Local necrosis and interstitial nephritis due to topical methyl salicylate and menthol.

Excessive percutaneous absorption of potentially toxic substances such as menthol and methyl salicylate may occur through local application of heat, such as the use of a heating pad. Menthol and methyl salicylate are found in nonprescription items and used for muscular and arthritic pains. This patient experienced full-thickness skin and muscle necrosis as well as persistent interstitial nephritis as a result of topical application of methyl salicylate and menthol followed by use of a heating pad, despite the manufacturer's warning against the use of heating pads.