Ota-isan Guide: Japan's Stomach Medicine, Powder vs Tablet, Dosage & Price
Tokyo Mate
Ota-isan is one of Japan's best-known stomach medicine brands, founded in 1879. This guide covers the difference between powder Ota-isan S, the easy-to-carry single-pack Ota-isan Bunpo S, and tablet Ota-isan A, along with how to take each product, the 7 herbal ingredients, Japanese prices, and tips for buying at drugstores and Don Quijote, updated for 2026.
What Is Ota-isan? Japan’s 140-Year-Old Digestive and Stomach Medicine
Ota-isan (太田胃散) is a leading Japanese stomach medicine brand founded in 1879. Starting with its powder-type all-purpose stomach medicine, it now runs a wide lineup that includes tablets, chewables, herbal stomach medicines, and intestinal regulators.
In Korea, it is also well known among travelers looking for Japanese stomach medicine or a digestive aid from Don Quijote. Its signature products are the powder Ota-isan S and the Ota-isan A tablets, used for stomach discomfort after greasy food or overeating.
Ota-isan Stomach Medicine Types & Prices: Powder, Tablet & Chewable Lineup
Ota-isan sells not only its signature powder-type all-purpose stomach medicine but also tablets, chewables, herbal stomach medicines, and intestinal regulators.
Each product has different ingredients, official indications, eligible ages, and timing for taking it. When buying in Japan, don't just go by the packaging format. Check the Japanese product name and drug classification printed on the package.
※ The prices below are the official prices listed on the Ota-isan official website, all tax included. Actual drugstore selling prices may vary by store, season, and sales promotion.
① Ota-isan S (太田胃散S)
| Classification | Class 2 OTC drug |
| Form | Powder |
| Size | Can: 80g / 150g |
| Official price | 80g ¥924 / 150g ¥1,639 |
| Features | A powder-type all-purpose stomach medicine combining 7 stomachic herbs, 3 antacids, and the digestive enzyme biodiastase. Used for excess drinking and eating, heartburn, excess stomach acid, stomach pain, indigestion, and bloating. |
② Ota-isan Bunpo S (太田胃散〈分包〉S)
One adult dose comes individually wrapped in a single packet, making it easy to carry while traveling in Japan or out and about.
| Classification | Class 2 OTC drug |
| Form | Powder |
| Size | Single packets: 18 / 34 / 50 packets |
| Official price | 18 pkt ¥842 / 34 pkt ¥1,507 / 50 pkt ¥2,079 |
| Features | The same ingredients and official indications as the canned Ota-isan S. |
③ Ota-isan A Tablets (太田胃散A〈錠剤〉)
The 45-tablet product comes individually wrapped in sets of 3 tablets, which is one adult dose.
| Classification | Class 2 OTC drug |
| Form | Tablet |
| Size | 45 / 120 / 300 tablets |
| Official price | 45 ct ¥748 / 120 ct ¥1,320 / 300 ct ¥2,508 |
| Features | A tablet-type stomach medicine combining Lipase AP6, which digests fat, the protein-digesting enzyme Prozyme 6, and Biodiastase 1000, which helps digest carbohydrates and protein. Ursodeoxycholic acid promotes bile secretion to aid fat digestion. |
④ Ota-isan Chewable NEO (太田胃散チュアブルNEO)
| Classification | Class 3 OTC drug |
| Form | Chewable tablet |
| Size | 18 tablets |
| Official price | ¥880 |
| Features | A lemon-lime stomach medicine you chew or let dissolve in your mouth without water. Three antacids neutralize excess stomach acid, and dimethylpolysiloxane reduces gas built up in the stomach, working to relieve heartburn, stomach bloating, and stomach discomfort. |
⑤ Ota-isan Peinon Tablets (太田胃散ペイノン錠)
| Classification | Class 2 OTC drug |
| Form | Tablet / individually wrapped |
| Size | 6 tablets |
| Official price | ¥1,100 |
| Features | Tiquizium bromide 5mg suppresses stomach acid secretion and relaxes gastrointestinal tension. A tablet-type stomach medicine for sudden stomach and abdominal pain and cramping abdominal colic. |
⑥ Ota-isan Intestinal Regulator (太田胃散整腸薬)
| Classification | Class 3 OTC drug |
| Form | Tablet |
| Size | 160 / 370 tablets |
| Official price | 160 ct ¥1,518 / 370 ct ¥2,948 |
| Features | An intestinal regulator combining 3 live gut bacteria (Bifidobacterium, Lactobacillus gasseri, and butyric acid bacteria) with the herbs geranium and Mallotus japonicus. Used to regulate disrupted bowel conditions such as loose stools, constipation, and abdominal bloating. |
⑦ Ota-isan Intestinal Regulator De-Rumoa Tablets (太田胃散整腸薬 デ・ルモア錠)
| Classification | Class 3 OTC drug |
| Form | Tablet |
| Size | 90 / 180 tablets |
| Official price | 90 ct ¥1,078 / 180 ct ¥1,848 |
| Features | A constipation-focused intestinal regulator combining Bifidobacterium, Lactobacillus gasseri, and butyric acid bacteria with cassia seed extract. Used for constipation, loose stools, abdominal bloating, and regulating bowel conditions. Where the regular Ota-isan Intestinal Regulator covers loose stools and constipation broadly, De-Rumoa tablets focus on constipation. |
⑧ Ota Kampo Stomach Medicine II (太田漢方胃腸薬Ⅱ)
| Classification | Class 2 OTC drug |
| Form | Herbal granules / individually wrapped |
| Size | 14 / 34 packets |
| Official price | 14 pkt ¥1,078 / 34 pkt ¥2,420 |
| Features | A granule-type stomach medicine formulated with the herbal prescription anchusan-ka-buryo. Used for nervous gastritis, chronic gastritis, and weak digestion brought on by stress such as anxiety and tension, or by constitution. |
⑨ Ota Kampo Stomach Medicine II Tablets (太田漢方胃腸薬Ⅱ〈錠剤〉)
| Classification | Class 2 OTC drug |
| Form | Tablet |
| Size | 54 / 120 tablets |
| Official price | 54 ct ¥1,078 / 120 ct ¥2,046 |
| Features | A tablet-type herbal stomach medicine with the same active ingredients and official indications as the granule Ota Kampo Stomach Medicine II. You can choose whichever form is easier to take. |
⚠️ Check for discontinued products: Ota-isan renamed to Ota-isan S
The original canned Ota-isan in 75g / 140g / 210g and the packet-type Ota-isan in 16 / 32 / 48 packets ended production in September 2025.
The current products have been changed to the canned 80g / 150g Ota-isan S and the single-pack 18 / 34 / 50 packet Ota-isan Bunpo S. When buying at a store in Japan, check that there is an "S" after the product name.
Ota-isan Convenience Store Products & Prices: NEXT & Onaka Support
Ota-isan S and Ota-isan A are OTC drugs sold at pharmacies and drugstores. Ota-isan NEXT, NEXT Tablets, and Onaka Support, on the other hand, are designated quasi-drugs that can also be sold at convenience stores. Their ingredient makeup and official indications differ from the OTC drugs, so check the product name and use when buying at a convenience store.
① Ota-isan NEXT (太田胃散NEXT)
| Classification | Designated quasi-drug (convenience store product) |
| Form | Powder |
| Size | 3 single packets |
| Official price | ¥297 |
| Features | A powder-type stomachic refresher combining 4 herbs and ursodeoxycholic acid. Used for stomach discomfort and nausea from overeating or excess drinking, and a portable product you can buy at convenience stores. |
② Ota-isan NEXT Tablets (太田胃散NEXT錠)
| Classification | Designated quasi-drug (convenience store product) |
| Form | Tablet |
| Size | 4 tablets / 2 adult doses |
| Official price | ¥220 |
| Features | A tablet product with the same active ingredients and official indications as the powder NEXT. It contains 2 doses of 2 tablets each for an adult, used for stomach discomfort and nausea from overeating or excess drinking. |
③ Ota-isan Onaka Support (太田胃散おなかサポート)
| Classification | Designated quasi-drug (convenience store product) |
| Form | Tablet / zipper pouch |
| Size | 36 tablets / 9 adult doses |
| Official price | ¥440 |
| Features | An intestinal and digestive aid combining the human-derived lactic acid bacterium Conc. Biozenin, natto bacteria, and the digestive enzyme biodiastase. Used for loose stools, constipation, and abdominal bloating, as well as overeating, indigestion, and stomach heaviness. Ota-isan Onaka Support is sold at FamilyMart stores nationwide in Japan. |
Ota-isan S vs Ota-isan A: A Selection Guide
Ota-isan S and Ota-isan A are both all-purpose stomach medicines used for various stomach symptoms, but they are not simply a powder and a tablet version of the same thing. Their herb and digestive-ingredient makeup differs, so check each product's features before choosing.
✅ Ota-isan S vs Ota-isan A comparison
| Item | Ota-isan S / Bunpo S | Ota-isan A |
|---|---|---|
| Classification | Class 2 OTC drug | Class 2 OTC drug |
| Form | Powder | Tablet |
| Size | Can 80g / 150g; packets 18 / 34 / 50 | 45 / 120 / 300 tablets |
| Features | 7 herbs, 3 antacids, biodiastase | 3 digestive enzymes, ursodeoxycholic acid, 3 antacids |
| Herbal ingredients | Cinnamon, fennel, nutmeg, clove, dried citrus peel, gentian, quassia powder | Cinnamon oil, lemon oil, fennel oil |
| Digestive ingredients | Biodiastase | Lipase AP6, Prozyme 6, Biodiastase 1000, ursodeoxycholic acid |
| Indications | A powder all-purpose stomach medicine for various stomach symptoms such as excess drinking and eating, heartburn, excess stomach acid, and indigestion | A tablet all-purpose stomach medicine for stomach heaviness and heartburn from greasy food such as meat |
✅ What kind of product is Ota-isan S?
Ota-isan S is a powder-type all-purpose stomach medicine combining 7 herbs that support stomach function, 3 antacids that neutralize stomach acid, and the digestive enzyme biodiastase.
The herbs' distinctive aroma and bitterness regulate stomach function and gastric secretion, while the antacids neutralize excess stomach acid. Biodiastase helps digest carbohydrates, protein, and the like.
Its official indications include excess drinking and eating, heartburn, excess stomach acid, stomach discomfort, bloating, abdominal distension, stomach pain, indigestion, loss of appetite, nausea and vomiting, and belching.
✅ What kind of product is Ota-isan A?
Ota-isan A contains Lipase AP6, which breaks down fat, Prozyme 6, which digests protein, and Biodiastase 1000, which helps digest carbohydrates and protein. On top of that, ursodeoxycholic acid promotes bile secretion to aid fat digestion.
Ursodeoxycholic acid is not a digestive enzyme but a digestive ingredient that aids fat digestion. Ota-isan A is a tablet-type all-purpose stomach medicine used for stomach heaviness and heartburn from greasy food such as meat, as well as overeating, indigestion, stomach pain, and excess stomach acid.
⚠️ Ota-isan S and Ota-isan A differ in their eligible ages and single dose, so after buying, check the dosage on the product package and package insert.
How to Take Ota-isan: Dosage & Timing by Product
Ota-isan products differ in single dose, eligible age, and timing: after meals, on an empty stomach, before bed, and so on. Even within the same Ota-isan brand, the powder, tablet, intestinal regulator, and herbal stomach medicine each have a different way to take them, so check the exact product name on the package.
| Product | Dose | When & how |
|---|---|---|
| Ota-isan S 太田胃散S | 15+: 1.3g per dose, 3×/day 8-14: 0.65g per dose, 3×/day Under 8: do not take | After a meal, or 2-3 hours after a meal, with water or lukewarm water |
| Ota-isan Bunpo S 太田胃散〈分包〉S | 15+: 1 packet per dose, 3×/day 8-14: 1/2 packet per dose, 3×/day Under 8: do not take | After a meal, or 2-3 hours after a meal, with water or lukewarm water |
| Ota-isan A Tablets 太田胃散A〈錠剤〉 | 15+: 3 tablets per dose, 3×/day 8-14: 2 tablets per dose, 3×/day 5-7: 1 tablet per dose, 3×/day Under 5: do not take | After a meal, or 2-3 hours after a meal. May be taken before bed. Take before a meal for loss of appetite. May be chewed. At least 4 hours apart |
| Ota-isan Chewable NEO 太田胃散チュアブルNEO | 15+: 2 tablets per dose, 3×/day Under 15: do not take | Regardless of meals, when you have symptoms, chew without water or let dissolve in your mouth. At least 4 hours apart |
| Ota-isan Peinon Tablets 太田胃散ペイノン錠 | 15+: 1 tablet per dose, up to 3×/day Under 15: do not take | Regardless of meals, when you have stomach or abdominal pain, with water or lukewarm water. At least 5 hours apart |
| Ota-isan Intestinal Regulator 太田胃散整腸薬 | 15+: 3 tablets per dose, 3×/day 8-14: 2 tablets per dose, 3×/day 5-7: 1 tablet per dose, 3×/day Under 5: do not take | After a meal, with water or lukewarm water |
| Ota-isan Intestinal Regulator De-Rumoa Tablets 太田胃散整腸薬 デ・ルモア錠 | 15+: 3 tablets per dose, 3×/day 8-14: 2 tablets per dose, 3×/day 5-7: 1 tablet per dose, 3×/day Under 5: do not take | After a meal, with water or lukewarm water |
| Ota Kampo Stomach Medicine II 太田漢方胃腸薬Ⅱ | 15+: 1 packet per dose, 3×/day 7-14: 2/3 packet per dose, 3×/day Under 7: do not take | 2-3 hours after a meal, before bed, or on an empty stomach, with water or lukewarm water |
| Ota Kampo Stomach Medicine II Tablets 太田漢方胃腸薬Ⅱ〈錠剤〉 | 15+: 3 tablets per dose, 3×/day 7-14: 2 tablets per dose, 3×/day Under 7: do not take | 2-3 hours after a meal, before bed, or on an empty stomach, with water or lukewarm water |
| Ota-isan NEXT 太田胃散NEXT | 15+: 1 packet per dose, 3×/day Under 15: do not take | After a meal, or 2-3 hours after a meal, with water or lukewarm water |
| Ota-isan NEXT Tablets 太田胃散NEXT錠 | 15+: 2 tablets per dose, 3×/day Under 15: do not take | After a meal, or 2-3 hours after a meal, with water or lukewarm water |
| Ota-isan Onaka Support 太田胃散おなかサポート | 15+: 4 tablets per dose, 3×/day 8-14: 2 tablets per dose, 3×/day 5-7: 1 tablet per dose, 3×/day Under 5: do not take | After a meal, with water or lukewarm water |
✅ Tips for taking Ota-isan
- If you find the powder Ota-isan S or Bunpo S hard to swallow, first hold a little water in your mouth, then add the powder, mix it with your tongue 2-3 times, and swallow, which makes it easier to take.
- Ota-isan Chewable NEO can be taken without water, but Ota-isan S, Bunpo S, and NEXT should be taken with water or lukewarm water.
- Ota-isan A is taken after a meal or 2-3 hours after a meal, and may also be taken before bed. When taking it for loss of appetite, take it before a meal.
- The Ota Kampo Stomach Medicine II granules and tablets are taken 2-3 hours after a meal, before bed, or on an empty stomach.
✅ Before taking
- If you are taking other medications, check with a doctor or pharmacist whether they can be taken together.
- Eligible ages differ by product, so when giving it to a child, check the dose for their age.
- If symptoms such as rash or itching appear, stop taking it and consult a doctor or pharmacist.
- If symptoms persist or worsen, don't just keep taking it. Get examined at a medical institution.
- If you are pregnant or breastfeeding, or have a condition under treatment, the criteria for taking it differ by product, so consult a doctor or pharmacist before taking it.
Ota-isan FAQ
Q. How is Ota-isan different from Kabagin?
Ota-isan S and Kabagin Kowa α Plus are both Japanese stomach medicines, but their main ingredients and product features differ.
Ota-isan S is a powder-type all-purpose stomach medicine combining 7 stomachic herbs, 3 antacids, and the digestive enzyme biodiastase. It is used for various stomach symptoms such as excess drinking and eating, heartburn, excess stomach acid, indigestion, and bloating.
Kabagin Kowa α Plus is a tablet-type stomach medicine combining MMSC with antacids, herbs, and digestive enzymes.
Q. Where can I buy Ota-isan in Japan?
OTC drugs such as Ota-isan S, Bunpo S, Ota-isan A, and Chewable NEO are sold at pharmacies and drugstores in Japan. Some Don Quijote stores carry them too, but the product range, prices, and stock vary by store.
Ota-isan NEXT and NEXT Tablets are designated quasi-drugs sold at convenience stores and elsewhere. Ota-isan Onaka Support is sold at FamilyMart in Japan.
Q. Can I buy Ota-isan tax-free in Japan?
Yes. You can get a tax exemption on Ota-isan by spending ¥5,500 or more (tax included) on the same day at the same tax-free registered store. You must present your original passport at checkout, and tax-free-packaged medicine must not be opened or used until you leave Japan.
※ The above applies under the system in effect through October 31, 2026. From November 1, 2026, it changes to a refund method where the consumption tax is returned after the goods are confirmed for export at departure.
Ota-isan products such as powder, tablet, and chewable each differ in ingredients and how to take them. Check the powder Ota-isan S, the portable Ota-isan Bunpo S, and the tablet Ota-isan A. Before buying, it's a good idea to compare the product name and size on the package, along with the selling price at each store.
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