Anyone who’s ever had an owie after cleaning out the garage or trying to match Paul Ryan’s P90X regimen is probably familiar with names like Bengay, Flexall and Icy Hot. They are topical analgesics you apply to sore, complaining muscles and joints.

As of last month, the FDA has issued a warning about such creams, gels or skin patches because some people have reported burning pain and blistering ranging from mild to severe. Some injuries have required medical attention.

In some cases, the FDA reports, these over-the-counter (OTC) treatments caused first- to third-degree chemical burns after only one application. Symptoms appeared within 24 hours, and some people had complications serious enough to be hospitalized.

There have been 43 reported cases of burns associated with the use of OTC topical muscle and joint pain relievers containing the active ingredients menthol, methyl salicylate and capsaicin. They came to light through the FDA's adverse event reporting database and the medical literature.

Millions of people use these products, so the number of reported adverse events represents a tiny fraction of consumers. But, "There's no way to predict who will have this kind of reaction to a topical pain reliever for muscles and joints," said Dr. Jane Filie of the FDA's Division of Nonprescription Regulation Development.

Menthol, methyl salicylate and capsaicin create sensations of local warmth or coolness when applied directly to the skin, but they should not burn. Most of the severe cases occurred with products containing menthol or a menthol/methyl salicylate combination. Most involved concentrations of menthol and methyl salicylate greater than 3 percent and 10 percent, respectively. Few burn cases involved capsaicin.

If you are using an OTC topical analgesic for the first time, choose one that isn’t a combination product and one with lower concentrations of active ingredients. If your pain persists, and you have tolerated those compounds, graduate to a more powerful treatment.

Otherwise, the FDA advises:

• Don't apply these products onto damaged or irritated skin.
• Don't apply bandages to the area where you've applied a topical muscle and joint pain reliever.
• Don't apply heat to the area (heating pads, hot water bottles, lamps). Doing so increases the risk of serious burns.
• Keep these products away from eyes and mucous membranes (such as the skin inside your nose, mouth or genitals).
• If, instead of a warming or cooling sensation, you feel pain where you’ve applied the product, if it looks blistered or burned, stop using the product and seek medical attention. 

Report any unexpected side effects from the use of an OTC topical pain reliever to the FDA’s MedWatch program. [www.fda.gov/Safety/MedWatch/default.htm] And to learn more, link to the FDA’s backgrounder, “Topical Pain Relievers May Cause Burns.”