Contact dermatitis is a red, itchy rash caused by direct contact with a substance or an allergic reaction. It can be caused by an irritation or an allergic process. If an irritant contact dermatitis, the rash typically develops within hours of exposure and can last 2-4 weeks. An allergic contact dermatitis or hypersensitivity (ie. poison ivy, nickel, or other allergic mediated process) may take 24-72 hours to develop after contact and last for several weeks if not treated and contact is not removed.
Signs and symptoms of contact dermatitis include:
A red rash
Itching, which may be severe
Dry, cracked, scaly skin
Bumps and blisters, sometimes with oozing and crusting
Swelling, burning or tenderness
There are two types of contact dermatitis – irritant and allergic.
Irritant contact dermatitis is the most common – this nonallergic skin reaction occurs when a substance damages your skin’s epidermis. The reaction may emerge after a single exposure, or from repeated exposure to even mild irritants. Common irritants include solvents, rubbing alcohol, bleach and detergents, shampoos, airborne substances like sawdust, plants, fertilizers and pesticides.
Allergic contact dermatitis occurs when a substance triggers an immune reaction in the skin. It usually affects only the area that came into contact with the allergen, however it can also present after something that enters your body through food, medicine or dental procedures. Common allergens include:
Nickel (ex. jewelry)
Medications (antibiotics and oral antihistamines)
Formaldehyde (in preservatives, disinfectants and clothing)
Personal care products like deodorants, body washes, hair dyes, cosmetics and nail polish
Fragrance – Balsam of Peru – which is used in many perfumes, cosmetics, and flavorings
Plants or Foods – such as poison ivy from the urushiol resin and mango
Airborne substances such as ragweed pollen or insecticides
Photoallergic contact dermatitis – products that cause a reaction after sun exposure, such as some sunscreens and oral medications
Treatment can usually be managed at home with methods that will soothe inflammation and reduce itch.
Topical anti-itch creams or topical steroids
Oral anti-itch medications such as diphenhydramine (Benadryl) or other antihistamines
Application of cool, wet compresses
Oatmeal baths – sprinkle oatmeal-based bath product into a cool bath
Avoid scratching which can lead to infection
In more severe cases your doctor may prescribe an oral or topical steroid or inject a systemic steroid to reduce inflammation and itch. If secondary infection develops, an antibiotic may be prescribed. If itch is severe, an oral antihistamine may be prescribed.
Eliminating exposure to irritants is the best method of prevention. Your doctor may be able to help you pinpoint the culprit, and in some cases may recommend a patch test to identify a potential allergen. During a patch test, a small amount of potential allergens are applied with adhesive patches that are placed on your skin. The patches remain on your skin for 2-3 days, and are then examined for skin reactions.