet with you
Who can sell it in Japan
The Ohta's Isan box carries the class 第2類医薬品, which decides who may sell it.
- On the box
- 第2類医薬品 (Class 2). The box reads 第2類医薬品.
- Who can sell it
- A pharmacist or a registered salesperson may sell it.
Source: e-Gov law search (Digital Agency, Japan) — Pharmaceutical and Medical Device Act (医薬品医療機器等法), current text · e-Gov law search (Digital Agency, Japan) — Enforcement Regulations of the Pharmaceutical and Medical Device Act (施行規則), current text
Taking it home
Frequently asked questions
How much Ohta's Isan can an adult take in a day?
The package insert sets the adult dose at 1.3 g, 3 times a day.
Can children take Ohta's Isan?
The package insert gives doses from age 8 and says it is not to be taken below that age.
Do I need a pharmacist to buy Ohta's Isan?
Ohta's Isan is a class 2 medicine (第2類医薬品). A pharmacist or a registered salesperson may sell it.
What is Ohta's Isan called in Japanese?
太田胃散. The Ohta's Isan box also carries the class 第2類医薬品.
Related items
Package insert in Japanese: PMDA
Sources for this page
- PMDA (Pharmaceuticals and Medical Devices Agency) 太田胃散: package insert (添付文書)checked October 3, 2026
- Ohta's Isan: English product pagechecked October 3, 2026
- e-Gov law search (Digital Agency, Japan) Pharmaceutical and Medical Device Act (医薬品医療機器等法), current textchecked October 3, 2026
- e-Gov law search (Digital Agency, Japan) Enforcement Regulations of the Pharmaceutical and Medical Device Act (施行規則), current textchecked October 3, 2026
Compiled by Japan Japan !! · Updated October 3, 2026