Allergy-related rashes are a broad term for a range of skin irritations due to chemical, food and environmental allergens. Symptoms and triggers of allergic rashes vary among individuals and in some cases between adults and children. The University of Maryland Medical Center notes that allergy rashes also may be linked such conditions as asthma, hay fever, drug side effects, food allergies and insect bite reactions. Additionally, some allergic rashes such as contact dermatitis occur on their own, without other allergy symptoms or illnesses. Consult your family physician for an accurate diagnosis and for the best way to prevent and treat rashes.Hives normally occur in association with other allergic disorders, such as food allergies, insect bites, animal allergies and hay fever. A study published by the American Academy of Family Physicians notes that contact dermatitis caused by a latex chemical allergy can also cause hives. this rash appears on the skin as red raised spots that feel inflamed and itchy. Hives typically occur on the face, chest, stomach, arms and hands and can occur in infants, children and adults.Eczema, or dermatitis, is an inflamed rash that causes redness, blisters, swelling, itching, dry skin, scaling and scabbing, and sometimes oozing or bleeding. Eczema can lead to hardening, thickening and scarring of the skin, and chronic symptoms can be debilitating in some individuals. this rash also causes mild to severe itching, and scratching can worsen the problem, particularly in infants and children. as outlined by Merck.com, eczema may be a skin reaction to food, drug, chemical or environmental allergens and is commonly associated with asthma and hay fever. In some individuals, eczema may be the only symptom of an allergy. Treatment for eczema depends on the cause of the rash.Contact dermatitis is a skin rash caused by direct contact with an allergen. this occurs when the body’s immune system reacts to a substance on the skin. In some cases, an individual develops an allergic reaction immediately after one exposure, while in other cases sensitivity occurs four to 24 hours after contact. this type of rash typically occurs in a small area and often has clearly visible boundaries in the shape of the contact irritation. for example, dermatitis from a metal allergy may occur in the shape of a ring, watch or bracelet that touches the skin. Other causes of this allergic rash include environmental, food and chemical allergens that come into contact with the skin anywhere on the body, such as liquid dishwashing detergent that irritates fingers and hands or laundry detergent that causes a rash when skin comes in direct contact with clothing washed in the detergent. Contact dermatitis occurs without other allergic symptoms and can cause severe itching, redness, inflammation, bumps and blisters on the skin.