Your Skin Hates Heat

New research suggests UV rays may not be the only damaging element to protect yourself from this hot season.

Portrait of Tammy Strobel

New research suggests UV rays may not be the only damaging element to protect yourself from this hot season. 

Skin’s enemy number one is the sun. You know that. But your hair dryer? Your workout? Science now shows that heat can also wreak some serious havoc. “I knew something was up when my patients with melasma, who swore they were slathering on sunscreen and fading creams religiously and staying out of direct sunlight, found the dark patches and blotchiness on their faces were getting no better,” says Shasa Hu, a dermatologist in Miami and a member of the Dr. Brandt Skin Advisory Board. “The more I looked into it, the more it became evident that regular exposure to high temperatures appeared to be inducing oxidative damage and boosting melanin production in a way that was very similar to how UV rays cause hyperpigmentation.” For years, dermatologists have talked about the damage linked to UVA and UVB rays. “It’s as if someone roped off just those two wavelengths from the rest of the cascade of light. But we are also regularly exposed to visible light and infrared radiation [which heats the skin] and are just now starting to understand that the whole spectrum affects the skin,” says Neal Schultz, a derma tologist in New York City. 

So what is happening physiologically? “One theory is that heat causes blood vessels to dilate, which ups inflammation and triggers melanocytes to produce more pigment,” says Marie Jhin, a dermatologist in San Carlos, California. This heat-pigment link may be one reason why some patients suffer hyperpigmentation after laser treatments; people whose skin tone has more pigment (typically those of Asian, His panic, Indian, and Middle Eastern descent) and everyone with melasma seem most vulnerable. 

Extra pigment, however, is not the only marring experts believe we sustain from heat exposure. After studying the topic for almost a decade, researchers at Seoul National University College of Medicine say it can also inhibit the skin’s ability to protect and repair itself. Heat can lower antioxidant levels and raise proteins that break down the skin’s spongy collagen supply, causing fine lines and sagging. A study published last April in the Journal of Drugs in Dermatology that tested the efficacy of a sunscreen (SkinMedica Total Defense + Repair SPF 34) reached similar conclusions about heat and skin. 

Heat may also lead to a “compromised barrier function, which can cause chronic irritation of the skin,” says Carl Thornfeldt, a dermatologist in Fruitland, Idaho, and the founder of Epionce skin care. Several doctors cited the condition erythema ab igne, sometimes referred to as “hot water bottle rash” and “toasted skin,” as an extreme result of long-term or frequent exposure to infrared radiation. Usually characterised by red, mottled, lacy-looking skin, erythema ab igne typically develops after weeks of direct heat exposure. “We are talking about direct contact of about 45 degrees Celsius, so not enough to burn your skin but enough to really heat it up,” says Dr Hu, who points to a heating pad or a laptop placed on your thighs for hours as common causes. Erythema ab igne is extreme irritation caused by heat, but Dr Hu believes the same inflammatory response can cause less severe damage too, such as broken blood vessels, sensitivity, and a worsening of inflammatory conditions like rosacea, acne, or psoriasis. 

Now for some good news. “Some of what you’re already doing to protect your skin from UV rays may help minimise the impact of heat as well,” Dr Jhin says. “Physical sunblocks that contain zinc or titanium dioxide can help quell heat’s temperature- raising impact because they act like a wall, bouncing light and heat off the skin.” On the other hand, chemical sunscreens (such as those containing oxybenzone or avobenzone) absorb rays, which heats up the skin, Dr Jhin says. In addition to wearing a broad- spectrum physical sunscreen, apply a mineral foundation to boost the heat-blocking effect of its SPF, Dr Jhin adds. 

Your behaviour plays a role too. “If you care about the condition of your skin, you will have to make compromises – maybe you work out but skip the steam room. Or reduce your beach time from six hours to two,” Dr Hu says. The effect of heat is cumulative, so cutting down on exposure will decrease damage too. 

You can also temper the effects of heat by taking a cool shower or spritzing yourself with cool water. “This enables a quicker recovery than if you just let your skin regulate itself,” Dr Hu says. Working from the inside out may help as well, says Dr Thornfeldt, who suggests upping your intake of anti- inflammatory and cooling food and drinks, like iced spearmint tea, smoothies, even ice cubes. The reverse is also true – if you’re in a hot environment, don’t compound the effect with caffeine, alcohol, and spicy foods, which boost blood flow to the skin and may magnify inflammation. 

One final tactic: Help your skin help itself. “If you build up your skin’s barrier function with skincare that contains lipids, ceramides, or noncomedogenic oils, you will minimise heat’s ability to disrupt it and cause the inflammation that leads to hyperpigmentation, fine lines, and chronic irritation,” Dr Thornfeldt says. Applying topical antioxidants may also replenish those diminished by heat exposure. Layer an antioxidant serum under your favourite sunscreen each morning, or mix a vitamin C powder into any skincare product to face the day more protected. 


Mineral makeup and shade can shield you from heat-induced damage.

“Your face needs to cool down to stay clear and calm.”