Which Ohta's Isan Should I Buy in Japan?

If you search “Which Ohta’s Isan should I buy in Japan?”, the short answer is:

Do not choose only by the famous Ohta’s Isan name. Choose by symptom and form: powder, packet, tablet, chewable, or compact convenience-store type.

This article focuses on common Ohta’s Isan stomach-related products travelers may see in Japan. It is a label-reading guide, not a product recommendation or personal medical advice.

Table of Contents

Quick Answer: Which Ohta’s Isan Product Are You Looking At?
The Most Important Things First
Why There Are Different Ohta’s Isan Products
Quick Pharmacy Phrases
When to Choose Medical Care Instead
Bottom Line
Related Guides
References

Quick Answer: Which Ohta’s Isan Product Are You Looking At?

Product	Simple meaning	May suit someone who…
Ohta’s Isan S	Classic powder stomach medicine	wants the standard Ohta’s Isan-style option for drinking too much, heartburn, stomach discomfort, or stomach heaviness
Ohta’s Isan S packets	Same formula as Ohta’s Isan S, individually packed	wants the classic powder but easier to carry while traveling
Ohta’s Isan A tablets	Tablet type with digestive-support ingredients	wants a tablet option, especially after overeating or a heavy/fatty meal
Ohta Kampo Ichoyaku II	Kampo stomach medicine for stress-related or chronic weak-stomach patterns	has stomach discomfort that is not simply from overeating or drinking
Ohta’s Isan Chewable NEO	Water-free chewable for heartburn, bloating, and stomach discomfort	wants an adult chewable option that can be taken without water
Ohta’s Isan NEXT / NEXT tablets	Compact designated quasi-drug, often easier to buy casually	wants a small travel-sized option for mild discomfort after eating or drinking

Official product pages now show Ohta’s Isan S and Ohta’s Isan S packets. Older “Ohta’s Isan” and “Ohta’s Isan packet” pages note that manufacturing ended in September 2025, so check the exact package name if you see older information online.

The Most Important Things First

Before buying an Ohta’s Isan product in Japan, check these points:

Heartburn, sour stomach, stomach acid feeling: Ohta’s Isan S or Chewable NEO may be the first products to compare.
Stomach heaviness after a big or oily meal: Ohta’s Isan A tablets may be easier to understand.
Stress-related or chronic weak stomach: Ohta Kampo Ichoyaku II is the product to ask about, not the regular powder.
Need something portable: packets, Chewable NEO, or NEXT may be easier for travel.
Age matters: some products can be used by children, while Chewable NEO and NEXT products are for age 15 and older.
Do not combine several stomach medicines on your own. Ask pharmacy staff if you are already taking antacids, acid reducers, pain medicine, antibiotics, or regular prescriptions.

Why There Are Different Ohta’s Isan Products

Ohta’s Isan is a brand, not one single medicine.

The main differences are:

powder vs tablet vs chewable
antacid-type ingredients vs digestive enzymes vs Kampo formula
home-use can vs travel packets
OTC medicine vs designated quasi-drug
age range and how to take it

Ohta’s Isan S

Ohta’s Isan S is the current classic powder-style product. It is a general stomach medicine for symptoms such as drinking too much, heartburn, stomach discomfort, weak stomach, stomach heaviness, overeating, indigestion, excess stomach acid, nausea, vomiting, belching, and stomach fullness.

It contains stomachic herbal ingredients, antacid ingredients, and a digestive enzyme. Ingredient examples include cinnamon bark, fennel, nutmeg, clove, citrus peel, gentian, sodium bicarbonate, precipitated calcium carbonate, synthetic hydrotalcite, and biodiastase.

This may be worth asking about if you want the standard Ohta’s Isan-style powder and do not mind taking powder with water or warm water.

Ohta’s Isan S Packets

Ohta’s Isan S packets contain the same formula as Ohta’s Isan S, but each dose is individually packed.

This may be worth asking about if you want the classic powder but plan to carry it during travel, meals out, or a long sightseeing day.

The practical difference is convenience, not a different medicine concept.

Ohta’s Isan A Tablets

Ohta’s Isan A tablets are a tablet-type stomach medicine. They are especially positioned for stomach heaviness and overeating, including discomfort after fatty meals.

They include digestive-support ingredients such as lipase AP6, Prozyme 6, biodiastase 1000, and ursodeoxycholic acid, plus antacid ingredients and herbal oil ingredients.

This may be worth asking about if you want a tablet instead of powder, or if your main issue is “I ate too much” rather than a simple acid reflux feeling.

Ohta Kampo Ichoyaku II

Ohta Kampo Ichoyaku II is a Kampo-style stomach medicine. It is positioned for “stress stomach” patterns, nervous gastritis, chronic gastritis, and weak stomach patterns with symptoms such as stomach pain, heartburn, belching, stomach heaviness, appetite loss, nausea, or vomiting.

Its Kampo formula is based on Anchusan plus Poria. The listed crude drugs include Poria, cinnamon bark, Corydalis tuber, oyster shell, fennel, Amomum seed, licorice, and Alpinia officinarum rhizome.

This may be worth asking about if your stomach feels off from stress, tension, or a weak-stomach pattern, not just from drinking or overeating.

Ohta’s Isan Chewable NEO

Ohta’s Isan Chewable NEO is a chewable stomach medicine for age 15 and older. It can be chewed or dissolved in the mouth and does not require water.

It is focused on heartburn, bloating, stomach discomfort, stomach pain, excess stomach acid, stomach heaviness, drinking too much, nausea, belching, and vomiting.

Key ingredients include antacids such as magnesium hydroxide, magnesium carbonate, and precipitated calcium carbonate, plus dimethylpolysiloxane for gas/bloating.

This may be worth asking about if you want an adult water-free option for heartburn or bloating during travel.

Ohta’s Isan NEXT / NEXT Tablets

Ohta’s Isan NEXT and NEXT tablets are designated quasi-drugs, not the same category as Ohta’s Isan S. They are compact products for stomach discomfort and nausea from eating too much or drinking too much.

They contain stomachic herbal ingredients and ursodeoxycholic acid as a digestive-support ingredient. NEXT is powder; NEXT tablets are tablets.

This may be worth asking about if you see a small Ohta’s Isan product in a convenience-store setting and want a compact option for mild discomfort after food or alcohol.

If symptoms feel stronger, more unusual, or clearly acid-related, ask pharmacy staff whether an OTC medicine would be more appropriate.

Quick Pharmacy Phrases

You can show these phrases at a Japanese pharmacy:

English meaning	Japanese to show
Which Ohta’s Isan product is this?	これはどの太田胃散ですか？
Is this powder, tablets, or chewable?	これは粉ですか、錠剤ですか、チュアブルですか？
Is this for heartburn or stomach acid?	これは胸やけや胃酸に向いていますか？
Is this for stomach heaviness after eating too much?	これは食べすぎや胃もたれに向いていますか？
Can I take this without water?	これは水なしで飲めますか？
What age can use this?	これは何歳から使えますか？
I already take other medicine.	すでに他の薬を飲んでいます。
Should I see a doctor instead?	市販薬ではなく受診した方がよいですか？

For broader pharmacy phrases, see: Show This at a Japanese Pharmacy: OTC Medicine Questions in English and Japanese.

When to Choose Medical Care Instead

OTC stomach medicine is not the right answer for every stomach symptom.

Consider medical care if symptoms are severe, unusual, worsening, or keep coming back. This is especially important for strong chest pain, black stool, vomiting blood, trouble swallowing, unexplained weight loss, severe abdominal pain, repeated vomiting, dehydration, pregnancy, or symptoms in a young child.

If symptoms feel urgent in Japan, call 119.

If you are not sure how to find care, see: How to See a Doctor in Japan as a Traveler.

Bottom Line

Ohta’s Isan is not just one product in Japan.

For many travelers:

Ohta’s Isan S = classic powder for general stomach discomfort, heartburn, drinking, and stomach heaviness.
Ohta’s Isan S packets = same idea, easier to carry.
Ohta’s Isan A tablets = tablet option, especially after overeating or fatty meals.
Ohta Kampo Ichoyaku II = stress-related or chronic weak-stomach pattern.
Chewable NEO = adult water-free chewable for heartburn and bloating.
NEXT / NEXT tablets = compact designated quasi-drug for mild discomfort after food or alcohol.

The fastest way to choose is to tell pharmacy staff your main symptom: heartburn, stomach heaviness, overeating, drinking, bloating, or mukamuka nausea.

For medicine-type comparison, see: Antacid vs H2 Blocker vs PPI in Japan: How to Compare OTC Stomach Medicine Types.

For acid reflux symptoms, see: Heartburn Medicine in Japan: OTC Ingredients for Acid Reflux, Sour Stomach, and Mukamuka.

Related Guides

References

Ohta’s Isan Co., Ltd. Ohta’s Isan S product information. https://ohta-isan.co.jp/product/medicine/ohtaisan-s/
Ohta’s Isan Co., Ltd. Ohta’s Isan S packets product information. https://ohta-isan.co.jp/product/medicine/ohtaisanb-s/
Ohta’s Isan Co., Ltd. Ohta’s Isan A tablets product information. https://ohta-isan.co.jp/product/medicine/ohtaisana/
Ohta’s Isan Co., Ltd. Ohta Kampo Ichoyaku II product information. https://ohta-isan.co.jp/product/medicine/kanpo2/
Ohta’s Isan Co., Ltd. Ohta Kampo Ichoyaku II tablets product information. https://ohta-isan.co.jp/product/medicine/kanpo2j/
Ohta’s Isan Co., Ltd. Ohta’s Isan Chewable NEO product information. https://ohta-isan.co.jp/product/medicine/neo/
Ohta’s Isan Co., Ltd. Ohta’s Isan NEXT product information. https://ohta-isan.co.jp/product/quasi_medicine/ohtaisannext/
Ohta’s Isan Co., Ltd. Ohta’s Isan NEXT tablets product information. https://ohta-isan.co.jp/product/quasi_medicine/ohtaisannextj/