Chlorine effects on hair


I have begun swimming four to six times a week, and am concerned about the effects that chlorine will have on my hair. I have been washing it after each swim with "Ultra Swim," which claims to render the chlorine molecules harmless. I sometimes also use the conditioner by the same brand, but either way, my hair feels "coated" afterward. A friend said I should wear a swimming cap, but my head is too big for the caps I've been able to find in local stores. How concerned should I be about this? Do you have any suggestions?

— G.L.

Dear G.L.,

It seems ironic that wetting your hair in the swimming pool could leave it so dry, but as it turns out, the structure of hair is vulnerable to drying agents such as the chlorine in swimming pools. The cortex, or inner layer, of hair is protected by the cuticle, or outer later. Sebum is a natural lubricant that protects the cuticle. The chlorine in pools sucks the sebum out of your hair, which may cause the cuticle to crack. This damage causes your hair's natural sheen to diminish, and the unprotected cortex to potentially "split," creating split ends.

So why is there chlorine in swimming pools anyway? Well, the strong-smelling element kills bacteria in the water used in swimming pools. Beyond that, chlorine has many functions—in fact, it's one of the most commonly manufactured chemicals in the United States. Chlorine is used in tons of industry and household products such as pesticides, rubber, solvents, paper, and cloth. It's also used as part of the sanitation process for industrial waste and sewage. 

Unfortunately, as you’ve noticed, extended exposure to chlorine can damage your hair. Not only does it dry out your hair, it can also have an effect on your hair color, especially if you’re swimming in an outdoor pool. One study tested the effects of chlorine on different hair colors (both bleached and unbleached/natural) in two different environments: under UV rays (to mimic the sun in an outdoor pool environment) and without UV rays (to mimic the environment of an indoor pool). The study found that, overall, hair damage from the chlorine in swimming pools increased significantly in the presence of sun radiation. Not only did the combination of UV rays and chlorine damage the hair color, but the hair proteins as well. In the presence of UV rays, naturally dark hair became more red and yellow, whereas bleached hair became less red and yellow. Without UV rays, both light and dark hair (natural and bleached) became lighter and more yellow. However, naturally dark hair still became more red without UV rays, and bleached hair still became less red. Despite these findings, more research is still needed to better understand why these changes in hair color and, in the case of sun radiation exposure, hair proteins occur.

Swimmers who want to protect their shiny locks from chlorine induced changes may take the following precautions:

  • Go light on hair coloring, perms, waves, hot curlers/combs, and blow dryers.
  • Wear a rubber bathing cap. Although it doesn't keep all of the water out, it helps. You mentioned having trouble finding one that fit your size. Sports stores or online stores that sell swimmers' equipment often have caps in a wider range of sizes, or you could speak to a store employee about getting a cap specially ordered.
  • Before putting the bathing cap on, put conditioner in your hair. After swimming, rinse hair with tap water, preferably using shampoo.
  • To dry hair, don't rub. Pat or squeeze gently or wrap in a towel. Blow dry your hair on medium or cool settings.
  • Use a wide-tooth comb, not a brush, to detangle wet hair.

The "coated" feeling that you're experiencing in your hair from the swimmers' shampoo and conditioner is probably exactly that—a protective coating from the hazards of chlorine. Try using the swimmers' conditioner under the bathing cap while swimming, and then shampoo and condition it out afterwards with a brand that doesn't coat your hair. Alternating shampoos you use may help combat the buildup of shampoo residue that could be making your hair dull and lifeless. For dry hair, a protein shampoo labeled with substantive protein is recommended, as it is more than slightly acidic. Another option is to rinse your hair with white vinegar and water or lemon and water after shampoo. This acid rinse will help restore the natural shine to your hair.

Swimming is an excellent way to stay physically active, and it can have quite the toll on your hair—taking the necessary steps to protect your tresses will allow you to dive back in worry-free!

Last updated Nov 11, 2022
Originally published Dec 04, 1995

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