Diclofenac: uses, actions, formulations and safety

How it works

Diclofenac inhibits cyclooxygenase (COX) enzymes involved in prostaglandin synthesis. Although not classified as a highly selective COX-2 inhibitor, it shows some preferential activity that contributes to its anti-inflammatory effects. By lowering prostaglandin levels, diclofenac decreases pain signaling, local vascular dilation and inflammatory cell activity.

Formulations and administration

Diclofenac is produced in multiple forms: oral tablets and capsules, topical gels and creams, transdermal patches, injectable solutions and rectal suppositories. Topical preparations are applied directly to the affected area and can provide localized relief with lower systemic exposure, while oral or injectable forms are used for widespread or severe symptoms. Choice of formulation depends on the condition, patient preference and risk profile.

Clinical uses

Common indications include osteoarthritis, rheumatoid arthritis, ankylosing spondylitis, acute soft-tissue injuries such as bruises and strains, dysmenorrhea and short-term management of postoperative pain. It is used as an analgesic and antipyretic in many settings. Treatment is typically guided by the lowest effective dose for the shortest practical duration to limit adverse effects.

Safety, side effects and precautions

Like other NSAIDs, diclofenac can cause gastrointestinal irritation, ulceration and bleeding; risk increases with higher doses and prolonged use. Renal function can be affected, especially in volume-depleted patients or those with preexisting kidney disease. Some studies have associated diclofenac with an elevated risk of cardiovascular events such as heart attack and stroke, prompting caution in people with cardiovascular disease or risk factors. Hypersensitivity reactions and asthma exacerbation may occur in susceptible individuals. It is generally avoided in late pregnancy because NSAIDs can affect fetal circulation.

History and notable facts

Diclofenac has been available for several decades and became a commonly used NSAID due to its potency and multiple routes of administration. Research and post-marketing surveillance over the years have led to updated labeling and guidance about cardiovascular and gastrointestinal risks; clinicians balance benefits and harms when choosing diclofenac versus alternative analgesics or anti-inflammatory agents. Patients should discuss medical history, current medications and monitoring needs with their prescriber before starting diclofenac.