Bringing Thyroid Medication to Japan: What You Need to Know

Bringing thyroid medication to Japan is legal and, for most travelers, requires no special paperwork: it's an ordinary prescription drug, so up to a 1-month supply is allowed in with no certificate, with a certificate needed beyond that. Levothyroxine, sold under brand names including Synthroid, isn't controlled in Japan — it doesn't appear on any narcotics or psychotropic list. The real planning problem is different: thyroid medication is a daily, no-gaps drug, a foreign prescription cannot be refilled at a Japanese pharmacy, and you'll need to see a doctor here before your supply runs out. Line that up early and the import rules take care of themselves.

Japan sorts personal medication imports by category, not by drug name, and thyroid hormone replacement falls into the plainest one: ordinary prescription drugs, capped at a 1-month supply with no certificate required. That covers a short trip or the first weeks of a move. Even within that allowance, carry a copy of your prescription and a doctor's letter alongside the medication — customs can ask, and having both ready avoids a delay at the counter.

If you're relocating and want to bring more than a month's worth to bridge the gap while you find a doctor here, you'll need the 輸入確認書 (Yunyu Kakunin-sho), still widely called 薬監証明 (Yakkan Shoumei), issued by MHLW. Apply through the online portal at least 14 days before arrival — processing typically takes about 2-3 business days once complete, but build in extra time around Golden Week, Obon, or New Year. At customs, keep the certificate with your prescription and doctor's letter in hand luggage and use the red, declare channel.

Getting the medication through customs is the easy part. The harder problem is what happens on day 31, because a prescription written outside Japan cannot be filled at a Japanese pharmacy — pharmacists here dispense against a Japanese 処方箋 (shohosen) only, and they cannot prescribe. Keeping your dose uninterrupted means being seen by a doctor in Japan before you need the next refill, not after.

The single most useful thing to carry for that first appointment is a doctor's letter stating your medication by its INN (international nonproprietary name) — levothyroxine — rather than only a brand name like Synthroid. Brand names vary by country, but the INN and your dose are unambiguous anywhere. Bring your dosage, how long you've been on it, and recent lab values if you have them; a first visit typically includes a written questionnaire (問診票, monshinhyo) before a prescription is issued.

For the general rules on carrying any prescription medication into Japan, see bringing prescription medication to Japan. If your supply is already close to running out, running out of medication in Japan walks through that visit, and foreign prescription in Japan covers why a script from home can't simply be handed to a pharmacist here. For the wider system — insurance, registering with a clinic, pharmacies versus drugstores — the health guide and moving to Japan guide go further than this page needs to.