Diclofenac is an anti-inflammatory painkiller — an NSAID. It is used for pain with an inflammatory component: arthritis, back and muscular pain, sprains and strains, period pain, gout and toothache. It comes as tablets, gel, suppositories and injection. It carries stomach, kidney and heart cautions that paracetamol does not.

What is Diclofenac?

Diclofenac is a non-steroidal anti-inflammatory drug, usually shortened to NSAID. It reduces pain, brings down fever and — the part that distinguishes it from a simple painkiller — reduces inflammation.

It works by blocking enzymes called cyclo-oxygenase, which the body uses to make prostaglandins. Prostaglandins drive inflammation, swelling and pain. They also protect the stomach lining and help regulate blood flow through the kidneys, which is exactly why the medicine’s benefits and its risks come from the same mechanism.

In South Africa it is dispensed under many names — Voltaren, Cataflam, K-Fenak, Diclo-Flam, Mylan Diclofenac and plain diclofenac from various manufacturers. You may see diclofenac sodium or diclofenac potassium; both are diclofenac, with the potassium salt absorbed somewhat faster.

It comes in several forms: tablets, topical gel, suppositories, eye drops and injection. These are not equivalent, and that matters more than people expect.

What is Diclofenac commonly used for?

Diclofenac is prescribed for pain where inflammation is part of the picture:

Arthritis — osteoarthritis, rheumatoid arthritis and other inflammatory joint conditions.
Back pain and muscular pain, particularly with associated inflammation.
Sprains, strains and sports injuries.
Period pain, where it is often more effective than paracetamol because the pain is prostaglandin-driven.
Gout flares.
Dental pain, including after extraction.
Post-operative pain, often by injection or suppository initially.
Eye inflammation, as drops, after surgery.

The gel deserves separate mention. Applied to a joint or muscle near the surface — a knee, an ankle, a hand — it delivers the medicine locally with far less reaching the rest of the body. For localised pain in someone who should be careful with oral NSAIDs, that is a genuinely useful option, and it is worth asking a pharmacist about.

How Diclofenac fits into this medicine category

Diclofenac sits in the NSAID group, and the distinction from its neighbours is practical rather than academic.

Simple analgesics such as paracetamol relieve pain without much anti-inflammatory effect. They are gentler on the stomach and suit people who cannot take NSAIDs.

Other NSAIDs — ibuprofen, meloxicam, naproxen, etoricoxib — do the same job with somewhat different profiles. Prescribers switch between them for tolerance and risk reasons.

Corticosteroids such as prednisone suppress inflammation far more powerfully, and are prescribed as courses for specific conditions rather than as everyday painkillers.

Compound painkillers add codeine for pain not controlled by simpler options.

The whole group is on the pain, inflammation and musculoskeletal medicines hub.

What to check before using Diclofenac

Take it with food, and use the lowest amount for the shortest time that works. Both reduce the risks below.

Speak to a doctor or pharmacist before taking oral diclofenac if:

You have a history of stomach ulcers, bleeding or reflux. NSAIDs are the leading medicine-related cause of stomach bleeding.
You have kidney disease, or are dehydrated. NSAIDs reduce blood flow to the kidneys.
You have heart disease, heart failure, high blood pressure, or have had a stroke. Diclofenac in particular carries a recognised cardiovascular risk, and in some countries its availability has been restricted for this reason.
You have asthma. A minority of people with asthma react badly to NSAIDs.
You take blood thinners, a corticosteroid, an SSRI antidepressant, a diuretic or an ACE inhibitor. Each combination raises a specific risk.
You are pregnant. NSAIDs are generally avoided, and specifically avoided in the third trimester.
You are over 65, where stomach and kidney risks are higher.

If you are already taking any other anti-inflammatory, do not add diclofenac. Two NSAIDs together multiply the risks without improving the relief.

Possible cautions and when to ask a pharmacist or doctor

The stomach is the main concern. NSAIDs can cause ulcers and bleeding, sometimes without warning pain beforehand. Risk rises with duration, age, alcohol, and combination with steroids or blood thinners. Where longer treatment is needed, a doctor may add a stomach-protecting medicine — which is the reasoning behind combination products that pair an NSAID with a proton pump inhibitor.

The kidneys are the second. Diclofenac can reduce kidney function, particularly if you are dehydrated, older, or taking blood-pressure medicines. During a vomiting or diarrhoeal illness, ask whether to pause it.

The heart is the third. Regular use at higher amounts is associated with increased cardiovascular risk. This is why the guidance is consistently the lowest effective amount for the shortest period.

Consider the gel where the pain is localised and near the surface. Far less reaches the rest of the body.

Stop and seek medical attention for stomach pain, vomiting blood or material like coffee grounds, black tarry stools, breathlessness, chest pain, one-sided weakness or slurred speech, marked swelling of the legs, a significant reduction in urine, or a rash with blistering. Persistent pain needs a diagnosis rather than continued anti-inflammatory use.

Related medicine guides

Frequently asked questions

What is diclofenac 50 mg used for? Pain with an inflammatory component — arthritis, back and muscular pain, sprains, period pain, gout and dental pain.

Is diclofenac stronger than ibuprofen? They are both NSAIDs and broadly comparable. People respond differently, and prescribers switch between them for tolerance rather than because one is universally stronger.

Can I take diclofenac with paracetamol? They are different medicines and are sometimes used together on advice. Do not combine diclofenac with another anti-inflammatory. Check for hidden paracetamol in combination products.

Is the gel safer than the tablets? For localised pain near the surface it delivers less medicine to the rest of the body, so systemic risks are lower. It is not risk-free, and the usual cautions still deserve a pharmacist’s input.

Can I take it for period pain? It is often effective, because that pain is prostaglandin-driven. The usual cautions about stomach, kidneys and other conditions still apply.

Why does it have to be taken with food? To reduce irritation of the stomach lining. It lowers the chance of discomfort, though it does not remove the risk of ulceration with longer use.

What Is Diclofenac Used For?