It’s well-known that heat can damage your hair — but it’s still one of the most popular ways to style your hair. Despite the evidence that overheating your hair can cause split ends, dullness, and even hair loss, many people still go hard on the hairdryer, straighteners, and curling tongs .
So what can you do if your hair feels frizzy and fried? Here’s everything you need to know about how to fix heat-damaged hair.
How does heat damage your hair?
To restore heat-damaged hair, it’s important to understand exactly what’s happening when you subject your strands to excessive heat.
Research shows that blowdrying your hair causes the cuticle to crack, damaging the surface of your hair [2, 3].The cuticle protects the hair cortex, which is made up of strands of keratin — the protein responsible for keeping hair strong, shiny, and healthy.
Image showing the basic structure of a single hair strand. Image credit: Hair Know How
Strong, healthy cuticles give your hair its lustrous shine. So when the cuticle is damaged, hair can start to feel dry and frizzy. But does the damage stop there?
Some research suggests that, despite the cuticle damage, the hair cortex remains intact after heat treatment . However, other studies show that excessive heat changes the structure of keratin, and degrades other components within the hair cortex . These changes can cause your hair to lose its natural shape (especially for curly-haired people). They can also lead to breakage, hair bubbling, and weakened hair fibres.
What does heat damaged hair look like?
At a microscopic level, the heat damage to your cuticle is unmistakable. The image below shows 5 levels of cuticle damage caused by 5 different hair drying techniques and temperatures.
Image credit: Hair Shaft Damage from Heat and Drying Time of Hair Dryer
- A: no treatment. The cuticle is relatively flat and unfrayed at the edges.
- B: air drying at room temperature. The cuticle stays flat, though some scratches can be seen on the surface.
- C: blowdrying at 47°c. The cuticle begins to lift, exposing the cortex underneath.
- D: blowdrying at 61°c. More severe lifting and cracking is visible across the cuticle.
- E: blowdrying at 95°c. Cuticle borders are frayed and cracked, with holes developing across the hair surface.
But you don’t need to put your hair under a microscope to see the damage caused by high heats. Individual hair fibre damage can have a big impact on the overall appearance of your hair. Take a look at these images of heat-damaged hair to see for yourself:
1. Hair that has been subject to chemical and heat treatment. The colour has faded, and the strands appear dry and frizzy. Image credit: Amazon.com. 2. Heat-damaged hair is extremely dry, with flyaways caused by breakage high on each strand. Image credit: Medium.com
Natural curls are destroyed by heat treatments, leaving hair limp, straggly, and undefined. Image credit: Youtube.com
But it’s not just heat that can damage your hair. Chemicals, tight ponytails, and even overbrushing can cause dryness and fragility that leaves your hair looking far from its best. So how can you tell if your hair is heat-damaged — or if something else is to blame for your unhealthy tresses?
How to tell if your hair is heat damaged
There are a few telltale signs of heat-damaged hair, including:
- Dull colour — repeated direct heat application (such as from hair straighteners) quickly dulls the pigment in your hair, especially if it’s bleached or dyed
- Rough, dry texture — cuticle damage makes your hair less smooth and shiny, giving your hair a dry, brittle look
- Bubble hair — small “bubbles” appear along the hair shaft as a result of exposure to high temperatures 
- Breakage and flyaways — damaged hair snaps easily, causing shorter hairs that escape when your hair is tied up (these are known as flyaways)
- Unable to retain hair colour — cuticle damage can make hair strands more porous, which makes it difficult to retain colour if you dye your hair. Learn more about hair dye and hair loss.
If you’re still not sure if heat is the culprit, take stock of how you look after your hair. If you wash, blowdry, and heat-style your hair every day, you’re probably subjecting it to far too much heat on a regular basis. Also remember that higher temperatures cause more damage, so consider dialling down the temperature on your hair straighteners or curling tongs.
Can heat damage be reversed?
Heat damage is irreversible — so once your hair cuticles have been damaged, there’s no going back without heading to the hairdresser.
Heat causes hair to lose its elasticity, so your strands are more likely to snap and fray, resulting in split ends (medically known as trichoclasis). As the damage moves up the hair shaft, the issues become more visible and more difficult to control without cutting your hair. So to keep your hair looking healthy, it’s important to get it trimmed regularly to remove your split and damaged ends.
Can heat-damaged hair cause hair loss?
Heat damage isn’t a direct cause of hair loss, but it can give the appearance of thinning hair. As more strands snap, your hair loses volume. This may give the illusion of hair loss, even if you haven’t actually lost any hair from your follicles.
Because heat dulls the hair, you may also find yourself dying or bleaching your hair more frequently. Overuse of hair dye chemicals like ammonia and ethanolamine can irritate the scalp and cause further damage to your hair strands, leading to even more breakage . One study also found that chemically active hair dyes may cause direct hair loss, so it’s essential to avoid exposing your hair to these harsh substances .
How to fix heat-damaged hair
While you can’t reverse heat damage to your hair, there are things you can do to prevent further damage, and create smoother, shinier locks.
Go for a trim
Cutting off your damaged ends is the single best way to fix heat-damaged hair. It stops hair damage from advancing and snapping off higher up your hair strands. By removing your straggly ends, your hair will also look thicker and more voluminous. For best results, make a regular trip to the salon part of your haircare routine.
Use deep conditioning treatments
Leave-in conditioners and hair masks can make your hair look much smoother. Coconut oil and argan oil are particularly effective at moisturising your hair, and protecting it from further damage [8, 9].
Use fewer heat styling products
If you can, give your hair a break from heat styling for a few weeks, or even longer. This will give healthy new hair a chance to grow through. If you can’t resist completely, try to reduce the amount of time you subject your hair to hairdryers, straighteners, or curling tongs. Even better, use these implements at the lowest possible temperature.
What temperature should you style your hair at?
Higher temperatures cause more damage to your hair cuticles . So how hot is too hot for styling your hair?
Jonathan Colombini, haircare expert at L’Oréal Paris, says it depends on the coarseness of your hair . People with naturally fine hair should stick to lower temperatures of around 170°c when using hair straighteners or curling tongs, while those with thicker hair can stretch to 200°c.
You should never use the hottest setting on your hairdryer. Stick to low/medium settings, and blowdry your hair downwards. This helps keep the cuticles flat, so your hair looks super smooth for as long as possible.
How to protect your hair from heat damage
Prevent future heat-damaged hair with these tips:
- Get your hair cut regularly to prevent split ends
- Use a good heat protection serum
- Never use hair straighteners or curling tongs on wet hair
- Protect your hair in the sun by wearing a hat or headscarf
- When you blowdry your hair, hold it at a distance of 15 cm from your hair and continuously move the hairdryer — one study suggests this technique can cause less damage than air drying 
- For at least a few weeks, avoid using a hair dryer after a hair transplant.
Is your hair damaged, thinning, or falling out?
It can be easy to confuse heat-damaged hair with hair loss, especially if you’ve noticed significant thinning. Heat-damaged hair doesn’t usually fall out in clumps when you wash it — so if you see more substantial hair loss in the shower or on your pillow, you may be experiencing hair loss rather than hair breakage.
Find out if your hair is thinning and why with a free consultation at the Wimpole Clinic. No matter what’s causing your hair to look dry, damaged, or thin, we’ll help you restore it to its full, shiny best.
- Review on Hair Problem and its Solution
- Heat-damaged evaluation of virgin hair
- The cracking of human hair cuticles by cyclical thermal stresses
- Hair Shaft Damage from Heat and Drying Time of Hair Dryer
- Bubble Hair and Other Acquired Hair Shaft Anomalies due to Hot Ironing on Wet Hair
- Comparison of damage to human hair fibers caused by monoethanolamine- and ammonia-based hair colorants
- Aqueous MEA and Ammonia Sorption-Induced Damage in Keratin Fibers
- Hair Cosmetics: An Overview
- Hair Protective Effect of Argan Oil (Argania spinosa Kernel Oil) and Cupuassu Butter (Theobroma grandiflorum Seed Butter) Post Treatment with Hair Dye
- Are You Flat Ironing Your Hair At The Right Temperature?
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