Allergies. Irritation and allergic reactions can also cause itchy skin. Allergic contact dermatitis occurs when the skin comes into direct contact with an allergen. The result of the skin allergy is a red, itchy rash that can include small blisters or bumps..
More information about Allergies Itchy Skin
Skin allergies can also cause hives and swelling deep in your skin, called angioedema. If you can’t avoid contact with an allergy trigger, you can usually treat the rash and ease the itching. And you can’t pass it to anyone else..Allergic contact dermatitis occurs when your skin comes in direct contact with an allergen. For instance, if you have a nickel allergy and your skin comes in contact with jewelry made with even a very small amount of nickel, you may develop red, bumpy, scaly, itchy or swollen skin at the point of contact..