Heatwave Hair Shedding Is Real—Here’s How a Dermatologist Recommends Protecting Your Hair and Scalp
According to a derm, this year's extreme heat coupled with seasonal patterns may have led to more hair loss than usual
As we turn our back on yet another heatwave, I've started to equate something with them: more strands in my hair brush, and increased shedding in the shower too. Of course, the latter is something that you can expect towards the end of the summer; there is a recognised pattern of seasonal shedding, where strands tend to fall a little more. However, this extreme heat may also contribute to increased hair fall.
First, we have to understand how the hair cycle works. "At any given time, most of your hair, around 85 to 90 per cent, is in the growing phase, while the remaining 10 to 15 per cent is in a resting phase called telogen that ends with the hair being shed," explains Dr Aamna Adel, Consultant Dermatologist and founder of haircare brand, rhute. "A study of more than 800 women found that the proportion of hairs in this resting phase peaks over the summer, and because that phase lasts roughly three months, those hairs are then released a few months later, which is what leads to the shed in late summer and autumn."
This is due to several factors. It's thought to be driven by seasonal cues, like summer UV, changing daylight, and their effect on hormones like melatonin, the dermatologist notes. And of course, a few months of sun, heat, seawater, and chlorine can leave hair more fragile, so natural shedding can feel more substantial than it actually is.
How Do Heatwaves Affect Hair?
So, how do the many heatwaves we've experienced this summer factor in? Well, rather than making the hair fall from the root in the way a big physical stressor does, extreme heat can damage the hair fibre and put the scalp under strain. This adds breakage and can make the overall loss look and feel worse.
"UV degrades keratin, which is the main structural protein in hair, and that leaves the fibre weaker, drier, and more prone to breakage and split ends, while also breaking down the pigment so colour fades faster," says Dr Adel. "The scalp is skin, so it can burn and become dry, irritated, or inflamed, none of which makes for a happy environment for the follicles. Chemically treated or bleached hair is affected the most, because the cuticle is already compromised and less able to protect the inner part of the hair."
TLDR? " A summer of heatwaves tends to leave hair in poorer condition going into the natural autumn shed, which makes it more of an aggravating factor layered on top rather than the root cause."
How Much Shedding Is Normal During the Summer?
If you've noticed more shedding during this time, the expert advises not to panic. If it is seasonal, remember it's temporary and tends to settle on its own as the follicles move back into their growth phase. "You can't really switch it off, as those hairs committed to shedding months earlier, but you can make sure your scalp is in good shape for the regrowth that follows, and avoid piling other triggers on top."
Losing somewhere between 50 and 100 hairs a day is completely normal, so don't fret if you see more hair in your brush or drain—it's just part of the cycle.
"What I'd pay attention to is a real, sustained change from your own baseline, so noticeably more hair than usual over weeks and months, more scalp showing through, or a ponytail that feels distinctly thinner," Dr Adel explains. "Seasonal shedding should be a modest, temporary increase that settles. The things that suggest it's more, and worth seeing someone about, are hair coming out in patches, shedding that carries on past three or four months, hair that isn't growing back, or shedding alongside other symptoms like fatigue or changes in your periods. Those can point to something like iron deficiency or a thyroid issue."
How to Look After Your Hair in Summer, Going Forward
This is where supporting your scalp environment helps, says the derm, so use ingredients that encourage the hair to stay in its growth phase for longer. She recommends rhute's Density + Repair Scalp Serum, enriched with peptides to support the follicle and help reduce shedding.
"But, it's also important to be honest with yourself about whether something else might be contributing," she adds. "Stress, a recent illness, rapid weight loss, or a low-protein or restrictive diet can all cause shedding through the same pathway and mimic the timing of a seasonal shed."
Prepping for next year is key too, as hair shedding and scalp health are never a quick fix. When it's warm out, ensure you're protecting your hair by wearing a cap and using SPF on the scalp and lengths. Otherwise, opt for a daily serum to look after the barrier, and on the lengths, prioritise gentle hydrating shampoos and conditioner that have volume-boosting effects, as well as a bond-repair treatment. Per the derm, this can help undo some of the sun and chlorine damage, if you have it.
"I'd also look at the basics from the inside, particularly your protein intake and your iron and vitamin D levels, as these often sit behind shedding, and vitamin D in particular tends to dip as the daylight fades into autumn," she concludes. And again, if the shedding is heavy or persistent, you should see a professional. The right treatment always depends on determining the actual cause behind it all.
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