There are two types of contact dermatitis: allergic contact dermatitis and irritant contact dermatitis.
Both types of contact dermatitis are itchy skin rashes that occur when the skin comes in contact with a chemical material that is either irritating or allergenic.
Allergic contact dermatitis occurs hours to days, after contact with the allergenic material, and can last up to several weeks even after the allergenic material is no longer in contact with the skin. The skin becomes itchy and red, and blisters can form.
Conversely, irritant contact dermatitis occurs anywhere from minutes to hours after contact with the irritating material. While the skin is usually red and itchy, blisters are rare.
Allergic contact dermatitis can be caused by many materials, depending on the person; common allergens are latex, leather, rubber, nickel, and topical medications containing neomycin and polymyxin B (such as Neosporin®). A dermatologist can use specialized skin testing known as patch testing to systematically expose the skin to different materials that are known to cause allergy to help identify if there is a particular material causing the allergy.
Irritant contact dermatitis can also be caused by many materials, such as water, soap, acids, alkalis, and solvents.
The primary treatment is to identify the material causing the irritation or allergy and to avoid further contact with it. The following medications are used to treat the symptoms:
- Topical steroids or anti-inflammatory medications, such as calcineurin inhibitors
- Oral steroids for when the reaction is severe