Swimming and your hair: chlorine, copper and "green hair"

What pool water does

• Chlorine: in a study of Japanese elite swimmers, 61% had hair discolouration, compared with none of the non-swimmers. The researchers thought friction with water damaged the hair's outer cuticle, letting the chlorine-based chemicals in pool water reach inside the hair and break down its pigment.
• Copper and "green hair": green hair isn't caused by chlorine itself but by copper — from pool water or household plumbing — building up in the hair. It's mostly reported in blonde or light hair that's already damaged by sun, bleaching, dyeing or perming, and in poorly maintained pools.

Before and after you swim

The American Academy of Dermatology (AAD) recommends:

1. Wear a swim cap.
2. Rinse your hair straight after swimming.
3. Wash with a swimmers' shampoo and follow with a deep conditioner.

For children, the AAD says pool chemicals should be washed out after swimming: shampoo works best for normal to oily hair, while very dry or tightly curled hair should be rinsed well and conditioned.

If your hair has turned green

A published case report describes green hair fading over about eight weeks with a shampoo containing EDTA (a "chelating" ingredient that binds metals), and suggests a conditioner before swimming to help prevent it. That's a single case, so treat it as a lead rather than a proven fix — a hairdresser can also help.

Not medical advice. This guide is general information from the sources listed, not a diagnosis or a substitute for a pharmacist, GP or dermatologist. If you are worried, or symptoms are severe or not improving, get advice. Read our health information policy.