NSAID Pregnancy: Contraindicated during pregnancy (§4.6 concludes 'Consequently, Naproxen is contraindicated during pregnancy'; §4.3 states it is contraindicated during the last trimester). Data suggest an increased risk of miscarriage, cardiac malformation and gastroschisis after use of a prostaglandin synthesis inhibitor in early pregnancy. From the 20th week 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 trimesters naproxen should not be given unless clearly necessary, at the lowest dose and shortest duration, with antenatal monitoring for oligohydramnios and ductus arteriosus constriction considered after several days of exposure from gestational week 20. Breast-feeding: naproxen is found in breast milk and use should be avoided. Fertility: may impair fertility and is not recommended in women attempting to conceive.

Naproxen

Brand names: Naprosyn, Naprogesic

Naproxen is a non-selective non-steroidal anti-inflammatory drug (NSAID) widely used for musculoskeletal pain, inflammation and acute gout in orthopaedic and trauma settings.

Adult dose

Dose: Rheumatoid arthritis, osteoarthritis and ankylosing spondylitis: 500 mg to 1 g daily, taken in 2 doses at 12-hour intervals or alternatively as a single administration

Route: Oral - to be taken preferably with or after food

Frequency: In 2 doses at 12-hour intervals, or as a single daily administration

Max: Acute musculoskeletal disorders and dysmenorrhoea: maximum daily dose after the first day of 1250 mg. No separate overall maximum is stated in §4.2 for the rheumatic indications, where the stated range is 500 mg to 1 g daily.

Undesirable effects may be minimised by using the lowest effective dose for the shortest duration necessary to control symptoms. LOADING DOSE: in the rheumatic indications a loading dose of 750 mg or 1 g per day for the acute phase is recommended (a) in patients reporting severe night-time pain and/or morning stiffness, (b) in patients being switched to naproxen from a high dose of another anti-rheumatic compound, and (c) in osteoarthrosis where pain is the predominant symptom. ACUTE GOUT: 750 mg at once, then 250 mg every 8 hours until the attack has passed. ACUTE MUSCULOSKELETAL DISORDERS AND DYSMENORRHOEA: 500 mg initially followed by 250 mg at 6 to 8 hour intervals as needed, with a maximum daily dose after the first day of 1250 mg. OLDER PEOPLE: the unbound plasma fraction of naproxen is increased although total plasma concentration is unchanged; the implication for dosing is unknown, so it is prudent to use the lowest effective dose for the shortest duration possible as older people are more prone to adverse events, and the patient should be monitored regularly for GI bleeding during NSAID therapy. Treatment should be reviewed at regular intervals and discontinued if no benefit is seen or intolerance occurs. Naproxen is not recommended for use in any indication other than juvenile rheumatoid arthritis in children under 16 years of age.

Paediatric dose

Dose: 10 mg/kg

Route: Oral

Frequency: Total daily dose, taken in 2 doses at 12-hour intervals

Max: Not stated in source for the paediatric regimen

THIS IS 10 mg/kg PER DAY, NOT PER DOSE. Exact SPC wording (§4.2, Paediatric population, over 5 years): 'For juvenile rheumatoid arthritis: 10mg/kg/day taken in 2 doses at 12-hour intervals.' The regimen applies to children over 5 years with juvenile rheumatoid arthritis only; naproxen is not recommended for use in any other indication in children under 16 years of age. Verify all under-18 dosing against a children's formulary.

Dose adjustments

Renal

A lower dose should be considered in patients with renal or hepatic impairment. Naproxen is 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 independently re-sourced from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — clinician-reviewed. 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, naproxen sodium, or any of the excipients
Patients in whom aspirin or other NSAIDs induce the syndrome of asthma, rhinitis, nasal polyps or urticaria - cross-sensitivity reactions have the potential to be fatal and severe anaphylactic-like reactions have been reported
Severe renal, hepatic or heart failure
The last trimester of pregnancy

Side effects

Gastrointestinal - heartburn, nausea, vomiting, constipation, diarrhoea, flatulence, dyspepsia, abdominal discomfort and epigastric distress; more seriously gastrointestinal bleeding (sometimes fatal, particularly in older people), ulceration, perforation and obstruction, melaena, haematemesis, and exacerbation of ulcerative colitis and Crohn's disease
Hypersensitivity reactions - non-specific allergic reactions and anaphylaxis; respiratory tract reactivity comprising asthma, aggravated asthma, bronchospasm or dyspnoea; skin disorders including rashes, pruritus, urticaria, purpura, angio-oedema and more rarely exfoliative and bullous dermatoses (including epidermal necrolysis and erythema multiforme)
Nervous system - dizziness, headache, lightheadedness, drowsiness, paraesthesia, inability to concentrate, cognitive dysfunction, convulsions, and aseptic meningitis (especially in patients with existing autoimmune disorders)
Cardiovascular - oedema, palpitations, cardiac failure and congestive heart failure, hypertension, vasculitis; coxibs and some NSAIDs (particularly at high doses and in long-term treatment) may be associated with a small increased risk of arterial thrombotic events such as myocardial infarction or stroke
Blood and lymphatic system - neutropenia, thrombocytopenia, granulocytopenia including agranulocytosis, eosinophilia, leucopenia, aplastic anaemia and haemolytic anaemia
Renal and hepatobiliary - hyperkalaemia; jaundice, fatal hepatitis and abnormal liver function tests

Interactions

Anticoagulants such as warfarin - synergistic effect on bleeding; concomitant use carries an increased risk of serious bleeding compared with either drug alone; monitor for signs of bleeding (US label §7)
Antiplatelet agents, SSRIs and SNRIs - concomitant use may potentiate the risk of bleeding more than an NSAID alone; monitor for signs of bleeding (US label §7)
Aspirin - lower-dose naproxen (220 mg/day or 220 mg twice daily) interfered with the antiplatelet effect of low-dose immediate-release aspirin, most marked during the naproxen washout period (US label §7)
This interaction list may be incomplete — check the full SPC. Some of this information is from US labelling, which may differ from the UK SPC — check the full SPC.

Clinical monograph

How it works

It inhibits cyclo-oxygenase enzymes (COX-1 and COX-2), reducing prostaglandin synthesis and thereby decreasing inflammation, pain and fever.

Prescribing in practice

Carries gastrointestinal bleeding and ulceration risk, so use the lowest effective dose for the shortest time and consider gastroprotection in at-risk patients.
Avoid or use with caution in renal impairment, heart failure and uncontrolled hypertension, and in patients on anticoagulants or other NSAIDs.
Of the non-selective NSAIDs, naproxen carries a comparatively lower cardiovascular thrombotic risk, which can guide choice in cardiovascular disease.

Monitoring

Monitor blood pressure, renal function and for gastrointestinal symptoms during prolonged or higher-dose use.

Counselling the patient

Take with or after food to reduce stomach upset.
Report black stools, vomiting blood, or significant indigestion promptly.
Avoid taking other anti-inflammatory painkillers at the same time.

Evidence & guidelines

MHRA advice and NICE guidance support using the lowest effective NSAID dose for the shortest duration, noting naproxen's relatively favourable cardiovascular profile.

Reference: ACR Gout Guidelines 2020; BSR Gout Guidelines 2017; 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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