OTC Medicines at Japanese Pharmacies
Japanese pharmacies carry effective diarrhea remedies readily available without a prescription.
Seirogan (正露丸) — the classic Japanese anti-diarrhea remedy. Wood creosote-based, it has been used in Japan for over a century. Effective for mild food-related diarrhea.
Stoppa (ストッパ) and Imodium (available at large pharmacies) — loperamide-based medications that slow intestinal movement. Effective for watery, non-infectious diarrhea. Do not use if you have bloody diarrhea or high fever.
Wakamoto and BIO-THREE — probiotic-based intestinal regulators. Good for mild upset stomach and recovery phase.
Oral rehydration salts (OS-1) — critical for preventing dehydration. Available at pharmacies and some convenience stores. Far superior to plain water for rehydration.
Charcoal tablets — help absorb toxins in the gut. Available at most pharmacies.
Avoid spicy food, dairy, caffeine, and alcohol until symptoms resolve. Stick to rice (gohan/お米), toast, bananas, and boiled vegetables — the BRAT diet works well in Japan too.
Finding a Doctor in Japan
If you need medical care, visit an internal medicine clinic (内科, *naika*). Clinics specializing in gastroenterology (消化器内科, *shōkaki naika*) can handle more complex cases.
Translation apps and devices may not convey medical nuances accurately. We strongly recommend clinics with English-speaking staff. Search for English-capable internal medicine clinics using Traveler's Hospital hospital search.
Estimated Costs
Useful Japanese Phrases for Your Doctor Visit
Internal Links
For English-speaking internal medicine clinics, use Traveler's Hospital hospital search. If diarrhea is accompanied by vomiting you cannot control, see our nausea and vomiting guide.
FAQ
Q: Is tap water safe to drink in Japan?
A: Yes. Japan's tap water is among the cleanest in the world and is safe to drink everywhere. Diarrhea is rarely caused by tap water in Japan.
Q: Can I buy Imodium (loperamide) in Japan?
A: Loperamide is available at larger pharmacies under the brand name Imodium or similar generics. Ask the pharmacist by showing "loperamide" (ロペラミド) on your phone. Do not use it if you have bloody stools or high fever.
Q: Should I eat if I have diarrhea?
A: Yes, but keep it simple. Plain white rice (okayu/お粥, Japanese rice porridge) is ideal and widely available at convenience stores and restaurants. Avoid fatty, spicy, or sugary foods.
Q: What is OS-1 and where can I get it?
A: OS-1 is Japan's leading oral rehydration drink, balanced with the right ratio of sugar and electrolytes to replace what diarrhea removes. It is available at pharmacies and some 7-Eleven and FamilyMart stores, typically in the medical/pharmacy section.
Q: Do Japanese clinics do stool tests?
A: Yes. If your diarrhea is severe or prolonged, the doctor will likely request a stool sample (便培養検査) to identify bacterial infections. Results typically take 2–3 days, so initial treatment is usually empirical.
Q: Will Japanese doctors prescribe antibiotics?
A: Antibiotics are prescribed conservatively in Japan. They may be prescribed for confirmed bacterial infections like Campylobacter or Salmonella but are not given for viral gastroenteritis. Self-medicating with antibiotics you brought from home is not recommended without medical advice.