A high-profile dermatologist has posted a video warning people of the health risks of repeatedly placing their laptops on their thighs.
Heath professional Daniel Sugai who has more than 575,000 followers on TikTok, where he says the common habit can cause Erythema ab igne.
"Texting a friend to stop using their laptop on their lap/thighs as it is causing a condition called Erythema ab igne (caused by chronic heat exposure) that can be permanent," the post read on his Instagram.
Erythema ab igne, meaning “redness from fire” in Latin, is a condition caused by chronic heat exposure and according to Dr Sugai, can happen through other ways as well.
"Laptops can do this but also heating pads for chronic pain (back pain, abdominal pain, and endometriosis), heated car seats and space heaters!" he said on Instagram.
"It can be reversible if the heat source is stopped early enough but hyperpigmentation can be permanent."
"This is not medical advice — see your derm for a formal diagnosis!"
Dermatologist answers questions about Erythema ab igne
Professor in dermatology, Saxon Smith of The Dermatology and Skin Cancer Centre, told Yahoo News Australia that he was glad social media is bringing awareness to this skin condition that causes a "net-like" pigmentation.
"It’s a condition we’ve known about for a very long time and how it’s been caused has just changed based on technology," Professor Smith said.
"Historically it used to be in relation to exposure to electric heaters — bar heaters in 70s and 80s — on our lower legs.
"More modernly we’re starting to see it now when people leave their laptop on their chest or on their tummy."
How likely is it to happen?
While we've all likely done it, it's only the "constant exposure to the heat from the battery and laptop that causes it".
"We really aren’t just talking about whether you have a hot wattle bottle on a couple of times a month or your laptop on your chest every odd day," Professor Smith said.
"We’re talking about daily repeated exposure over and over to the same localised area on the body."
While dermatologists don't know how long exactly the heat takes to start generating the condition as "it's always different," Professor Smith thinks it "has to depend on some sort of genetic predisposition".
Does Erythema ab igne only occur through direct exposure?
Because it’s just formed by heat, according to Professor Smith, the condition "can be generated directly by having the contact on skin without any clothing but also through clothing".
"Obviously if you have multiple layers of clothing, particularly in the long cold winter we’ve had, it would take longer exposure as the layers can be somewhat protective," Professor Smith said.
"Even if you’re typing away with your pyjamas on, it’s not going to protect you."
He also expanded on Dr Sugai's point about the skin condition sometimes being permanent.
"Certainly in the earlier phases the condition is reversible by stopping the process which is causing it," he said.
"However the longer it’s there for the less likely the skin will recover completely."
Long term exposure can lead to skin cancer
The longer the condition is on the skin for, the more likely it is to cause other problems.
"The skin can break down and cause ulcerations, and long-term there’s a risk you can have skin cancer formation because of the chronic inflammation and change in the skin, if you don’t intervene earlier," Professor Smith said.
He said that it's "just about being aware of what you’re doing" and seeking medical assistance if you do experience skin discolouration if you don't know what's causing it.
Social media users react to dermatologist Daniel Sugai's video
The video seemed to resonate with many viewers, as some said they were guilty of doing this and shared their experiences.
"Oh wow! It’s a thing! I live in a cold climate and would blast a space heater under my desk," one person said on Instagram.
"Have some minor permanent impact from it for sure!"
"I got this from using a heating pad on my back constantly," another said. "It was more of a splotchy darkening of the area."
"I did this to the back of my legs from the seat warmer in our vehicle," a third person said.
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