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Jul 18, 2023

5 Side Effects of Chlorine On Your Body

Oleg Breslavtsev / Getty Images Chlorine is a chemical disinfectant added to swimming pools to kill germs. In its original gas form, chlorine is a highly irritating and damaging chemical. When added

Oleg Breslavtsev / Getty Images

Chlorine is a chemical disinfectant added to swimming pools to kill germs. In its original gas form, chlorine is a highly irritating and damaging chemical. When added to pool water, chlorine technically turns into the chemicals hypochlorous acid and hypochlorite anion, which disinfect water and is considered safe in the right concentration.

That said, frequent swimmers may find that chlorinated water causes unwanted side effects. When chlorine concentration is too high, it can also cause allergy-like symptoms. Here are five ways chlorine can affect your body.

Adding a chlorine concentration of at least 1 part per million (ppm) to pool water—and 3 ppm in hot tubs—is considered safe by the Centers for Disease Control and Prevention (CDC).

In the U.S., most local health departments require pools to have a combined chlorine level of 0.4 ppm or less. Combined chlorine is chlorine that has already bound itself with germs and waste to disinfect the pool.

Chlorine and other chemicals in pool water can irritate and dry out the skin. People can't be allergic to chlorine, but you can be sensitive to the chemical and have skin reactions that are actually irritant dermatitis caused by hypersensitivity to chlorine.

Chlorinated water can cause irritating skin symptoms like:

Research shows that frequent swimmers are more prone to allergic contact dermatitis or "pool water dermatitis." This itchy rash is caused by pool chemicals like chlorine. However, some people may get rashes from swim gear like swim caps and goggles rubbing on the skin.

If you have psoriasis, an autoimmune skin disorder that causes thick patches of discolored skin and silver scales, dipping in the pool can further aggravate your psoriasis plaques. Chlorine can also worsen symptoms of eczema, a skin disorder that causes dry and itchy patches of skin.

If your skin is sensitive to chlorine, the American Academy of Dermatology suggests:

Chlorinated water dissolves oils that coat and protect your hair, which may make your hair more prone to damage and dryness. Chlorine also breaks down proteins in your hair, increasing your risk of hair breakage. People with white or blonde hair are more at risk because the hair has less melanin (what gives skin and hair color) to protect it.

Chlorine can also lighten your hair, especially if the pool water you swim in has a high concentration of chlorine. (For context, bleach, known to lighten hair and laundry stains, is made with chlorine.) Lightening hair requires high chlorine concentrations, so it takes time and lots of swimming to see the effects. However, UV light from the sun can also lighten hair and increase the impact of chlorine on hair.

To keep your hair healthy while you swim, the AAD suggests you:

Oxidized copper is what turns blonde or white hair green after a swim. Copper sulfate is sometimes added to pools to control algae growth. Copper can also leak into the pool from plumbing or copper ionizer equipment. Chlorine corrodes copper that sticks to the hair, resulting in a similar green-blue color of copper patina.

High levels of combined chlorine release chloramines into the water and air, which can be highly irritating. Combined chlorine is chlorine that has bound to germs and waste to disinfect the pool.

Chlorinated pools don't usually cause respiratory problems. However, if a pool has built up high levels of chloramines, you can experience respiratory issues like:

Pools build up chloramines when chlorine mixes with sweat, dirt, poop, pee, and dead skin cells. Even jumping in the pool with deodorant or makeup can create chloramines.

Chloramines also turns into gas around the pool area. A pool that has built up too many chloramines often has a strong chemical smell, which people mistakenly call a "chlorine smell." The chloramines in the air are usually responsible for respiratory issues during or after swimming. This is more common in indoor pools because they are not as well-ventilated to allow chloramine to leave the area.

Chlorine and other pool chemicals can wash away the thin layer of tears that coat your eyes. As a result, chlorine can cause eye side effects like:

Chloramines released when chlorine combines with human waste also irritate the eyes. Swimmers in a pool with built-up chloramines may experience eye irritation like red, itchy eyes.

The American Academy of Ophthalmology suggests rinsing your eyes with fresh water after swimming to help remove chlorinated water from your eyes. Eye drops may also help rebalance any tears, and wearing goggles keeps chlorinated water out of your eyes.

Chlorine and other pool chemicals can cause people's teeth to form yellow and brown stains, known as swimmer's calculus. This staining happens because the pH of chlorinated pools is higher than your saliva, which breaks down proteins that protect teeth from straining and tartar build-up. Chlorinated pools can also erode enamel, which makes you more likely to deal with staining.

However, it's unlikely your teeth will turn yellow after visiting your local pool a few times a week. Research shows competitive swimmers and divers—especially those who spend more than six hours a week in the pool—are more likely to develop yellow teeth.

U.S. Masters Swimming recommends brushing your teeth before swimming to help prevent pool chemicals from building up on plaque. After a swim, rinse your mouth with fresh water or fluoride mouthwash to help restore your mouth's pH levels. Brushing may be too harsh on your enamel after a swim.

Chlorinated water is considered safe when pools have the correct concentration of chlorine. However, some people are more sensitive to chlorine. Chlorine can irritate the eyes, skin, hair, and teeth.

Occasionally swimming doesn't cause significant side effects, but people who swim frequently are more likely to experience chlorine side effects.

Pools with too high chlorine levels and built-up chloramines can also irritate the respiratory system. If you have issues breathing or have intense allergy-like symptoms, ask the pool manager to check the chlorine levels.

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National Eczema Association. Swimming with eczema: What you should know before you take the plunge.

American College of Allergy, Asthma, & Immunology. Chlorine “allergy”.

American Academy of Dermatology. 10 skin care habits that can worsen acne.

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National Psoriasis Foundation. Taking care of your skin in summer.

American Academy of Dermatology. Will swimming in a pool trigger my child’s eczema?.

American Academy of Dermatology. Must-try summer hair care.

American Academy of Dermatology. Tips for healthy hair.

Water Quality & Health Council. Green hair caused by copper, not chlorine — Myth busted.

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American Academy of Ophthalmology. What you should know about swimming and your eyes.

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U.S. Masters Swimming. How can I keep my teeth white as a swimmer?.