Doctors across the globe are cautioning parents, students, and working adults about a rare but increasingly recognized skin condition linked to one of the most common daily habits: resting a running laptop directly on bare skin.
The warning follows a case report published in the British Medical Journal's Case Reports section, in which physicians described a child who developed a distinctive darkened rash on the thighs after prolonged, repeated use of a laptop placed on bare legs. The rash displayed the classic reticulated, fishnet-like pattern that dermatologists associate with erythema ab igne — a condition whose name literally translates to "redness from fire."
Erythema ab igne occurs when skin is exposed to chronic low-grade heat — typically in the range of 43 to 47 degrees Celsius — over weeks or months. The heat damages small blood vessels just beneath the skin's surface, causing dilation, inflammation, and eventual hyperpigmentation. Historically, the condition was most often seen in people who sat close to open fires, coal stoves, or heating lamps. But in recent years, case reports from the United States, Europe, Asia, and Australia have documented a sharp rise in laptop-related occurrences, particularly among young people who use computers for extended study sessions on their laps.
In the BMJ case, the child's presentation — a symmetrical, mottled network of brownish-red discoloration on both thighs — matched textbook diagnostic criteria. Doctors noted that early stages of the condition are often reversible if the heat source is removed, but prolonged exposure can lead to persistent or permanent pigmentary changes. In very rare, long-standing cases, erythema ab igne has been linked to malignant transformation, though such outcomes are uncommon and typically involve years of continuous heat exposure.
Dermatologists stress that laptop surfaces may not feel dangerously hot to the touch, even when temperatures are sufficient to cause cellular damage over time. The devices generate consistent infrfrared heat during normal operation, and users often do not perceive discomfort until visible skin changes have already appeared. Experts recommend using a desk or lap table whenever possible, avoiding prolonged direct contact, and taking regular breaks to allow the skin to cool. For those who already show early signs, stopping heat exposure usually results in gradual fading, though complete recovery may take several months.
