Loxonin S (ロキソニンS): ingredients, dose and warnings in English

Loxonin S (ロキソニンS) is sold in Japan as a class 1 medicine: the box reads 第1類医薬品. In 1 tablet: Loxoprofen Sodium Hydrate 68.1 mg. The package insert sets the adult dose at 1 tablet, up to 2 times a day, with a 3rd dose allowed if the symptoms come back, for ages 15 and over.

Updated October 3, 2026

68.1mgLoxoprofen Sodium Hydrate per dose

1 tabletAdult dose

Up to 2, a 3rd if neededDoses a day

第1類医薬品 · Class 1Pharmacist only

What is in Loxonin S

The package insert lists 1 active ingredient in 1 tablet. The middle column is how each one is written on the Japanese box.

Loxonin S: active ingredients in 1 tablet, from the Japanese package insert
Ingredient	Name on the box	Amount
Loxoprofen Sodium Hydrate(60 mg as anhydrate)	ロキソプロフェンナトリウム水和物	68.1 mg

Loxoprofen in Japan

Additives, as written on the package insert (Japanese)

ヒドロキシプロピルセルロース,ステアリン酸Mg,乳糖水和物,三二酸化鉄

The maker publishes an English package insert for LOXONIN S: Daiichi Sankyo Healthcare: LOXONIN S (English package insert). This page translates the current Japanese package insert on PMDA.

Source: PMDA (Pharmaceuticals and Medical Devices Agency) — ロキソニンS: package insert (添付文書) · Daiichi Sankyo Healthcare — LOXONIN S: English package insert

What the package insert lists it for

The approved wording of the Japanese package insert, translated. It is what the product is sold for, not advice on what to take.

Relief of headache, menstrual pain (period pain), toothache, pain after tooth extraction, throat pain, lower back pain, joint pain, neuralgia, muscle pain, pain from stiff shoulders, earache, pain from bruises, pain from fractures, pain from sprains and pain from injuries
Reducing fever when you have chills/fever

The dose, as written on the package insert

Translated line by line from the directions and dosage (用法・用量) section.

Loxoprofen Sodium Hydrate per dose: 68.1 mg
Adult dose: 1 tablet
Doses a day: Up to 2, a 3rd if needed
Age: 15 and over

Take the following amount with water or warm water.

Dose by age, as written on the package insert
Age	Single dose	Doses a day
Adults (15 and over)	1 tablet	Up to 2 times

Take it when symptoms appear, avoiding an empty stomach as far as possible.
However, if symptoms appear again, you may take a 3rd dose.
Take doses at least 4 hours apart.
Under 15: Do not take.

Notes on the directions

(1) Follow the directions and dosage exactly.
(2) How to take out the tablets: Press the raised part of the PTP sheet containing the tablet firmly with your fingertip to break the aluminium foil on the back, then remove the tablet and take it. (Accidentally swallowing it as it is can lead to unexpected accidents, such as it piercing the mucous membrane of the oesophagus)

Do not

The package insert opens with what you must not do.

(If you do not follow these, your current symptoms may get worse, and side effects become more likely)

1. Do not take it if you are one of the following people.

(1) People who have had allergic symptoms caused by this medicine or its ingredients
(2) People who have developed asthma after taking this medicine, or other pain and fever medicines or cold medicines
(3) Children under 15
(4) People who are receiving treatment for the following at a medical institution
Gastric/duodenal ulcer, liver disease, kidney disease, heart disease
(5) People who have been told by a doctor that they have a blood abnormality (blood disease), such as a low red blood cell count (anaemia), a low platelet count (bleeding that is hard to stop, bleeding easily) or a low white blood cell count
(6) Women within 12 weeks of their expected date of delivery

2. Do not take any of the following medicines while taking this medicine.

Other pain and fever medicines, cold medicines, sedatives

3. Do not drink alcohol before or after taking it.

4. Do not take it continuously for a long time.

(If symptoms such as pain keep coming back even after taking it for 3 to 5 days, stop taking it and see a doctor)

Ask a doctor, pharmacist or registered salesperson

The package insert says to ask for advice in these cases.

1. If you are one of the following people, ask a doctor, dentist or pharmacist for advice before taking it.

(1) People who are receiving treatment from a doctor or dentist
(2) Women who are pregnant or think they may be pregnant
(3) Women who are breastfeeding
(4) Older people
(5) People who have had allergic symptoms caused by medicines etc.
(6) People who have been diagnosed with the following
Bronchial asthma, ulcerative colitis, Crohn's disease, systemic lupus erythematosus, mixed connective tissue disease
(7) People who have had the following diseases
Gastric/duodenal ulcer, liver disease, kidney disease, blood disease

2. If the following symptoms appear after taking it, they may be side effects, so stop taking it immediately and ask a doctor, dentist or pharmacist for advice, taking this leaflet with you.

(1) If symptoms such as an excessive drop in body temperature, prostration (lack of strength) or coldness of the limbs (cold hands and feet) appear after taking a pain and fever medicine like this medicine
(2) If a peptic ulcer or oedema appears after taking it
Also, in rare cases the serious symptoms of gastrointestinal bleeding (vomiting blood, nausea/vomiting, abdominal pain, black tarry stools, bloody stools, etc. appear), gastrointestinal perforation (a hole forming in the digestive tract. Nausea/vomiting, severe abdominal pain, etc. appear) or narrowing/obstruction of the small/large intestine (nausea/vomiting, abdominal pain, abdominal distension, etc. appear) may occur. If they do, see a doctor immediately.
(3) If the following symptoms appear after taking it

Possible side effects, by part of the body

Skin: rash/redness, itching
Digestive system: abdominal pain, stomach discomfort, loss of appetite, nausea/vomiting, abdominal distension, heartburn, mouth ulcers, indigestion
Circulatory system: increased blood pressure, palpitations
Nervous system: drowsiness, numbness, dizziness, headache
Other: chest pain, lethargy, facial flushing, fever, anaemia, blood in the urine

In rare cases the following serious symptoms may occur. If they do, see a doctor immediately.

Rare but serious symptoms: name and signs

Shock (anaphylaxis): right after taking it, itchy skin, hives, hoarseness, sneezing, itchy throat, difficulty breathing, palpitations, clouding of consciousness, etc. appear.
Blood disorder: sore throat, fever, tiredness all over the body, the face and the inside of the eyelids looking whitish, bleeding easily (bleeding gums, nosebleeds, etc.), bruising (the colour does not fade when pressed), etc. appear.
Oculomucocutaneous syndrome (Stevens-Johnson syndrome): high fever, bloodshot eyes, eye discharge, sores on the lips, sore throat, widespread rash/redness on the skin, blisters appearing on red areas of the skin, small bumps (small pustules) appearing on reddened skin, the whole body feeling tired, having no appetite, etc. continue or rapidly get worse.
Toxic epidermal necrolysis: high fever, bloodshot eyes, eye discharge, sores on the lips, sore throat, widespread rash/redness on the skin, blisters appearing on red areas of the skin, small bumps (small pustules) appearing on reddened skin, the whole body feeling tired, having no appetite, etc. continue or rapidly get worse.
Erythema multiforme: high fever, bloodshot eyes, eye discharge, sores on the lips, sore throat, widespread rash/redness on the skin, blisters appearing on red areas of the skin, small bumps (small pustules) appearing on reddened skin, the whole body feeling tired, having no appetite, etc. continue or rapidly get worse.
Acute generalised exanthematous pustulosis: high fever, bloodshot eyes, eye discharge, sores on the lips, sore throat, widespread rash/redness on the skin, blisters appearing on red areas of the skin, small bumps (small pustules) appearing on reddened skin, the whole body feeling tired, having no appetite, etc. continue or rapidly get worse.
Kidney disorder: fever, rash, decreased amount of urine, oedema all over the body, tiredness all over the body, joint pain (aching joints), diarrhoea, etc. appear.
Congestive heart failure: tiredness all over the body, palpitations, shortness of breath, discomfort in the chest, chest pain, dizziness, fainting, etc. appear.
Myocardial infarction: chest pain that feels like being squeezed, difficulty breathing, breaking out in a cold sweat.
Cerebrovascular disorder: reduced/lost consciousness, difficulty moving the arm and leg on one side, headache, vomiting, dizziness, difficulty speaking, difficulty getting words out, etc. appear suddenly.
Interstitial pneumonia: shortness of breath/difficulty breathing when climbing stairs or exerting yourself a little, dry cough, fever, etc. are seen, and these appear suddenly or continue.
Liver dysfunction: fever, itching, rash, jaundice (the skin and the whites of the eyes turn yellow), brown urine, tiredness all over the body, loss of appetite, etc. appear.
Rhabdomyolysis: pain in the muscles of the arms and legs, shoulders, lower back, etc., numbness in the arms and legs, loss of strength, stiffness, the whole body feeling tired, reddish-brown urine, etc. appear.
Aseptic meningitis: severe headache accompanied by a stiff neck, fever, nausea/vomiting, etc. appear. (Such symptoms have been reported especially often in people who are receiving treatment for systemic lupus erythematosus or mixed connective tissue disease)
Asthma: wheezing or whistling sounds when breathing, difficulty breathing, etc. appear.

3. The following symptoms may appear after taking it, so if these symptoms continue or get worse, stop taking it and ask a doctor or pharmacist for advice, taking this leaflet with you.

Dry mouth, constipation, diarrhoea

4. If your symptoms do not improve after taking it 1 to 2 times (another illness may also be a possibility), stop taking it and ask a doctor, dentist or pharmacist for advice, taking this leaflet with you.

Other precautions

[Precautions related to the ingredients and amounts]
Depending on the tablet, red spots caused by an additive may be seen.

Who can sell it in Japan

The Loxonin S box carries the class 第1類医薬品, which decides who may sell it.

On the box: 第1類医薬品 (Class 1). The box reads 第1類医薬品.
Who can sell it: Only a pharmacist may sell it.
Information when you buy: The pharmacist must give the information in writing (on paper or on a screen). This can be skipped if you say you do not need it and the pharmacist judges you will use it properly.

The five classes on Japanese medicine boxes, side by side

Source: e-Gov law search (Digital Agency, Japan) — Pharmaceutical and Medical Device Act (医薬品医療機器等法), current text · e-Gov law search (Digital Agency, Japan) — Enforcement Regulations of the Pharmaceutical and Medical Device Act (施行規則), current text

Taking it home

Taking Japanese medicine home: the limits in South Korea, Taiwan, mainland China and Hong Kong

Frequently asked questions

How much Loxoprofen Sodium Hydrate is in Loxonin S?

68.1 mg in a dose of 1 tablet (60 mg as anhydrate), according to the Japanese package insert.

How much Loxonin S can an adult take in a day?

The package insert sets the adult dose at 1 tablet, up to 2 times a day, with a 3rd dose allowed if the symptoms come back. Doses are at least 4 hours apart.

Can children take Loxonin S?

No. The package insert says it is not to be taken under 15.

Do I need a pharmacist to buy Loxonin S?

Loxonin S is a class 1 medicine (第1類医薬品). Only a pharmacist may sell it.

What is Loxonin S called in Japanese?

ロキソニンS. The Loxonin S box also carries the class 第1類医薬品.