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.
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.
About the Author
Sakura is a licensed Japanese pharmacist with 13+ years of clinical experience: 2 years as a hospital pharmacist and 11 years in dispensing pharmacies — including a community-based pharmacy, a pediatric-clinic-attached pharmacy, and home-care practice. She continues to work as a dispensing pharmacist, and has been writing healthcare content as a side project for about 2 years. AskJapanPharmacist is her newest project, launched recently to share Japanese OTC and pharmacy knowledge with international readers.
Editorial workflow
All articles are written and reviewed by Sakura, a licensed pharmacist in Japan. English and Simplified Chinese translations are produced with AI-assisted tooling and reviewed by the lead pharmacist before publication. Fact-checking is supported by AI-assisted regulatory review (Japanese Pharmaceutical Affairs Act / PMDA references), with final responsibility resting with the lead pharmacist.