When buying pain or fever medicine in Japan, two ingredient names often matter:
- loxoprofen sodium hydrate
- acetaminophen, also called paracetamol
They can both be used for pain or fever in some OTC products, but they are not the same. The most important differences are anti-inflammatory effect, stomach/kidney/asthma cautions, pharmacist involvement, and age limits.
This article is general information for travelers and residents. It is not a diagnosis or a personal medicine recommendation.
Quick Summary
For a quick comparison:
- Loxoprofen: NSAID, anti-inflammatory, pharmacist involvement in Japan, not for under 15 in OTC oral pain/fever products.
- Acetaminophen/paracetamol: pain and fever medicine, little practical anti-inflammatory effect, overdose and duplicate cold medicine risk, child-specific products exist but adult products are not for children.
The safest next step is simple: check the active ingredient, age limit, warnings, and other medicines already taken. If anything is unclear, ask pharmacy staff before using it.
Quick Answer
| Question | Loxoprofen | Acetaminophen / Paracetamol |
| What type of medicine is it? | NSAID-type pain and fever medicine | Pain and fever medicine, not an NSAID |
| Anti-inflammatory effect? | Yes, it is used as an anti-inflammatory pain reliever | Little or no practical anti-inflammatory effect |
| Common Japan OTC example | Loxonin S series, as an example, not a recommendation | Tylenol A and other acetaminophen products, as examples, not recommendations |
| Can children use it? | OTC oral loxoprofen products for pain/fever are generally not for people under 15 | Some child-specific acetaminophen products exist, but adult products such as Tylenol A are not for under 15 |
| Pharmacist involvement? | Oral OTC loxoprofen is a Class 1 OTC medicine in Japan and requires pharmacist involvement | Depends on product; still ask pharmacy staff if unsure |
| Main cautions | Stomach/duodenal ulcer, kidney disease, heart disease, NSAID-triggered asthma, late pregnancy, dehydration, other NSAIDs | Liver disease, heavy alcohol use, overdose risk, duplicate cold medicines |
If the medicine is for a child, pregnant person, elderly person, or someone with chronic disease, do not choose only by ingredient name. Ask pharmacy staff.
Loxoprofen: Anti-Inflammatory, but More Restrictions
Loxoprofen is an NSAID. NSAIDs can reduce pain, fever, and inflammation by affecting prostaglandin-related pathways.
In Japan, oral OTC loxoprofen products for pain or fever, such as products in the Loxonin S series, are Class 1 OTC medicines. A pharmacist must be involved in the sale. A drugstore may be open, but loxoprofen may not be available if the pharmacist counter is closed.
Loxoprofen may be considered when inflammation-related pain is part of the problem, such as some joint pain, muscle pain, toothache, menstrual pain, or injury-related pain. But this does not mean it is right for everyone.
Ask pharmacy staff before using loxoprofen if you have:
- stomach or duodenal ulcer
- kidney disease
- liver disease
- heart disease
- asthma triggered by pain relievers or cold medicine
- pregnancy or possible pregnancy
- dehydration, repeated vomiting, or possible heat illness
- blood thinner use or other regular medicines
- use of another NSAID or pain reliever today
OTC oral loxoprofen products for pain or fever should not be used by people under 15.
Acetaminophen: Pain and Fever, but Not Anti-Inflammatory
Acetaminophen is also called paracetamol. It is used for pain and fever, but it is not an NSAID and does not have the same anti-inflammatory effect as loxoprofen.
This can make acetaminophen easier to consider in some situations where NSAIDs may be a concern, but it still has important cautions.
Ask pharmacy staff before using acetaminophen if you have:
- liver disease
- heavy alcohol use
- kidney disease, heart disease, or other chronic disease
- pregnancy or breastfeeding
- regular medicines
- already taken cold medicine or another pain/fever medicine
Many cold medicines can contain acetaminophen. Taking a cold medicine plus another acetaminophen product can accidentally exceed the safe amount.
For children, the key point is product selection. Some acetaminophen products are made for children, but adult products are not automatically safe for children. Tylenol A, for example, is for adults 15 and older. For a child, use only a product that clearly matches the child’s age and situation, and ask pharmacy staff.
Do Not Use Adult Pain Medicine for Children by Guessing
This is one of the most important checks.
If the person is under 15:
- do not use OTC oral loxoprofen for pain or fever
- do not use adult acetaminophen products just because the ingredient sounds familiar
- ask pharmacy staff for a child-appropriate product
- check age, weight, dose, and dosing interval
- consider medical care if fever or pain is strong, unusual, or worsening
Children’s fever or pain can need different decisions from adult symptoms.
Quick Label Checklist
Before using either ingredient, check:
- Active ingredient name
- Age limit
- Dose per use
- Maximum daily dose
- Dosing interval
- Whether the product is for fever, pain, cold symptoms, or several symptoms
- Whether another medicine already contains the same or similar ingredient
- Warnings for stomach ulcer, asthma, liver disease, kidney disease, pregnancy, alcohol, dehydration, or other medicines
If you are unsure, show the package to pharmacy staff before taking it.
What to Ask at a Japanese Pharmacy
You can show these phrases:
| English meaning | Japanese to show |
| Does this contain loxoprofen? | これはロキソプロフェンを含んでいますか？ |
| Does this contain acetaminophen? | これはアセトアミノフェンを含んでいますか？ |
| Is this an anti-inflammatory medicine? | これは炎症を抑える薬ですか？ |
| Is this safe for someone under 15? | 15歳未満でも使えますか？ |
| I already took cold medicine. | すでに風邪薬を飲みました。 |
| Please check whether the ingredients overlap. | 成分が重なっていないか確認してください。 |
| I have asthma / stomach ulcer / liver disease / kidney disease. | 喘息／胃潰瘍／肝臓病／腎臓病があります。 |
| Should I see a doctor instead? | 薬ではなく受診した方がよいですか？ |
For a broader phrase card, see: Show This at a Japanese Pharmacy: OTC Medicine Questions in English and Japanese.
When to Seek Medical Care
Do not rely only on OTC medicine if symptoms are severe, unusual, getting worse, or not improving.
Consider medical care for:
- severe or sudden pain
- chest pain, trouble breathing, weakness, numbness, or confusion
- high or persistent fever
- stiff neck, rash, repeated vomiting, or dehydration
- severe abdominal pain
- black stool, bloody stool, or vomiting blood
- pain after a major injury
- symptoms in a child, elderly person, pregnant person, or medically fragile person
- possible heat illness
If symptoms feel severe or urgent in Japan, call 119.
If you are not sure how to find medical care in Japan, see: How to See a Doctor in Japan as a Traveler.
Related Guides
- Fever in Japan: How to Choose OTC Medicine Safely as a Traveler or Resident
- Headache Medicine in Japan: OTC Pain Relievers and Safety Checks
- Heat Illness in Japan: What Travelers Should Check Before Taking Fever Medicine
- Drugstore Basics in Japan: How to Buy OTC Medicine Safely
- How to See a Doctor in Japan as a Traveler
References
- Pharmaceuticals and Medical Devices Agency (PMDA). OTC medicine package insert search. https://www.pmda.go.jp/PmdaSearch/otcSearch/
- Daiichi Sankyo Healthcare. Loxonin S product information. https://www.daiichisankyo-hc.co.jp/products/details/loxonin-s/
- Tylenol Japan. Tylenol A product information. https://www.tylenol.jp/products-tylenol
- Ministry of Health, Labour and Welfare. Information on the Japanese OTC medicine sales system. https://www.mhlw.go.jp/stf/seisakunitsuite/bunya/0000092787.html
- NHS. Ibuprofen for adults. https://www.nhs.uk/medicines/ibuprofen-for-adults/
- NHS. Paracetamol for adults. https://www.nhs.uk/medicines/paracetamol-for-adults/
