Allergic contact dermatitis is a form of eczema that is caused by an allergic response to a substance that comes in contact with the skin. Irritant contact dermatitis is a form of eczema that occurs from a nonallergic inflammatory response to a substance that breaks down the skin barrier.

Allergic contact dermatitis (ACD) is a delayed hypersensitivity reaction. This allergic reaction normally occurs within 48-72 hours after the skin has been exposed to the offending substance. An example of ACD could be a rash that develops on the neck of someone who sprays perfume and has a fragrance allergy. 

Irritant contact dermatitis (ICD) is more common than allergic contact dermatitis and may involve repeated exposure to mild irritants or one exposure to a strong irritant that breaks down the skin. An example of ICD could be a dry, cracked rash on the hands of someone who uses bleach without proper protection from gloves.

Even very small quantities of an allergen can cause a skin reaction. What is surprising is that many people who develop contact dermatitis have been in contact with an allergen for years in their personal care or household cleaning products, but had not reacted to it in the past.

There are thousands of chemicals that can cause contact dermatitis. Some common allergens include:

• Nickel: A metal commonly found in jewelry, belt buckles, and some foods. It is one of the most common allergens in North America, affecting close to 20% of the population.
• Fragrances: The most common manmade and natural perfumes are found in cosmetics, hair care products, soaps, laundry detergents, fabric softeners, candles, air fresheners, dental products, and flavorings in foods.
• Preservatives: Chemicals such as formaldehyde, methylisothiazolinone, and parabens are common preservatives in cosmetics, soaps, lotions, and detergents.
• Propylene glycol: A preservative in numerous lotions, medicated creams, and prepared foods.
• Mercaptobenzothiazole: Used in making rubber products such as gloves, shoes, and goggles.
• Para-phenylenediamine: A chemical found in hair dyes and black henna tattoos.
• Topical antibiotic ointments: Ten percent of the US population is allergic to Bacitracin® and Neosporin®.
• Essential oils: Tea tree, lavender, ylang ylang, peppermint, and jasmine are the most common essential oils that cause contact dermatitis.

Anyone at any age can develop contact dermatitis, from infants to the elderly. Individuals with a history of eczema (atopic dermatitis) are more likely to develop contact dermatitis due to their broken skin barrier that allows allergens to interact with the immune system in their skin.

Contact dermatitis is also much more common among those in certain occupations such as health care workers, metal and construction workers, cleaners, hair stylists, and nail technicians.

Contact dermatitis is a red, scaly, itchy rash that is often unpredictable. Skin that has been exposed to the offending substance often swells, becomes inflamed and tender, and sometimes blisters. It can occur anywhere on the body, but common sites include the eyelids, face, neck, hands, fingers, trunk, and feet.

These symptoms may persist for 6-8 weeks if the rash is untreated and can continually recur with repeated exposure to the allergen.

If you are concerned that you are experiencing contact dermatitis, discuss your symptoms with your dermatology provider. Some contact allergies are easy to recognize, such as a rash that develops from ear piercings caused by a nickel allergy. The majority of allergies are difficult to identify, as the skin reaction develops several days after exposure to the chemical.

Allergy patch testing is performed to determine what substances may be causing contact dermatitis. It is a painless, needle-free process that takes place over two visits. The patch test can be customized based on your medical history, occupation, environment, and skin care products you may use.

Patch testing involves applying small amounts of common allergens onto an adhesive patch, which is then applied to the skin, typically on the back. The patch is removed 48 hours later and the skin is read 96 hours after patch application to see if a reaction to any of the allergens has occurred.

For any irritants or allergens that are identified, counseling will be provided on how to avoid the allergen and manage the symptoms of contact dermatitis.

As members of the American Contact Dermatitis Society, we provide all of our patients with customized lists of safe products that make it easier to find personal care products that are free of the allergens that affect you.

The best course of treatment is to find the cause of the contact dermatitis and avoid it. This could potentially cure your rash. 

Your dermatology provider may prescribe topical medications to calm inflammation and help repair your skin. In severe cases, oral medications are prescribed for widespread dermatitis. Choosing mild soaps and lotions that are free of fragrance can help to calm irritated skin.

Unfortunately, if you have developed ACD, you will likely have it your whole life. Exposure to even a small amount of allergen can cause a recurrent skin reaction. The good news is that with proper identification of your allergens through patch testing and helpful education and safe product resources, we can help you live an allergen-free life.