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painkillerOTCLoxonin

Today's OTC Spotlight: Loxonin S

A pharmacist's quick guide to Loxonin S — one of the most popular pain relievers in Japan — including how it works, who it's for, and precautions.

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Japanese Licensed Pharmacist
Published on 2026-04-18

Loxonin S (ロキソニンS) is one of the most widely used over-the-counter painkillers in Japan. If you walk into any drugstore and ask for something strong for a headache or menstrual pain, a pharmacist will often suggest this product.

What's in it?

The active ingredient is loxoprofen sodium (ロキソプロフェンナトリウム), a non-steroidal anti-inflammatory drug (NSAID). It is similar in class to ibuprofen but tends to act quickly.

What it's used for

  • Headache
  • Menstrual pain
  • Toothache
  • Muscle and joint pain
  • Fever associated with a cold

Who should be careful

  • People with a history of stomach ulcers
  • People with asthma triggered by painkillers
  • Pregnant women (especially in late pregnancy) — do not use
  • Children under 15 — do not use

How to ask for it in a pharmacy

You can simply say: "Loxonin S, kudasai." (ロキソニンS、ください。) In Japan, this product is sold as a Class 1 OTC (第1類医薬品), which means a pharmacist must hand it to you directly after a short check.

Medical disclaimer: This article is general information, not a prescription. If pain persists more than a few days, please see a doctor.