Stomach and Digestive Problems in Japan: OTC Medicine Ingredients and Safety Checks

Stomach and digestive symptoms are common while traveling or living in Japan. You may eat unfamiliar foods, walk more than usual, change your schedule, or feel stressed in a new environment.

Japanese drugstores and pharmacies sell many OTC medicines for stomach and digestive problems. However, the labels are usually in Japanese, and the same English phrase, such as “stomach pain,” can mean very different things.

This guide explains ingredient names you may see on Japanese OTC medicine labels. It does not recommend a specific product or tell you which medicine to take. Use ingredient names as label-reading clues, and ask pharmacy staff whether a product matches your symptoms and situation.

Some OTC medicines in Japan may require confirmation by a pharmacist or registered seller before purchase. Depending on the medicine, your age, symptoms, medical history, pregnancy status, or other medicines you take, the product may not be available or may not be appropriate.

If your symptoms are severe, unusual, getting worse, or not improving, consider medical care instead of trying to manage them with OTC medicine.

Quick Takeaway: What to Check First

Before buying stomach or digestive medicine in Japan, check these points first:

• Who will use the medicine: an adult, a child, an elderly person, or someone who is pregnant or breastfeeding?
• What is the main symptom: heartburn, stomach heaviness, cramping pain, diarrhea, motion sickness-related nausea, constipation, or bloating?
• Are symptoms severe, unusual, getting worse, or not improving?
• Are there warning signs such as fever, repeated vomiting, blood in stool, black stool, dehydration, or strong abdominal pain?
• What are the active ingredients, age limits, dose, and warnings on the label?
• Does the product require pharmacist or registered seller confirmation before purchase?

Do not choose an OTC medicine by ingredient name alone.

Before You Buy OTC Digestive Medicine in Japan

OTC digestive medicine is not one single category. A product for heartburn is different from a product for diarrhea, constipation, motion sickness, or cramping abdominal pain.

It is also important to remember that “stomach pain” can come from many causes. It may be related to acid reflux, overeating, intestinal cramps, constipation, infection, food poisoning, gallbladder problems, appendicitis, or other conditions.

When you speak with pharmacy staff, it helps to show or explain:

• your main symptom
• when it started
• who will use the medicine
• your age or the user’s age
• pregnancy or breastfeeding status
• allergies
• chronic conditions
• current medicines
• whether you have fever, vomiting, diarrhea, blood in stool, or severe pain

Pharmacy staff may recommend an OTC product, but they may also tell you to see a doctor instead.

Ingredient Names Are Label Clues, Not Recommendations

This article lists ingredient names because they can help you recognize what type of product you are looking at. They are not a shopping list.

For example, seeing famotidine on a label may tell you that the product is an acid-related medicine. Seeing loperamide may tell you that the product is a stronger antidiarrheal medicine. Seeing magnesium oxide may tell you that the product is a laxative-type product.

But the right choice depends on your symptoms, age, health conditions, allergies, and other medicines. Ask pharmacy staff whether the product type matches your situation.

Symptom and Ingredient Overview

Symptom pattern	Ingredient categories you may see	Important caution
Heartburn / acid reflux	Antacids, H2 blockers, PPI-type products	Famotidine and PPI products may require pharmacist involvement
Stomach heaviness / indigestion	Digestive enzymes, herbal stomachics, mucosal protectants	Not for strong or unclear abdominal pain
Cramping abdominal pain	Antispasmodic ingredients	Do not use as a default answer for abdominal pain
Diarrhea	Intestinal regulators, adsorbent/astringent ingredients, loperamide	Be strict with suspected food poisoning, fever, vomiting, or blood in stool
Motion sickness-related nausea	Motion sickness ingredients	Not for unexplained or repeated vomiting
Constipation / bloating	Laxatives, gas-related ingredients	Avoid repeated stimulant laxative use without advice
Severe or unclear abdominal pain	No ingredient focus	Consider medical care

1. Heartburn, Acid Reflux, or Sour Stomach

If your main symptom is heartburn, sour burps, acid reflux, or a burning feeling around the upper stomach or chest, you may see OTC products that focus on stomach acid.

Ingredient names you may see include:

• synthetic hydrotalcite
• magnesium aluminometasilicate
• dried aluminum hydroxide gel
• magnesium oxide or magnesium hydroxide, when used as antacid ingredients
• famotidine
• lansoprazole
• omeprazole
• rabeprazole sodium

These ingredients may appear in antacid products, H2 blocker products, or PPI-type products. They should not be treated as the answer for every type of upper abdominal pain.

Famotidine-containing OTC products are Class 1 OTC medicines in Japan, so pharmacist involvement is required. PPI-type products can be sold as guidance-required medicines, which also means pharmacist confirmation is important.

Ask pharmacy staff before choosing these products, especially if symptoms are frequent, severe, or different from usual.

Consider medical care if you have black stool, vomiting blood, chest pain, unexplained weight loss, difficulty swallowing, strong pain, or repeated symptoms.

2. Stomach Heaviness or Indigestion After Eating

If your stomach feels heavy after eating, or if you feel mild indigestion after overeating, you may see products with digestive enzymes, herbal stomachic ingredients, or stomach lining support ingredients.

Ingredient names you may see include:

• biodiastase
• diastase
• lipase
• pancreatin
• cinnamon bark
• gentian
• fennel
• clove
• ginger
• bitter orange peel
• atractylodes
• sucralfate hydrate
• sodium azulene sulfonate
• L-glutamine
• teprenone
• ursodeoxycholic acid

These ingredients may appear in products for mild stomach heaviness, indigestion, digestive support, or stomach lining support. They are not a general solution for all stomach pain.

If you have strong pain, repeated vomiting, black stool, fever, or symptoms that do not improve, do not keep trying different OTC products on your own. Ask pharmacy staff or consider medical care.

3. Cramping or Squeezing Abdominal Pain

Some people describe abdominal pain as cramping, squeezing, or coming in waves. In Japanese, this may be described as “sashikomi,” meaning a sharp or cramping abdominal pain.

Ingredient names you may see include:

• scopolamine butylbromide / hyoscine butylbromide
• Scopolia extract / Rohto extract

Rohto extract is an ingredient name. It does not mean the product is necessarily from the Rohto brand.

These are antispasmodic or anticholinergic-type ingredients. They may be used in products for stomach or intestinal cramps, but they are not a default answer for abdominal pain.

Ask pharmacy staff before using these products if the medicine is for an elderly person, if you are pregnant or breastfeeding, or if you have glaucoma, difficulty urinating, heart disease, or other medical conditions. Also ask if you take other medicines, including motion sickness medicine or other stomach medicine.

Consider medical care if pain is strong, unusual, getting worse, persistent, or accompanied by fever, vomiting, blood in stool, severe constipation, dehydration, or a hard or swollen abdomen.

4. Diarrhea

Diarrhea is one of the most important symptoms to handle carefully. Some diarrhea may be mild, but diarrhea can also happen with infection or food poisoning.

Ingredient names you may see include:

• bifidobacteria
• lactomin / lactic acid bacteria
• butyric acid bacteria
• natural aluminum silicate
• smectite
• albumin tannate
• loperamide hydrochloride

Intestinal regulator products may contain bifidobacteria, lactomin, lactic acid bacteria, or butyric acid bacteria. These products are usually meant to help regulate the intestinal environment, not to stop diarrhea immediately.

Some antidiarrheal products may contain adsorbent or astringent-type ingredients such as natural aluminum silicate, smectite, or albumin tannate. Albumin tannate may not be suitable for people with milk allergy. Aluminum-containing ingredients may also require caution for people with kidney disease or dialysis treatment.

Loperamide hydrochloride is a stronger antidiarrheal ingredient that slows intestinal movement. It should not be chosen casually, especially if infection or food poisoning is possible.

Do not simply try to stop diarrhea on your own if you have:

• suspicious food the previous day
• fever
• vomiting
• blood or mucus in stool
• strong abdominal pain
• dehydration
• several people becoming sick after the same meal

In these situations, ask pharmacy staff or consider medical care.

5. Motion Sickness-Related Nausea

For this article, nausea medicine mainly means motion sickness-related nausea, such as nausea during a car, bus, train, boat, or flight.

Ingredient names you may see include:

• meclizine hydrochloride
• scopolamine hydrobromide hydrate
• diphenhydramine salicylate

Some products may also contain supporting ingredients such as caffeine or pyridoxine hydrochloride, which is vitamin B6.

OTC motion sickness medicines are not the same as prescription antiemetics such as domperidone or metoclopramide. In Japan, medicines such as Nauzelin or Primperan are prescription medicines, not general OTC options for travelers to pick up at a drugstore.

Many motion sickness medicines can cause sleepiness, dry mouth, blurred vision, or difficulty urinating. Ask pharmacy staff before using them if you are elderly, pregnant, breastfeeding, have glaucoma, have difficulty urinating, have heart disease, or take cold medicine, allergy medicine, sleep aids, or another motion sickness medicine.

Consider medical care if vomiting is repeated, severe, unexplained, or accompanied by dehydration, fever, severe abdominal pain, severe headache, head injury, pregnancy, or suspected food poisoning.

6. Constipation and Bloating

Constipation and bloating are often discussed together, but constipation medicine and gas-related medicine are not the same.

Ingredient names you may see include:

• magnesium oxide
• sennosides / senna
• bisacodyl
• sodium picosulfate
• dimethylpolysiloxane / dimethicone

Magnesium oxide is an osmotic or saline-type laxative ingredient. Ask pharmacy staff before using it if you are elderly, have kidney disease, are on dialysis, have heart disease, or take other medicines.

Sennosides, senna, bisacodyl, and sodium picosulfate are stimulant laxative-type ingredients. They may cause abdominal cramping or diarrhea.

Stimulant laxatives may become less effective if used too often, and repeated use can make it harder to have bowel movements without them. Do not use them continuously unless a healthcare professional tells you to.

Dimethylpolysiloxane, also called dimethicone, is different from a laxative. It may appear in products for gas-related fullness or bloating, not for severe or unexplained abdominal pain.

Consider medical care if you have strong abdominal pain, repeated vomiting, fever, blood in stool, black stool, a hard or swollen abdomen, sudden severe constipation, or inability to pass stool or gas.

7. Severe or Unclear Abdominal Pain: When Not to Self-Treat

Severe or unclear abdominal pain should not be treated as a simple OTC medicine problem.

Do not automatically use pain relievers, antidiarrheal medicine, laxatives, or stomach medicine if the cause of abdominal pain is unclear.

Abdominal pain can have many causes. OTC medicine may hide symptoms or delay medical care.

Consider medical care if abdominal pain is:

• strong
• sudden
• getting worse
• different from usual
• accompanied by fever
• accompanied by repeated vomiting
• accompanied by blood in stool or black stool
• accompanied by severe diarrhea or dehydration
• accompanied by faintness, chest pain, or shortness of breath
• associated with a hard or swollen abdomen
• associated with inability to pass stool or gas

Be especially careful if the person is a child, elderly, pregnant, has a chronic disease, recently had surgery, or takes prescription medicines.

Show This for Stomach or Digestive Symptoms

You can show this card at a Japanese pharmacy. Choose the lines that match your situation.

English meaning	Japanese to show
I have stomach or digestive symptoms.	胃腸の症状があります。
I have heartburn or acid reflux.	胸やけや胃酸が上がる感じがあります。
My stomach feels heavy after eating.	食後に胃もたれがあります。
I have cramping abdominal pain.	差し込むような腹痛があります。
I have diarrhea.	下痢があります。
I have nausea from motion sickness.	乗り物酔いによる吐き気があります。
I have constipation or bloating.	便秘またはお腹の張りがあります。
I ate something suspicious yesterday.	昨日、食中毒が心配な食事をしました。
I also have fever or vomiting.	発熱または嘔吐もあります。
Should I see a doctor instead of using OTC medicine?	市販薬ではなく、受診した方がよいですか？

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

When to Ask Pharmacy Staff

Ask pharmacy staff before buying OTC digestive medicine if:

• the medicine is for a child, elderly person, or pregnant or breastfeeding person
• you have allergies
• you have kidney disease, heart disease, glaucoma, difficulty urinating, or another chronic condition
• you take prescription medicines or other OTC medicines
• symptoms are severe, unusual, getting worse, or not improving
• you are not sure which symptom category matches your situation

Some OTC medicines may not be available without pharmacist or registered seller confirmation. Pharmacy staff may also recommend seeing a doctor instead of buying OTC medicine.

FAQ

Can I buy stomach medicine at a drugstore in Japan?

Yes, many Japanese drugstores sell OTC stomach and digestive medicines. However, some products require pharmacist or registered seller confirmation, and some may not be appropriate depending on your symptoms or health conditions.

What OTC ingredients should I look for for heartburn in Japan?

For heartburn or acid reflux, you may see antacid ingredients, famotidine, or PPI-type ingredients such as lansoprazole, omeprazole, or rabeprazole sodium. Do not choose by ingredient name alone. Ask pharmacy staff whether the product matches your symptoms.

Can I use loperamide for diarrhea while traveling in Japan?

Do not use loperamide casually. If diarrhea may be related to food poisoning or infection, especially with fever, vomiting, blood in stool, strong abdominal pain, or dehydration, ask pharmacy staff or seek medical care.

Is motion sickness medicine the same as nausea medicine?

No. OTC motion sickness medicines are mainly for motion sickness-related nausea. They are not the same as prescription antiemetics, and they are not meant for repeated, severe, or unexplained vomiting.

What should I check before buying constipation medicine in Japan?

Check the active ingredient, age limit, dose, and warnings. Be careful with magnesium oxide if you have kidney disease or are on dialysis. Be careful with repeated stimulant laxative use, such as products containing senna, sennosides, bisacodyl, or sodium picosulfate.

When should I see a doctor for stomach pain in Japan?

Consider medical care if abdominal pain is strong, sudden, getting worse, unusual, or comes with fever, repeated vomiting, blood in stool, black stool, dehydration, a hard or swollen abdomen, or inability to pass stool or gas.

References

• Ministry of Health, Labour and Welfare. Information on Japan’s medicine sales system.
• Pharmaceuticals and Medical Devices Agency (PMDA). OTC medicine package insert search.
• Pharmaceuticals and Medical Devices Agency (PMDA). Safety information regarding drugs.
• Japan National Tourism Organization (JNTO). Guide for when you are feeling ill in Japan.