Hives are thick, red bumps also known as “welts” that can appear anywhere on the body. About 20 percent of Americans have hives at some time in their lives. It is often difficult to identify the cause of hives. A few of the things that can cause hives include medications, foods, environmental allergies, contact allergies, heat and cold.
Contact dermatitis is caused by physical contact with allergens in the environment. The rash is usually very itchy, red, and sensitive. The skin may even blister if the allergic response is robust. Plants such as poison ivy, poison sumac, or poison oak are common culprits in the development of this condition. In addition, your personal care products such as soap, detergents, and shampoos can sometimes cause contact dermatitis.