Heat protectant: how it works and how to use it

A blow dryer, flat iron or curling iron can make hair brittle, frizzy and dull over time. A heat protectant can help reduce that damage, but it cannot make heat harmless. How you use the tools matters just as much as what you spray on first.

Quick answer: Heat protectant is a spray, cream or serum that coats hair before heat styling. Apply it to damp hair before you blow-dry, let hair dry fully before a flat iron, use the lowest heat that gives the style, and keep tools moving. It lowers damage but does not remove it, so use hot tools less often.

What does heat do to hair?

The American Academy of Dermatology (AAD) says that no matter your hair type, excessive heat can damage hair. Heat styling can make hair look brittle, frizzy and lackluster, and in some cases hair can break off or fall out.

A small laboratory study on hair samples found that surface damage to the hair increased as the dryer temperature went up. In that study, a dryer held about 15 cm (6 inches) from the hair and kept moving caused less damage than drying hair naturally, but hair dried at a very high temperature held close showed the most damage. It was a small test on hair samples, so real-life results may differ.

How does a heat protectant work?

Heat protectants are cosmetic products. Many contain silicones and film-forming ingredients, which are polymers that leave a thin coating on the hair. The idea is that this coating makes it harder for heat to reach the hair inside and helps the hair stay smooth. Many also include conditioning ingredients that cut down on friction and frizz.

The AAD advises using a heat protecting product before styling and says that adding it to wet hair before styling helps minimize heat damage. Notice the word "minimize." A protectant lowers damage; it does not stop it. For a closer look at the problem it addresses, see heat damage and breakage.

How to apply heat protectant

1. Wash and condition your hair. Use a conditioner after each shampoo, as the AAD advises.
2. Gently squeeze out water or wrap your hair in a towel. Rubbing with a towel is a damaging habit, says the AAD.
3. Apply the protectant to damp hair, from mid-lengths to ends, where hair is oldest and most fragile. Comb it through with a wide-tooth comb.
4. Let hair air-dry partly before blow-drying. The AAD suggests allowing hair to partially air-dry before you style.
5. Blow-dry on a low or medium setting, keeping the dryer moving and a few inches away from your head (the lab study above used about 15 cm, or 6 inches).
6. Use a flat iron or curling iron only on dry hair. The AAD says flat irons should be used on dry hair on a low or medium heat setting. Check your product label: some protectants are made for damp hair, some for dry hair, and some for both.

Browse heat protectants and leave-in products to compare formulas for your hair type.

Settings and technique

The AAD does not give exact temperatures, so there is no number you can rely on for every hair type. Instead, follow these guidelines from the AAD pages:

• Use a flat iron on a low or medium heat setting, and use the lowest temperature that gives you the style you want.
• With a curling iron, leave it in place for only a second or two.
• Work in small sections so you do not need many passes.
• Blow-dry less often during the week to limit damage.

Fine, bleached or already damaged hair is more fragile, so use the gentlest settings. See fine, flat hair and dry and damaged hair for more.

How often is too often?

The AAD gives two different limits on its hair pages. One page says flat irons should be used no more often than every other day. Another page about habits that damage hair suggests using hot tools only about once a week, or less. If your hair is thin, dry, bleached, curly or already breaking, it makes sense to aim for the lower end.

Common mistakes that still damage hair

Other ways to protect your hair

• Air-dry when you can, and use the lowest heat setting when you do not.
• Space out coloring. The AAD suggests waiting longer between color touch-ups and having only one of coloring, relaxing or perming at a time.
• Avoid tight hairstyles that pull on hair, such as tight ponytails or braids, which can cause breakage.
• Moisturize regularly with conditioner. If you see more frizz, frizz has more ideas.

When to see a dermatologist

• Your hair breaks off in clumps, or you see bald or thin patches.
• You notice more shedding than usual. The AAD says seeing a dermatologist is especially important if you are worried about thinning hair or hair loss.
• Your scalp is burned, blistered, sore or very itchy.
• Changing how you style and care for your hair does not help it look healthier.

FAQ

Does heat protectant protect from the sun?

Not unless the label says so. The AAD mentions leave-in conditioners with zinc oxide as an option for sun exposure; check the label.

Can I use oil as a heat protectant?

Choose a product labeled as a heat protectant, which is what the AAD recommends using before styling.

Is air-drying better than blow-drying?

The AAD suggests air-drying when you can, but the small lab study above found that a dryer held at a distance and kept moving caused less damage than leaving hair wet for a long time. Gentle, partial air-drying followed by low heat is a sensible middle path.

Do ceramic tools make protectant unnecessary?

No. The AAD still advises a heat protecting product and the lowest setting that works.

Sources

• Hair styling without damage (American Academy of Dermatology)
• 10 hair care habits that can damage your hair (American Academy of Dermatology)
• Black hair: Tips for everyday care (American Academy of Dermatology)
• Hair shaft damage from heat and drying time of hair dryer (Annals of Dermatology, via PubMed Central, NIH)