Metformin in Japan: Brands, Yakkan Shoumei and Pharmacies

Metformin is not a controlled substance in Japan, but import quantity limits and prescription rules apply. Here is what to prepare before you travel.

Quick reference

Drug class: Biguanide antihyperglycaemic
Controlled substance: No — not scheduled under Japan's Narcotics and Psychotropics Control Act or Stimulants Control Act
Prescription required: Yes — metformin is a prescription-only medicine (処方箋医薬品) in Japan
Available locally: Yes — available under brand names Melbin, Metgluco, and Glycoran, plus multiple generics including Metformin HCl MT 'Towa'
Storage: Room temperature 20°C to 25°C (68°F to 77°F); keep dry and away from direct light; no refrigeration required
Max supply to carry: Up to 1 month's supply of prescription medication without a Yunyu Kakunin-sho import certificate; beyond 1 month requires the certificate obtained in advance
Key document: Doctor's letter on clinic letterhead stating your full name, medication name (metformin hydrochloride), dose, frequency, quantity carried, and your diagnosis; no notarisation required for a standard 1-month supply
Emergency alternative: Visit an internal medicine clinic (内科, naika) or international hospital emergency department and request a local prescription for metformin hydrochloride — it is widely stocked at Japanese pharmacies

Taking Metformin to Japan

Metformin is not a controlled or prohibited substance in Japan, so it will not trigger the strict import restrictions that apply to stimulants or opioids. The key rule to understand is the quantity limit: you may bring up to one month's supply of a prescription medicine without any advance permit, but anything beyond that requires a Yunyu Kakunin-sho import certificate obtained before you depart. Metformin is available locally under different brand names, but you will need a Japanese prescription to obtain it, which adds time and cost to an already stressful situation. Bring your full supply and document it properly.

Medical disclaimer: This guide is for informational purposes only and does not constitute medical advice. Always consult your prescribing doctor before travelling with medication, particularly regarding supply quantities, storage requirements, and import documentation. Regulations change — verify current rules with Japan's Ministry of Health, Labour and Welfare before you travel.

Before you travel

Documentation for travelling to Japan with Metformin

Japan regulates medication imports under the Pharmaceutical Affairs Law and the Customs Law, administered by the Ministry of Health, Labour and Welfare (MHLW). For a standard supply of up to one month, you do not need an import certificate, but carrying a doctor's letter and a copy of your prescription is strongly recommended in case customs officers ask questions. If you are travelling for more than one month and need to carry a larger supply, you must apply for a Yunyu Kakunin-sho from the Regional Bureau of Health and Welfare nearest to your arrival airport at least two weeks before you travel. Applications to the wrong regional bureau will delay or invalidate your certificate, so confirm which bureau covers your airport of entry.

Pre-travel metformin paperwork timeline

T-30 days
Confirm your dosing and trip length. Metformin is not a controlled drug in Japan, but supply over 1 month's personal use needs a Yakkan Shoumei (Import Confirmation Certificate).
T-14 days
If you're carrying more than 30 days' supply, apply for a Yakkan Shoumei via the MHLW Pharmaceutical and Medical Devices Bureau. Most travellers carrying ≤30 days do not need one.Yakkan Shoumei
Free to apply; processing typically 5–10 working days.
T-7 days
Get a prescriber letter naming metformin (INN), brand, dose, daily total, and trip-length quantity. A Japanese translation is appreciated by customs but not legally required for metformin.
T-1 day
Pack metformin in pharmacy-labelled original packaging in carry-on. Print all documents — Japanese customs prefers paper over phone screens.
T-0 (border)
If you have a Yakkan Shoumei, declare it proactively at customs. Otherwise, no declaration is needed for ≤30-day personal supply.

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What your doctor's letter must include

Full legal name as it appears on your passport. Medication name: metformin hydrochloride (INN) and the brand name on your packaging. Dose and frequency. Total quantity carried, expressed in number of tablets and days' supply. Your diagnosis (a single word or brief phrase is sufficient — e.g. 'diabetes'). Doctor's full name, registration or licence number, and signature. Clinic or hospital letterhead with contact details. A translation into Japanese is not legally required for a standard 1-month supply, but adding a simple Japanese note ('メトホルミン, 1ヶ月分') can speed up any customs exchange.

If your trip exceeds one month and you need the Yunyu Kakunin-sho, submit your application to the relevant Regional Bureau of Health and Welfare at least 14 days before departure. The certificate cannot be issued on arrival — customs officers do not grant on-the-spot exceptions. Keep a digital copy stored in your phone and email, alongside a physical copy with your medication.^[1]

How much Metformin to bring

Without a Yunyu Kakunin-sho, you are limited to a one-month supply of prescription medication. For trips of up to one month, bring exactly what you need plus a 20–30% buffer to cover lost tablets, delays, or dose adjustments. For longer stays, apply for the Yunyu Kakunin-sho to cover your full intended supply. Overseas prescriptions are not honoured in Japan, meaning you cannot simply present a foreign prescription at a local pharmacy and receive a refill. Getting a local prescription requires visiting a doctor, which takes time and adds cost, particularly if you need an English-speaking clinic.

Split your supply

Carry your main supply in hand luggage and a backup amount in checked luggage. If one bag is lost or delayed, you still have medication to continue your schedule. Keep both portions in original blister packs or manufacturer packaging with the pharmacy label visible — loose tablets in an unmarked container can raise questions at customs.

Packing and storing Metformin for travel

Metformin does not require refrigeration. Per FDA-approved prescribing information, it should be stored at a controlled room temperature of 20°C to 25°C (68°F to 77°F), with brief excursions permitted between 15°C and 30°C (59°F to 86°F). Keep tablets in a tightly closed, moisture-resistant container — humidity is the primary risk in Japan, particularly during the rainy season (June to July) and the hot, humid summer months. Do not store metformin in a bathroom or in a bag compartment that sits in direct sunlight during long transit days. If your bag goes into a hot aircraft hold or a parked vehicle in summer, check your tablets for discolouration, crumbling, or unusual odour before taking them.

At the airport and border

Airport security with Metformin

Metformin tablets are solid oral medication and do not require any special declaration at airport security screening. They are not subject to liquid or gel restrictions and do not trigger the 100ml liquid rule. Keep your medication in your hand luggage in its original packaging so that security staff can identify it quickly if your bag is screened. There is no requirement to remove medication from your bag during X-ray, but having your doctor's letter accessible in a side pocket avoids delays if you are asked to verify the contents.

Customs and medication import rules for Japan

Japan Customs enforces medication import rules under the Pharmaceutical Affairs Law and the Customs Law. Metformin is not a prohibited or controlled substance, so it does not require advance declaration in the Red Channel unless you are carrying a quantity that exceeds the one-month prescription limit.. If you hold a Yunyu Kakunin-sho for a larger supply, you must present it to the customs officer on arrival — this certificate must have been obtained before travel and cannot be arranged at the border.. If a customs officer questions your medication, present your doctor's letter and prescription copy calmly. Keep your medication in its original packaging with the pharmacy label intact to help officers verify the contents quickly.^[2]

Keep metformin in its original packaging

Removing metformin from its blister pack or original bottle and placing it in an unlabelled container is one of the most common reasons travellers face additional questioning at Japanese customs. Japanese customs officers are trained to cross-check the physical medication against the label and packaging photo on file. Keep every tablet in the original pack, with the pharmacy label showing your name, prescriber details, and dispensing date.

While in country

Metformin availability in Japan

Metformin brands available in Japan

Brand	Manufacturer	Formulation	Approved indication	Supply
Metgluco	Sumitomo Pharma	Immediate-release tablet (250 mg, 500 mg)	Type 2 diabetes	Most common Japanese metformin brand; reliably stocked
Metformin (generic)	Multiple — Sawai, Towa, Nichi-Iko	Immediate-release tablet (250 mg, 500 mg)	Type 2 diabetes	Widely stocked; cheapest option
Metact	Takeda	Combination tablet (metformin + pioglitazone)	Type 2 diabetes — combination therapy only	Available; for patients already on combo therapy
Metformin XR (extended-release)	Not registered	—	—	Not sold in Japan. Travellers on XR formulations should bring their full trip supply or ask their prescriber about switching to twice-daily IR for the trip.

Glucophage (Merck's global metformin brand) is not sold in Japan. Travellers on Glucophage will be dispensed Metgluco or generic metformin if they need a local refill.

Metformin hydrochloride is available in Japan under brand names including Melbin (the original Japanese brand, launched in 1961), Metgluco (approved in 2010, equivalent to Glucophage), and Glycoran, alongside a wide range of generics such as Metformin HCl MT 'Towa'. Metformin is a prescription-only medicine in Japan (処方箋医薬品, shohosen iyakuhin) — you cannot buy it over the counter at a pharmacy without a Japanese prescription. A local prescription requires a visit to an internal medicine clinic (内科, naika) or hospital. Without Japanese national health insurance, expect to pay between ¥5,000 and ¥20,000 (~$33–$133 / ~€30–€122) for a first consultation at a private or foreigner-friendly clinic, depending on whether additional tests are required.^[3]

Finding a doctor who can prescribe Metformin in Japan

Internal medicine clinics (内科) can prescribe metformin. In Tokyo, English-speaking options include St. Luke's International Hospital (Tsukiji), Tokyo Midtown Medical Clinic (Roppongi), and International Health Care Clinic (Shinbashi). The AMDA International Medical Information Center provides free telephone medical advice and can direct you to appropriate clinics — reachable in English. Telemedicine services such as CLINIC FOR offer English-language online consultations for visitors and can issue prescriptions with same-day medication delivery within Tokyo's 23 wards. Without Japanese health insurance, a first consultation at a standard clinic costs around ¥5,000–¥20,000 (~$33–$133 / ~€30–€122); English-speaking international clinics typically sit at the higher end of this range.^[4]

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Storing Metformin while in Japan

Metformin does not need refrigeration and is stable at controlled room temperature up to 25°C (77°F). Tokyo's summer (July to September) regularly exceeds 30°C outdoors, and humidity is high — avoid leaving your medication in a bag left in direct sunlight, a parked vehicle, or on a windowsill. Most Japanese hotel rooms maintain air conditioning at 25°C or below, making the bedside drawer a suitable storage spot. During the rainy season (tsuyu, roughly mid-June to mid-July), humidity can accelerate tablet degradation, so keep metformin in its original sealed blister pack or a moisture-resistant container rather than a pill organiser. If you notice any tablets have changed colour, crumbled, or developed an unusual smell, do not take them — contact a clinic or pharmacy for a replacement.

Emergencies

What to do if something goes wrong with your Metformin in Japan

If your metformin is lost or stolen, report the loss to the nearest police box (koban, 交番) and obtain a written incident report — your travel insurer will require this to cover a replacement prescription. Take the police report to an internal medicine clinic (内科) and request an emergency prescription; explain that your medication was lost and show any documentation you have, including your Nomedic IPS record or your doctor's letter.

If you run out of metformin, metformin hydrochloride is widely stocked at Japanese pharmacies under the brand names Melbin, Metgluco, and Glycoran, as well as multiple generics.. You will need a prescription from a Japanese doctor to obtain it — pharmacies cannot dispense prescription medicines without one. Visit the nearest naika clinic, present your IPS record or doctor's letter, and request a short-term supply. Carry your Nomedic IPS on your phone so the prescribing doctor can immediately confirm your medication name, dose, and frequency in a format any clinician can read.

Key phrases in Japanese

I take metformin: 'Metformin wo nonde imasu' (メトホルミンを飲んでいます). I need my medication: 'Kusuri ga hitsuyou desu' (薬が必要です). Please call a doctor: 'Isha wo yonde kudasai' (医者を呼んでください). Where is the nearest pharmacy?: 'Chikaku no yakkyoku wa doko desu ka?' (近くの薬局はどこですか？). I have diabetes: 'Tounyo-byo desu' (糖尿病です).

For any medical emergency in Japan, call 119 for an ambulance — ambulance transport is free of charge, though subsequent medical care is billed separately.. Police can be reached on 110. If you are in Tokyo and need help locating an English-speaking clinic, the Tokyo Metropolitan Health and Medical Information Center (Himawari) is reachable on 03-5285-8181 and provides guidance in English.^[5]

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Frequently asked questions

Can I bring Metformin into Japan?

Yes. Metformin is not a controlled or prohibited substance in Japan. You may bring up to one month's supply without an import certificate.. If you need more than one month's supply, apply for a Yunyu Kakunin-sho from the relevant Regional Bureau of Health and Welfare at least 14 days before you travel. Keep your medication in its original packaging with a doctor's letter.

Is Metformin available in Japanese pharmacies?

Yes, metformin hydrochloride is widely available at Japanese pharmacies under brand names including Melbin, Metgluco, and Glycoran, plus numerous generics.. However, it is a prescription-only medicine in Japan — you cannot purchase it without a Japanese prescription, which requires a consultation with a local doctor.^[6]

Do I need a doctor's letter to fly with Metformin?

A doctor's letter is not a legal requirement for a standard one-month supply of metformin entering Japan, but it is strongly recommended. If customs officers question your medication, a letter on clinic letterhead confirming your name, medication, dose, and diagnosis resolves the situation immediately. For supplies exceeding one month, a Yunyu Kakunin-sho import certificate is required and must be obtained before travel.

What if I run out of Metformin in Japan?

Visit an internal medicine clinic (内科, naika) and request a prescription for metformin hydrochloride. Present your Nomedic IPS or any documentation confirming your current dose. Once you have a prescription, any pharmacy (薬局, yakkyoku) can dispense the local equivalent. Without Japanese health insurance, expect to pay around ¥5,000–¥20,000 (~$33–$133 / ~€30–€122) for the consultation.

Does Japan's rainy season or summer heat affect Metformin storage?

Metformin is stable at room temperature up to 25°C (77°F) and tolerates brief excursions up to 30°C (86°F).. In Japan's humid summer and rainy season, the main risk is moisture rather than heat — keep tablets sealed in their original blister pack inside a cool, dry spot such as an air-conditioned hotel room. Avoid storing them in bathroom bags or on windowsills exposed to direct sun.

Can I use a foreign prescription at a Japanese pharmacy to get Metformin?

No. Overseas prescriptions are not legally honoured at Japanese pharmacies.. To obtain a local supply you must first consult a Japanese-registered doctor, who will issue a Japanese prescription. International clinics in major cities such as Tokyo, Osaka, and Kyoto can do this in English, often on the same day.