What Is Chlorine Rash?

Chlorine rash is a red, itchy rash that appears within hours of swimming in a chlorinated pool or soaking in a hot tub. Although some people refer to it as a "chlorine allergy," chlorine rash is actually a non-allergic skin reaction, called irritant contact dermatitis, that occurs when a substance damages the skin's protective outer layer.

This article looks at the symptoms, causes, and treatment of chlorine rash as well as conditions with similar features. It also offers tips on how to avoid this irritating skin reaction.

Symptoms of Chlorine Rash

Chlorine rash can happen whenever you have spent time in chlorinated water. It typically appears within a few hours of swimming in a chlorinated pool or soaking in a chlorinated hot tub.

Symptoms of a chlorine rash include:

• Skin redness and swelling
• Skin tenderness and/or itchiness
• Skin rash or patch-like lesions
• Skin dryness, scaliness, or crusting

Chlorine rash is not contagious. The symptoms are self-limiting, meaning that they won't progress after the first day provided you stay out of the pool.

Causes

Chlorine rash is a type of irritant contact dermatitis. It is a condition caused by chemicals that irritate the skin, including solvents, detergents, and disinfectants.

Unlike a skin allergy, which is caused by a hypersensitive reaction to a substance it regards as harmful, irritant contact dermatitis occurs when the skin barrier is disrupted by a substance that triggers inflammation in underlying cells.

Chlorine is a strong chemical additive used to keep pools and hot tubs safe from algae, bacteria, and other microbes. However, when soaking in chlorinated water, two things can occur:

• Firstly, the skin becomes increasingly porous the longer you soak.
• Secondly, chlorine strips away the protective oil on the skin, called sebum, allowing the chemical to seep into the underlying cells.

When this occurs, the underlying cells will react to the harsh and damaging chemicals. The body's response to this is inflammation. With inflammation, the body will release immune chemicals that help protect and heal cells but also cause redness, swelling, itching, and other symptoms.

Some people are also more sensitive to chlorine than others, including those with eczema or psoriasis. Both of these conditions cause scaly, disrupted skin that provides chlorine easier access to underlying cells.

The risk of chlorine rash increases if chlorine levels in the water are high. But, it can also occur with mildly chlorinated water when ammonia found in sweat and urine combines with chlorine to create a harsh chemical known as chloramine. This risk of this chloramine is especially high in public pools.

Chlorine Rash vs. Swimmer’s Itch

There are other rashes you can get from swimming beside a chlorine rash. One type is popularly referred to as swimmer's itch.

Also known as cercarial dermatitis, swimmer's itch is caused by an allergy to a microscopic, worm-like parasite that infects some birds and mammals. The larvae of the parasites, called schistosomes, are released from infected snails into fresh and salt water (such as lakes, ponds, and oceans). The larvae then burrow their way into water-exposed skin.

Symptoms of swimmer's itch tend to progress in a specific way and may include:

• Skin tingling as the parasite burrows into the skin
• The development of pinhead-sized spots
• The eventual outbreak of skin redness or rash
• Mild to severe itching

Scratching only makes the symptoms worse and can lead to pain and scarring.

As with chlorine rash, swimmer's itch is not contagious.

Other Conditions That Mimic Chlorine Rash

There are several other conditions that cause chlorine rash-like symptoms:

• Hot tub folliculitis: Also called hot tub rash, this condition is caused by a bacteria known as Pseudomonas that thrives in warm water and is resistant to chlorine. Hot tub folliculitis causes itchy, pus-filled bumps that tend to be worse in areas covered by a swimsuit. The rash usually goes away without treatment after a few days.
• Miliaria: Also known as heat rash, miliaria is caused by blocked sweat glands and trapped sweat beneath the skin. It can occur after swimming if you are in the sun and get overheated. Miliaria is most common in hot, humid weather. Symptoms include itchiness with small blistering rashes. Symptoms will resolve on their own once the skin is cooled.
• Cold urticaria: Also referred to as a cold rash, this is a type of hives triggered by sudden exposure to cold. Cold urticaria is due to an abnormal immune response in which fluids rapidly accumulate in the middle layer of skin, causing itchy red welts with well-defined borders. The hives will usually clear on their own within 24 hours.

Treatment

Chlorine rash is typically treated at home with over-the-counter (OTC) medications. Most rashes will clear up after several days with appropriate treatment. This includes avoiding swimming pools and hot tubs until fully healed.

Treatment options, used either alone or in combination, include:

• Hydrocortisone cream is a mild steroid cream applied to the skin that helps temper inflammation and reduces itching, redness, and swelling. The cream is typically applied two to four times a day.
• Benadryl cream is a topical form of the oral antihistamine Benadryl (diphenhydramine). It works by blocking the action of an immune substance known as histamine that causes skin swelling and itching. Benedryl is a good option if the itching is severe. Apply up to four times daily.
• Emollient lotions or creams are lubricating skin products that help lock in moisture in skin that has been dried out by chlorine. You can use these between applications of medicated creams. Choose products that are hypoallergenic and fragrance-free.

If symptoms do not improve despite these OTC treatments, call your healthcare provider or see a skin specialist known as a dermatologist for further investigation.

Prevention

If you are prone to chlorine rash or have a skin condition (like psoriasis) that increases the risk of contact dermatitis, there are several things you can do before and after swimming to protect yourself.

Before swimming, rinse the skin to wash away excess sweat; this can help prevent the formation of chloramine. You can then apply a thin layer of petroleum jelly or pre-swim lotion 15 minutes before getting into the pool or hot tub. This creates a protective barrier that may prevent the loss of sebum.

Immediately after swimming, shower and wash with a gentle, non-drying soap. This helps remove chlorine from the skin. Follow up by applying an emollient-rich skin cream or lotion to lock in moisture.

It is also important to monitor chlorine levels in your pool or hot tub. If you have just added chlorine or used a "pool shock" product to treat algae buildup, wait at least several hours before getting into the pool. Avoid swimming until chlorine test strips indicate that the levels are safe.

Generally speaking, if the pool has a strong chlorine smell, chloramine levels are high. A "pool shock" treatment to help clear these irritating chemicals.

Summary

Chlorine rash is not an allergy but a form of irritant contact dermatitis caused by exposure to irritating chemicals. Symptoms include skin redness, swelling, rash, scaling, and itchiness.

Chlorine rash can usually be treated at home with over-the-counter hydrocortisone cream, Benadryl (diphenhydramine) cream, and emollient skin creams. To reduce the risk of chlorine rash, rinse off before swimming and apply a barrier cream or lotion. After swimming, rinse off again to remove excess chlorine and apply an emollient skin cream to lock in moisture.

A Word From Verywell

The only foolproof way to avoid chlorine rash is to stay out of the pool, which can be a big ask if you are an avid swimmer.

If you do not want to give up swimming in pools, you can convert your pool to saltwater or install an ultraviolet sanitizer that uses UV light to kill harmful microbes in pools.

If that's too costly an option, speak with your healthcare provider or a dermatologist about ways to manage irritant contact dermatitis both in and out of the water.

There are a few things you can do to try to keep a pool safe and limit chloramines. Rinse off in the shower prior to entering a pool to remove the oils and sweat from your skin. Keep feces and urine out of the pool. If you smell a chemical odor that indicates the presence of chloramines in the water or see feces floating in the water, immediately alert a pool operator, lifeguard, or clean the pool properly if it is your personal pool.