Hair Liberty’s Nicole Harmon, our Resident Curl Chemist, is answering your most urgent hair questions. Got one for her? Email me at [email protected] using “Hair Liberty” in the subject line and she may answer your question right here on the blog.

What is deep conditioning?

“Deep Conditioning” is often suggested as a remedy for dry or damaged hair. The goal of deep conditioning is to strengthen damaged hair and prevent breakage. To deep condition you must use a conditioner that contains ingredients that can absorb into the hair strand. Examples of penetrating ingredients include hydrolyzed protein, amino acids, cetrimonium bromide, panthenol and some silicones.

Does deep conditioning require heat?

No, it’s a common myth that deep conditioning requires heat. If a conditioner works with heat, its instructions will tell you to apply heat for a specific amount of time. Heat will only increase the effect of a conditioner if it has been formulated with penetrating ingredients. Conditioners that require heat don’t work better than conditioners that tell you to apply and rinse after a few minutes. It all depends on the ingredients.

I like sitting under the dryer. Is there any harm?

Yes, sitting under a bonnet dryer for long periods of time with conditioner in your hair can cause harm. The instructions on your conditioner tell you the safest way to use the product. Studies show that preservatives and other chemicals in cosmetic products can cause eczema and a type of alopecia called telogen effluvium.

We’re used to thinking of eczema as a skin condition that runs in families, but frequent exposure to cosmetic chemicals can cause a type of eczema called “acute contact dermatitis”. Symptoms of acute contact dermatitis include itching, bumps, tenderness, and dry patches. Studies show that acute contact dermatitis on the scalp leads to a form of short-term alopecia called telogen effluvium. The condition causes excess hair shedding for up to 6 months.

When you leave a conditioner on longer than the recommend time you may be increasing your exposure to cosmetic chemicals that have been linked to eczema, alopecia, and more serious health problems like cancer. Adding heat increases your exposure even more.

Can I sit under the dryer if I only use natural/organic products?

It will always be safest to follow the instructions on your conditioner. Just because a product is labeled “natural” or “organic” doesn’t mean it’s safer than anything else. Some natural ingredients cause more allergy problems than synthetic ingredients. There are also loopholes in FDA guidelines that allow manufacturers to omit certain ingredients from the label. The manufacturer is the only one who knows exactly what’s in the bottle and whether it’s safe or not to use the product with heat.

I think I have contact dermatitis on my scalp and excess shedding. What do I do now?

1) Make a decision today to follow the instructions on your products. Don’t leave in rinse-off products and don’t let rinse-off products sit on your scalp for long periods of time.
2) Visit a Dermatologist or Trichologist for a scalp evaluation if possible.
3) Don’t scratch your scalp when it itches. Micro-cuts on the scalp can lead to bacterial infections.
4) Be patient. Itching, bumps, and the other symptoms of acute contact dermatitis usually go away within 4 weeks after the exposure stops. Excess shedding due to telogen effluvium should stop within 6 months.
5) For extra softness and easier detangling when you wash your hair, do a pre-shampoo oil treatment each week.


AetnaInteliHealth. Health A to Z: Eczema. Available at

Antonella Tosti; Bianca Maria Piraccini; Dominique J. J. van Neste. Telogen Effluvium After Allergic Contact Dermatitis of the Scalp. Arch Dermatol. 2001;137(2):187-190.

CW Hughes, E. Telogen Effluvium. Medscape Reference. Available at

Environmental Working Group. 2008. Study: Almost Half Of All ‘Natural’ Personal Care Products Contain Known Carcinogen. Available at

Flyvholm MA, Menné T. Allergic contact dermatitis from formaldehyde. A case study focusing on sources of formaldehyde exposure. Contact Dermatitis. 1992 Jul;27(1):27-36.

Toribo, J., et al. “Allergic Contact Dermatitis In A Girl Due To Several Cosmetics Containing Diazolidinyl-Urea Or Imidazolidinyl-Urea.” Contact Dermatitis (01051873) 63.1 (2010): 49-50.

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