Topical nonsteroidal anti-inflammatory drugs (NSAIDS) are applied to the skin in the form of a gel, cream, or spray in the region where pain is experienced (a sprained ankle, for instance). They are typically used for strains or sprains, rather than headache or abdominal pain. The attraction of topical application of NSAIDS is that blood concentrations are typically less than 1/20th of those found with oral NSAIDs, minimising the risk of serious harm.
Topical NSAIDs have to penetrate the skin, enter tissues or joints, and be present in a high enough concentration to have an effect on the inflammatory processes causing pain. The evidence from a large number of studies is that topical NSAIDs work well, though evidence for good effect is available only for topical diclofenac, ibuprofen, ketoprofen, and piroxicam. About 6 or 7 out of 10 patients will have successful pain control over seven days with topical NSAID, compared with 4 out of 10 with placebo; the high response with placebo is because conditions like sprained ankles tend to get better on their own eventually. For every four or five participants treated with one of these topical NSAIDs, one would experience good pain relief (equivalent to at least 50% reduction) after about one week, who would not have done if treated with placebo.
Local adverse events at the site of application are no worse with topical NSAID than with topical placebo; they are mild and transient, and occur in about 6% of participants. Systemic adverse events (nausea, stomach upset, for example) and adverse event withdrawals were uncommon, occurring no more frequently with topical NSAID than topical placebo. No serious adverse events were reported in these studies.