Non-steroidal anti-inflammatory drugs (NSAIDs) are called topical when they come in a form that you can rub onto your skin, rather than swallow as a pill.
Topical NSAIDs can bring relief for mild to moderate osteoarthritis pain, especially in the hands or knees. Some studies show they relieve pain as well as their oral counterparts, and they may be less irritating on the stomach.
One such NSAID is called diclofenac. It comes in a gel form and is sold under brand names such as Voltaren©, Pennsaid© and Solaraze©.
When an NSAID is applied to the skin over the site of pain, the medicine is delivered more directly. While the drug does not enter the gastrointestinal tract, some of the drug does get absorbed into the blood stream, so topical NSAIDs are not completely free of potential side effects.
Topical NSAIDs are likely to be most effective for joints nearer the surface of the skin, where the medication can more easily penetrate the affected area. They may be less effective for joints deeper in the body, such as the spine.
— Orthopaedic surgeon Steven Maschke, MD