Only a small number of things cause skin allergies
The number of potential skin allergens is endless: People react to soaps, laundry detergents, fabric softeners, shampoos, metals (nickel, cobalt, chromium, and zinc), adhesives, nail polish, topical medications, and plants, according to the American College of Allergy, Asthma and Immunology.
Most rashes are a sign of skin allergies
If your skin comes into contact with nickel in jewelry and you develop red, bumpy, scaly, itchy or swollen skin at the point of contact in a few days, that’s most likely a skin allergy. If, however, the reaction happens quickly, you may have irritant dermatitis—which isn’t an allergic reaction. “If someone has a skin reaction to something in a matter of hours it is not likely an allergic contact dermatitis, rather an irritant dermatitis,” says Adam Friedman, MD, associate professor of dermatology and director of the Supportive Oncodermatology Clinic at George Washington School of Medicine and Health Sciences in Washington, DC. The only exception is hives (officially, contact urticaria), which may occur immediately after contact at the site of contact. When in doubt, check in with your dermatologist or allergist for a definitive explanation. Make sure you know these medical conditions that may be mistaken for allergies.