Non-selective NSAID Pregnancy: Contraindicated during pregnancy (SPC §4.3/§4.6). From the 20th week of pregnancy onward use may cause oligohydramnios from foetal renal dysfunction, and ductus arteriosus constriction has been reported in the second trimester. During the first and second trimester naproxen should not be given unless clearly necessary, at the lowest dose and shortest duration. Avoid in breast-feeding — naproxen has been found in the milk of lactating women. May impair fertility; not recommended in women attempting to conceive, and withdrawal should be considered in women undergoing investigation of infertility.

Naproxen

Brand names: Naprosyn, Napratec, Naproxen EC

Naproxen is a non-selective non-steroidal anti-inflammatory drug widely used in rheumatology for the symptomatic relief of pain and inflammation in conditions such as rheumatoid arthritis, osteoarthritis, gout and ankylosing spondylitis.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: 500 mg to 1 g daily

Route: Oral

Frequency: Taken in 2 doses at 12-hour intervals, or alternatively as a single administration

Max: Not stated for this indication in the SPC section retrieved (a maximum daily dose of 1250 mg after the first day is stated for acute musculoskeletal disorders and dysmenorrhoea)

Rheumatology variant. SPC §4.2 gives this regimen for rheumatoid arthritis, osteoarthritis and ankylosing spondylitis. A loading dose of 750 mg or 1 g per day for the acute phase is recommended in: (a) patients reporting severe night-time pain and/or morning stiffness; (b) patients being switched to naproxen from a high dose of another anti-rheumatic compound; (c) osteoarthrosis where pain is the predominant symptom. Undesirable effects may be minimised by using the lowest effective dose for the shortest duration necessary to control symptoms. Patients treated with NSAIDs long-term should undergo regular medical supervision to monitor for adverse events; prolonged use in older people and/or debilitated patients is not recommended. Treatment should be reviewed at regular intervals and discontinued if no benefit is seen or intolerance occurs. To be taken preferably with or after food. For juvenile rheumatoid arthritis in children over 5 years see paedDose.

Paediatric dose

Dose: 10 mg/kg

Route: Oral

Frequency: 10 mg/kg/day taken in 2 doses at 12-hour intervals

Max: Not stated in the SPC section retrieved

SPC states this for juvenile rheumatoid arthritis in the paediatric population over 5 years only. Naproxen is not recommended for use in any other indication in children under 16 years of age. Paediatric dosing must be verified against a children's formulary before use.

Dose adjustments

Renal

A lower dose should be considered in patients with renal or hepatic impairment. Contraindicated in patients with baseline creatinine clearance less than 30 ml/minute, because accumulation of naproxen metabolites has been seen in patients with severe renal failure or those on dialysis.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Paediatric weight-based calculator

Patient weight (kg)

Verify in a children's formulary

Contraindications

Active or history of peptic ulceration or active gastrointestinal bleeding (two or more distinct episodes of proven ulceration or bleeding)
History of gastrointestinal bleeding or perforation related to previous NSAID therapy
Hypersensitivity to naproxen or any of the excipients
Patients in whom aspirin or other NSAIDs induce asthma, rhinitis, nasal polyps or urticaria (potential for cross-sensitivity; reactions may be fatal)
Severe renal, hepatic or heart failure
Baseline creatinine clearance less than 30 ml/minute
Last trimester of pregnancy

Side effects

Gastrointestinal (most commonly observed): heartburn, nausea, vomiting, constipation, diarrhoea, flatulence, dyspepsia, abdominal discomfort and epigastric distress; more seriously GI bleeding (sometimes fatal, particularly in older people), ulceration, perforation and obstruction
Hypersensitivity reactions, including anaphylaxis, bronchospasm/aggravated asthma, and skin disorders (rashes, pruritus, urticaria, purpura, angio-oedema; rarely exfoliative and bullous dermatoses)
Nervous system: dizziness, headache, lightheadedness, drowsiness, paraesthesia, convulsions, aseptic meningitis (especially in patients with existing auto-immune disorders such as systemic lupus erythematosus or mixed connective tissue disease)
Cardiac/vascular: oedema, palpitations, cardiac failure, hypertension; small increased risk of arterial thrombotic events (e.g. myocardial infarction or stroke), particularly at high doses and in long-term treatment
Blood and lymphatic: neutropenia, thrombocytopenia, agranulocytosis, eosinophilia, leucopenia, aplastic anaemia, haemolytic anaemia
Hepatobiliary: jaundice, fatal hepatitis, abnormal liver function tests

Interactions

Oral corticosteroids — increased risk of gastrointestinal ulceration or bleeding (SPC §4.4)
Anticoagulants such as warfarin — increased risk of gastrointestinal ulceration or bleeding (SPC §4.4)
Selective serotonin-reuptake inhibitors — increased risk of gastrointestinal ulceration or bleeding (SPC §4.4)
Anti-platelet agents such as aspirin — increased risk of gastrointestinal ulceration or bleeding; combination therapy with protective agents (e.g. misoprostol or proton pump inhibitors) should be considered (SPC §4.4)

Clinical monograph

How it works

It non-selectively inhibits cyclo-oxygenase enzymes COX-1 and COX-2, reducing prostaglandin synthesis to produce anti-inflammatory, analgesic and antipyretic effects.

Prescribing in practice

Use the lowest effective dose for the shortest duration because of dose-related risks of serious gastrointestinal bleeding and ulceration, particularly in older patients and those on anticoagulants, with gastroprotection considered where appropriate.
It can cause fluid retention, raised blood pressure and renal impairment, so use caution in heart failure, hypertension and chronic kidney disease.
Avoid in active peptic ulceration and severe heart failure, and use cautiously with other nephrotoxic or anticoagulant drugs.

Monitoring

Monitor blood pressure, renal function and for gastrointestinal symptoms during longer-term use, especially in those with comorbidity.

Counselling the patient

Take with or after food and report black stools, vomiting blood or severe indigestion.
Avoid combining with other anti-inflammatory painkillers including over-the-counter ones.
Stay hydrated and report swelling or reduced urine output.

Evidence & guidelines

Naproxen is a first-line NSAID in UK rheumatology practice and is noted to carry a relatively favourable cardiovascular risk profile among NSAIDs in NICE guidance.

Reference: NICE NG100 RA; NICE NG219 Gout; MHRA NSAIDs prescribing guidance; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

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