Naproxen vs diclofenac: two anti-inflammatory painkillers compared

Naproxen and diclofenac are both NSAIDs, a group that also includes ibuprofen and aspirin. They work by reducing inflammation and pain, and are used for conditions including arthritis, back pain, sprains, period pain and gout. Because they belong to the same class, they share the same major warnings, and they should not be taken together.

The NHS says naproxen can help with period pain, joint and muscle pain, gout, osteoarthritis and rheumatoid arthritis. For diclofenac it lists aches and pains and problems with joints, muscles and bones, including arthritis, sprains, back pain, migraines and after dental surgery.

The practical differences are mostly about form and use. Diclofenac has a wider range of formulations: prescription tablets and capsules (including slow-release), suppositories, gel, plasters and patches for joint pain that you can buy from pharmacies, and hospital injections or eyedrops. The NHS says gel and plasters can be used twice a day to target a particular area, and are less likely to cause side effects because less medicine gets into the body.

Naproxen comes as tablets, a liquid or effervescent tablets, usually taken up to 3 times a day, with some types available without prescription for short-term use only. The NHS says not to take naproxen for longer than 3 days if you bought it without a prescription, and to see a GP if symptoms get worse or do not improve.

The NHS lists stomach ulcers or bleeding inside the stomach, kidney problems, blood problems, heart failure and allergic reaction among serious side effects for naproxen, and says the risk is higher with a high dose or long-term use. For diclofenac it lists black poo, severe indigestion or stomach pain, liver problems, hives or swelling, signs of heart failure, and signs of heart attack or stroke as serious or emergency symptoms, and says taking diclofenac long term or in high doses can damage the stomach.

Both may not be suitable if you have had an allergic reaction to an NSAID, stomach ulcers or bleeding, a heart, liver or kidney condition, asthma, a blood clotting problem, or Crohn's disease or ulcerative colitis. Diclofenac also lists high blood pressure and lupus. Naproxen should be avoided in pregnancy unless advised, and is not usually used while breastfeeding, where ibuprofen is described as safer. For diclofenac, pregnancy and breastfeeding are listed among reasons to check with a doctor.

A doctor may add a stomach-protecting medicine such as omeprazole if you need either for a long time.

For naproxen, the NHS lists anticoagulants such as warfarin, steroid medicines, some antidepressants such as citalopram, diuretics, medicines for heart problems and high blood pressure, and methotrexate. Do not take naproxen at the same time as other NSAIDs such as ibuprofen or aspirin. The same principle applies to diclofenac: tell your doctor or pharmacist about all medicines and avoid doubling up on anti-inflammatory painkillers, including those bought over the counter.

There is no single better NSAID. The choice depends on what is being treated, where the pain is, how long treatment is needed, other health conditions and other medicines. For one painful joint, a topical diclofenac gel may be considered because less medicine gets into the body. For widespread inflammatory pain, a tablet may be needed, with stomach protection. A pharmacist or GP can advise which suits you. The existing comparison of ibuprofen and naproxen on this site covers a related question.