Are there any long-term effects from nightly use of a heating pad for chronic back pain? The patient is concerned about skin and other cancers due to excessive exposure to the warmth.
—Gita Dalal, MD, Edison, N.J.

The most common complication reported from heating pad use is skin burns. Thermal injuries typically occur in patients who have sensory deficits, are taking sedating medications, or have recently ingested alcohol. The association with malignancy is a weak one, based largely on case reports, and often seen in patients who suffer from associated erythema ab igne (EAI). EAI is a rare dermatosis characterized by reticulated erythema, sometimes with associated hyperpigmentation. This disorder, thought to be caused by chronic repeated exposure to heat and infrared radiation from an external source, has been described with repeated use of heating pads, hot water bottles, and indoor fire as a heat source. The pathophysiology of the disorder is unclear. However, histopathologic changes resemble those seen in solar-damaged skin, and it is thought that the lesions may be precancerous. Indeed, there are several case reports of associated Merkel cell and squamous cell skin cancer development in areas of EAI (Br J Dermatol. 1993;28:591-592 and J Am Acad Dermatol. 1998;39:882-887). Mild EAI may resolve within several months if the heat application is stopped.
—Daniel G. Tobin, MD (99-14)