Space Heater Rash: What is Toasted Skin Syndrome? Posted on October 29, 2025 It’s heating season once again, and with it comes one of those irritating seasonal rashes: space heater rash. If you’ve ever sat too close to a space heater or a heating pad and noticed a lace-like red or brown patch of skin, you may have seen the early stages of toasted skin syndrome. This guide explains what space heater rash aka toasted skin syndrome is and what it looks like. We also discuss what causes it, how doctors treat it, and — most importantly — practical ways to keep you and your family safe this fall. Quick summary What it is: Space heater rash is a skin reaction from repeated exposure to low-level heat or infrared radiation that doesn’t burn, but damages skin over time. It often forms a net-like (reticulated) patch of redness that can darken to brown. Common culprits: Space heaters, heating pads, electric blankets, hot water bottles, car seats, laptops. Main treatment: Stop the heat exposure; early lesions can fade. Chronic cases may need dermatology treatments (topical retinoids, laser, or specialist procedures). Rarely, biopsy is needed because long-standing lesions can show pre-malignant changes. What is Space Heater Rash / Toasted Skin Syndrome? Clinically known as Erythema ab igne (Latin: “redness from fire”), space heater rash is a thermally induced skin condition caused by chronic, repeated exposure to moderate heat or infrared radiation. Unlike an acute thermal burn, the heat level is below the burn threshold but applied often enough (and close enough) that it causes vascular and pigment changes in the skin. This causes the skin to turn from pink/red reticulation to brown hyperpigmentation and sometimes thinning. Historically toasted skin syndrome was caused by open fires or old electric heaters. Today, it is also caused by laptops, heating pads, and space heaters. Space Heater Rash vs Heat Rash Space heater rash is different from “heat rash” (miliaria), which is caused by blocked sweat glands. The latter appears as small bumps or blisters and typically happens during hot, humid conditions when the skin’s sweat glands get blocked and are unable to release sweat. In contrast, Erythema ab igne results from repeated low-level heat exposure and usually happens during the cold season. Why Space Heaters Cause Toasted Skin Syndrome Space heaters emit radiant heat and infrared energy (see our past article for how they work). When a person’s skin is constantly within the heater’s direct zone (such as bare legs placed close to a portable heater for hours), the skin’s small blood vessels dilate repeatedly. This causes dermal structures to get slowly damaged. Over weeks to months this produces the characteristic net-like discoloration on the skin, which are actually the damaged blood vessels. Because space heaters are used for direct heating, they typically cause most of the rashes seen during the cold season. Here’s an example of a medical case where a space heater caused toasted skin syndrome. Apart from space heaters, other prolonged heat sources can have the same effect, including heating pads, heated car seats, and even laptops placed on one’s lap for long periods of time. People who use heat for chronic pain (such as frequent heating pad users) may also be at higher risk. Space Heater Rash: Signs & Symptoms Erythema ab igne doesn’t show up all of a sudden like acne. It is a typical progression that develops over time. Where it commonly occurs: Areas repeatedly exposed to heat Lower legs Anterior thighs Lower back Abdomen Lap (for laptop users) For space heater-caused rashes, they usually appear on the front of the legs. Early signs: Faint, patchy pink or red areas in a lace-like pattern Affected skin has a slightly itchy/burning feeling Established: Brownish hyperpigmentation with a reticulated pattern May show telangiectasias (small visible blood vessels) Mild scaling of the skin Chronic: Pigment changes may become long-lasting or permanent Long-standing skin lesions Diagnosis Diagnosis is generally clinical: the distinctive net-like discoloration plus a history of repeated heat exposure is usually enough to confirm the rash. When in doubt, doctors mayrequest for a biopsy to be taken to rule out other causes. This is important to distinguish the rash from other skin ailments that have similar symptoms such as vasculitis, cutaneous lupus, or even early skin cancer. Treatment Remove the heat source The single most important step. Based on the medical literature, early lesions will often improve or clear after eliminating the exposure, in this case, the space heater. Topical treatments Dermatologists can prescribe retinoids (such as tretinoin) or topical bleaching/depigmenting agents to improve or restore skin pigmentation In some cases, short courses of low-potency topical steroids can also soothe inflamed skin. Note that such topical treatments must be prescribed by a medical professional. Procedural treatments For persistent pigmentation or telangiectasias, the doctor or dermatologist can recommend laser resurfacing, chemical peels, or other dermatologic procedures. These are usually reserved for established or chronic cases, where topical treatments may not be enough or no longer effective. Biopsy and further workup If the lesion/s are persistent, ulcerated, or show suspicious changes, a biopsy may be needed to exclude rare malignant transformations. Some case reports have shown squamous cell carcinoma, a type of skin cancer, arising from longstanding EAI lesions. How long does it take to go away? Recovery depends on how long the toasted skin syndrome has been occurring. For early rashes: weeks to months after removing the heat exposure. For Longstanding hyperpigmentation: these can persist for months, years, or sometimes be permanent despite treatment. Prevention: How to Reduce Risk Space heater rash is truly one of those ailments where prevention is better than cure, as it risks becoming permanent without expensive dermatological procedures! Here are practical tips to reduce the risk of having toasted skin during the cold season. ✅ Maintain distance Heed the manufacturer-recommended clearance from the heater. Avoid placing legs within the direct stream of an infrared radiant heater for extended periods of time. ✅ Limit exposure Don’t let any one skin area be exposed to concentrated heat for hours every day. If you need to be near the space heater, rotate your exposed area frequently so that no single part of your body is always facing the heater. ✅ Use barriers A thin layer of clothing or a blanket helps reduce direct radiant exposure. When to See a Doctor Consider seeking professional medical help if: The discoloration doesn’t begin to fade after stopping heat exposure. The affected skin becomes ulcerated, firm, or forms a lump. The lesion is painful, bleeds, or has fast changes in color/texture. Any of these warrant dermatological assessment and possibly a biopsy to exclude other skin diseases or rare malignant changes. Takeaway “Space heater rash” or toasted skin syndrome isn’t just a cosmetic issue — it’s the skin saying “I’ve been roasted too often.” The fix is simple: stop the chronic heat exposure. At Total Home Supply, we always tell our customers to practice safe distance and time limits when using space heaters. And for stubborn or suspicious patches, we recommend consulting a dermatologist — early removal of the heat source usually prevents progression and reduces the chance of long-term pigment changes. Stay warm and safe this fall! Mickey Luongo Mickey is the resident heating and air conditioning expert with over 15 years of experience in the industry.
