The heatwave hyperpigmentation mistake you could be making
The real reason your skin reacts in hot weather, and how to fix it
While a heatwave tends to have us changing up all of our routines - from how we sleep to what we make for dinner and even the journey we take for our commute (AC only please) - there's one area we tend to forget about that definitely needs some attention: our skincare routines.
The best vitamin C serums, AHA exfoliants and retinol creams and serums are the backbone of most modern routines, and rightly so. But carrying on with a winter skincare routine straight through a heatwave can be damaging, and using these hardworking actives in a certain way when the sun is at its strongest, can be doing more harm than good, leaving you with the dark patches and uneven tone you were trying to treat in the first place.
"While active ingredients such as Vitamin C, AHAs and retinol can deliver fantastic results, they need to be used carefully during periods of intense sun exposure or a heatwave," says Joanne Evans, Skin Expert & Founder of Skin-Matters. "The biggest concern isn't necessarily the ingredient itself, but what it does to the skin barrier and how vulnerable that can leave your skin when exposed to UV radiation."
The issue is something called post-inflammatory hyperpigmentation, or PIH. Actives work by speeding up cell turnover or exfoliating the skin’s surface, which is brilliant for texture and glow, but it also leaves skin more reactive and less able to defend itself against UV. Add strong sun into that mix and you get inflammation, and inflammation is what triggers melanocytes into overproducing pigment. The result is dark patches that can take months, sometimes longer, to fade. So what can you do to avoid this? We spoke to the experts to find out.
The heatwave hyperpigmentation mistake you could be making
"Many people assume stronger sunshine simply means they need to wear more SPF, but it's equally important to think about what's in your skincare routine," warns Dr Richard Devine, aesthetic doctor and founder of Devine Clinic. "Ingredients such as retinol, AHAs and, in some cases, vitamin C can make the skin more vulnerable if they're not used correctly alongside diligent sun protection. When UV levels are high, this increased sensitivity can trigger inflammation, which is one of the key pathways to post-inflammatory hyperpigmentation."
"If you're already prone to pigmentation or melasma, periods of intense sun exposure are when you need to be particularly mindful of active skincare ingredients," adds Caroline Hall, aesthetic nurse and founder of R&R Aesthetics. "Over-exfoliating with acids or using retinol too frequently can compromise the skin barrier, making it easier for UV radiation to trigger excess melanin production. The result can be dark patches that are far more difficult to treat than they are to prevent.
However, Dr Ginni Mansberg, Founder of ESK Evidence Skincare, explains that these skincare ingredients aren't necessarily "unsafe in summer," adding that "it’s worth separating irritation from photosensitivity. Most of these ingredients don’t actually make your skin burn more easily in the sun. Instead, if they’ve disrupted your skin barrier, UV exposure, heat and sweat can make that irritation feel much worse."
So, what should you be doing instead?
"In the heatwave, you don't need to give any actives up completely, just use them more carefully," advises Kimberley Medd, Head of Clinic at Face The Future. "If your skin is becoming more sensitive, drier or more irritated in the heat, use retinol and AHAs in the evening, and cut back to a couple of times a week. Vitamin C is typically best used in the morning under SPF."
However, Medd also reminds us that it's important to pay attention to the health of your vitamin C serum, explaining that "it's unstable in heat and oxidises easily if not stored correctly - and oxidised vitamin C can irritate skin. If the serum has darkened or changed its texture, it's likely oxidised and should be replaced."
If you'd rather avoid these ingredients altogether when the hot weather hits, Evans has some tips for an alternative skincare routine.
"When temperatures soar, I recommend simplifying your routine and focusing on hydration, barrier repair and calming inflammation," advises Evans. "Look for ingredients such as glycerin, panthenol (Vitamin B5), ceramides, ectoin, niacinamide, probiotics and soothing botanical extracts. These help strengthen the skin barrier, reduce redness and keep the skin resilient without increasing sensitivity.
"Hyaluronic acid is great as the heat can cause the skin to become very dehydrated - my favourite is the Bio Effect EGF Serum. I also always recommend my Skin Matters Calming Gel as this multitasking gel works beautifully as a daily hydrator or an overnight calming mask to support radiant, resilient summer skin."
The most important thing? According to Hall, it's to "never underestimate the importance of daily SPF, hats and seeking shade where possible."
Your heatwave skincare kit - straight from the experts...
