Allergies occur when the immune system of a sensitive person overreacts to an irritating substance, or allergen. Itchiness, rashes and swelling usually occur when the skin is affected. The symptoms usually appear on the parts of the body that directly contacted the allergen, like the face and hands, but the puffiness and itchiness can spread if the allergy becomes severe.
Swelling and Hives
People with food or drug allergies may experience hives and angioedema on exposure to allergy-causing substances. Hives are tiny, red bumps that appear on the surface of the skin, whereas angioedema is swelling of the deeper skin layers. A person with a food allergy may initially experience itchiness or swelling around the mouth upon eating the allergy-causing food. The mouth, throat, face and the entire body may swell or get puffy if the allergy worsens.
An allergic rash called eczema occurs in some people who have chronic skin allergies or a family history of allergies. The rash is very itchy and either dry and scaly or weepy and infected. Certain foods, emotional stress, cat dander, house dust, sweating, soaps or wool can trigger a flare-up of eczema. In infants, the itchy rash appears around the cheeks, forehead and scalp. Older people may develop rash on the face, neck, elbows and knees. People who suffer from chronic eczema may experience intense, uncontrolled itchiness on random parts of the body.
Contact dermatitis appears as an itchy, blistery rash where there was direct contact with irritating substances such as nickel, perfumes, rubber or latex, hair products and cosmetics. The most commonly affected body parts are the face and hands. Contact allergy worsens when the skin is re-exposed to the irritant, and even a very small amount of the allergen can cause severe allergies.
Allergic rashes, swelling and hives can become very itchy, but scratching will only worsen the symptoms. Avoid rubbing or touching the affected areas. Instead, take an over-the-counter antihistamine and apply a topical hydrocortisone cream to relieve the itchiness and bring down the swelling. Swelling that occurs in the mouth, tongue and throat may make breathing difficult and become life threatening. If available, give a shot of autoinjector epinephrine and call 911 immediately to prevent symptoms from worsening.