Erythema ab igne, aka fire stains, toasted skin syndrome, or hot water bottle rash, is a rash that occurs after exposure to heat. A reddish, purplish, or brownish discoloration appears in a lacy pattern. The rash is caused by repeated exposure to a heat source.
Some examples of these heat sources include:
– laptops – The rash occurs on the thighs where people rest their laptops.
– space heaters, infrared heaters – These direct heat to a confined area.
– hot water soaks – For example, frequent soaking of the feet in hot water.
– heating pads
– hot compresses
– hot water bottles
– chair heaters, car seat heaters
– hot stove
In most cases, the pigmentation from erythema ab igne eventually goes away. However, in some longstanding cases, the pigmentation does not resolve. In these longstanding cases, the skin may have a different texture as well. If you are diagnosed with erythema ab igne, your doctor will likely advise you to avoid continued use of the focal heat source that you are being exposed to.