Naproxen UK Guide: Dosage, Uses, Side Effects and Interactions

All indications, correct doses, timing, side effects, drug interactions, contraindications and how to get naproxen in the UK.

Part of the Access Doctor Pain guide. For naproxen specifically for period pain, see Naproxen for Period Pain.

What Is Naproxen?

Naproxen is a non-selective non-steroidal anti-inflammatory drug (NSAID) that inhibits both COX-1 and COX-2 cyclooxygenase enzymes. Blocking these enzymes reduces the synthesis of prostaglandins and thromboxanes — the inflammatory mediators responsible for pain, swelling, fever and, in the uterus, the cramps of dysmenorrhoea.

Naproxen has been in clinical use since the 1970s and has a long, well-documented safety record at recommended doses. In the UK it's available over the counter as naproxen sodium 250mg tablets (branded Feminax Ultra, licensed solely for period pain) and on prescription as naproxen 500mg tablets. Both share the same mechanism; the sodium salt in the OTC preparation is absorbed slightly faster.

What Is Naproxen Used For?

• Period pain (dysmenorrhoea) — NICE first-line; the 500mg twice-daily prescription dose is particularly effective; see Naproxen for Period Pain
• Musculoskeletal pain — back pain, sprains, strains, soft tissue injuries
• Osteoarthritis — for acute flares and ongoing joint pain
• Rheumatoid arthritis — anti-inflammatory management of joint inflammation
• Gout — effective for acute attacks (750mg initially, then 250mg every 8 hours)
• Ankylosing spondylitis
• Post-operative and procedural pain
• Dental pain

Dosage

How to Take Naproxen

• Always take with food or milk — this is the single most effective way to reduce GI side effects
• Swallow whole with a full glass of water
• For period pain: start at the first sign of bleeding or pain — don't wait for it to build
• Don't exceed the stated dose
• Don't combine with another NSAID (ibuprofen, aspirin at analgesic doses, diclofenac)
• Avoid alcohol — it increases the risk of stomach irritation and bleeding

Side Effects

Common (up to 1 in 10)

• Nausea, heartburn, indigestion, stomach discomfort
• Headache, dizziness
• Mild fluid retention (ankle swelling)

Less common but worth knowing

• Raised blood pressure — worth monitoring if you use naproxen regularly
• Impaired kidney function with prolonged use
• Skin reactions (rash)

Contraindications

• Active peptic ulcer disease or GI bleeding history — unless with gastroprotective PPI cover under prescriber guidance
• Significant renal impairment (eGFR <30) — NSAIDs reduce renal blood flow
• Aspirin-sensitive asthma / NSAID hypersensitivity
• Third trimester of pregnancy — risk of premature closure of the ductus arteriosus
• Severe heart failure
• Severe hepatic impairment

Use with caution, and only after prescriber assessment: age over 65; cardiovascular disease; anticoagulant use; concurrent corticosteroids or SSRIs; mild-to-moderate renal impairment; first and second trimester pregnancy.

Key Drug Interactions

Naproxen vs Ibuprofen: Key Differences

How to Get Naproxen in the UK

Naproxen 500mg is a prescription-only medicine in the UK. There are two legitimate ways to get it:

• NHS prescription via your GP — naproxen is a standard NHS treatment for joint pain, arthritis, gout and period pain. In England the NHS prescription charge is currently £9.90 per item (free in Scotland, Wales and Northern Ireland, and free in England if you qualify for an exemption).
• Private UK prescription online — if you'd rather not wait for a GP appointment, UK-registered online pharmacies such as Access Doctor can assess you and issue a private prescription following a short consultation with a GPhC-registered pharmacist independent prescriber.

The only naproxen you can buy over the counter in the UK is Feminax Ultra — a 250mg naproxen sodium product licensed specifically for period pain in women aged 15–50. It's stocked by Boots, Superdrug and most high-street pharmacies. For any other indication, and for the 500mg strength, you need a UK prescription.

All medicines dispensed by Access Doctor are MHRA-licensed UK products, and delivery is UK-only, usually next working day in discreet packaging.

Naproxen at treatment doses needs a UK prescription — but not a GP appointment. Access Doctor's GPhC-registered UK pharmacist independent prescribers review consultations the same day and dispatch approved orders for next-working-day UK delivery in discreet packaging.