NSAID (Non-Steroidal Anti-Inflammatory Drug) Pregnancy: Contraindicated during pregnancy. Inhibition of prostaglandin synthesis may adversely affect the pregnancy and/or embryo/foetal development; epidemiological data suggest an increased risk of miscarriage, cardiac malformation and gastroschisis after use in early pregnancy. From the 20th week of pregnancy onward, use may cause oligohydramnios resulting from foetal renal dysfunction, and ductus arteriosus constriction has been reported following second-trimester treatment. During the third trimester all prostaglandin synthesis inhibitors may expose the foetus to cardiopulmonary toxicity and renal dysfunction, and the mother and neonate to possible prolongation of bleeding time and inhibition of uterine contractions. Naproxen has been found in the milk of lactating women and use should be avoided in patients who are breast-feeding.

Naproxen

Brand names: Naprosyn, Feminax Ultra

Naproxen is a non-steroidal anti-inflammatory drug (NSAID) used for pain, inflammation and gout; in older people it carries heightened gastrointestinal, renal and cardiovascular risks.

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 (rheumatoid arthritis, osteoarthritis and ankylosing spondylitis) — in older people use the lowest effective dose for the shortest duration possible

Route: Oral (to be taken preferably with or after food)

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

Max: For acute musculoskeletal disorders and dysmenorrhoea, a maximum daily dose after the first day of 1250 mg

Older people context. Source: Naproxen 250 mg Tablets (UK SPC). OLDER PEOPLE: studies indicate that although total plasma concentration of naproxen is unchanged, the unbound plasma fraction of naproxen is increased in older people; the implication of this finding for naproxen dosing is unknown. As with other drugs used in older people it is prudent to use the lowest effective dose and for the shortest duration possible, as older people are more prone to adverse events. The patient should be monitored regularly for GI bleeding during NSAID therapy — GI bleeding is sometimes fatal, particularly in older people. The SPC gives no separate numeric geriatric dose; the adult regimens below apply. Rheumatoid arthritis, osteoarthritis and ankylosing spondylitis: 500 mg to 1 g taken in 2 doses at 12-hour intervals or alternatively as a single administration; 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 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 6-8 hour intervals as needed, maximum daily dose after the first day 1250 mg. Renal/hepatic impairment: a lower dose should be considered. Treatment should be reviewed at regular intervals and discontinued if no benefit is seen or intolerance occurs. US labelling (cross-check) adds that elderly patients, compared with younger patients, are at greater risk for NSAID-associated serious cardiovascular, gastrointestinal and/or renal adverse reactions; if the anticipated benefit outweighs these potential risks, start dosing at the low end of the dosing range and monitor for adverse effects.

Paediatric dose

Dose: 10 mg/kg

Route: Oral

Frequency: Per day, taken in 2 doses at 12-hour intervals

Paediatric population (over 5 years), for juvenile rheumatoid arthritis: 10 mg/kg/day taken in 2 doses at 12-hour intervals. Naproxen is not recommended for use in any other indication in children under 16 years of age. Included for completeness only — this entry is the older-people context. Verify against a children's formulary.

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. Also contraindicated in severe renal failure. Particularly relevant in older people, who are at greater risk of NSAID-associated renal adverse reactions.

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 the syndrome of asthma, rhinitis, nasal polyps or urticaria (potential for cross-sensitivity reactions, which have the potential of being fatal)
Severe renal, hepatic or heart failure
During pregnancy (contraindicated during the last trimester; see section 4.6)

Side effects

Gastrointestinal (most commonly observed): heartburn, nausea, vomiting, constipation, diarrhoea, flatulence, dyspepsia, abdominal discomfort and epigastric distress; more serious reactions include GI bleeding (sometimes fatal, particularly in older people), ulceration, perforation and obstruction, melaena, haematemesis, exacerbation of ulcerative colitis and Crohn's disease, oesophagitis, gastritis and pancreatitis
Hypersensitivity reactions: nonspecific allergic reactions and anaphylaxis; respiratory tract reactivity including 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: convulsions, dizziness, headache, lightheadedness, drowsiness, paraesthesia, retrobulbar optic neuritis, inability to concentrate and cognitive dysfunction; aseptic meningitis (especially in patients with existing auto-immune disorders)
Cardiac/vascular: oedema, palpitations, cardiac failure and congestive heart failure; hypertension, vasculitis. Clinical trial and epidemiological data suggest that use of 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 (e.g. myocardial infarction or stroke)
Blood and lymphatic system: neutropenia, thrombocytopenia, granulocytopenia including agranulocytosis, eosinophilia, leucopenia, aplastic anaemia and haemolytic anaemia. Hepatobiliary: jaundice, fatal hepatitis and abnormal liver function tests

Interactions

Anticoagulants such as warfarin — synergistic effect on bleeding; increased risk of serious bleeding compared with either drug alone; monitor for signs of bleeding (US labelling)
Antiplatelet agents (e.g. aspirin), SSRIs and SNRIs — concomitant use may potentiate the risk of bleeding more than an NSAID alone; monitor for signs of bleeding (US labelling)
Aspirin — a pharmacodynamic study demonstrated that lower-dose naproxen (220 mg/day or 220 mg twice daily) interfered with the antiplatelet effect of low-dose immediate-release aspirin, the interaction being most marked during the naproxen washout period (US labelling)

Clinical monograph

How it works

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

Prescribing in practice

In older patients the gastrointestinal bleeding, renal and cardiovascular risks are increased, so use the lowest effective dose for the shortest time and consider gastroprotection, particularly with other risk factors.
Avoid or use caution with anticoagulants, antiplatelets, ACE inhibitors/ARBs and diuretics, and in heart failure, peptic ulcer disease or significant renal impairment.
Among non-selective NSAIDs naproxen carries comparatively lower cardiovascular thrombotic risk, which may favour it when an NSAID is needed in a patient with cardiovascular concerns.

Monitoring

Monitor renal function and blood pressure, and remain alert for gastrointestinal symptoms, especially in dehydrated or polypharmacy patients.

Counselling the patient

Take with or after food and report black stools, vomiting blood or persistent indigestion.
Avoid combining with other anti-inflammatory painkillers, including over-the-counter products.
Report ankle swelling, breathlessness or reduced urine output.

Evidence & guidelines

Cardiovascular safety meta-analyses indicate naproxen has a lower thrombotic risk than several other NSAIDs, while MHRA guidance reinforces gastrointestinal and renal caution in older adults.

Reference: NICE CG177 (Gout); NICE NG226 (Osteoarthritis); AGS Beers Criteria 2023; STOPP/START v3; 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.

Calculators

Drugs

Diclofenac · NSAID (Non-Steroidal Anti-Inflammatory Drug)

Pathways