Food allergies occur when the body’s immune system mistakenly believes that a food protein, or allergen, poses a threat. In response to the perceived threat, chemicals are released into the blood. These chemicals in turn cause the symptoms of an allergic reaction.
Affected Body Systems
Allergic reactions to food can affect four body systems: the skin, gastrointestinal system, respiratory system and cardiovascular system. Reactions affecting the skin are the most common and can manifest in a number of ways, including a mild rash, hives, eczema and swollen skin (or angioedema).
Hives are the most-common allergic response to food. They are sometimes called urticaria or a nettles rash and are red, very itchy, swollen areas of skin. Hives have a central, raised white bump surrounded by an area of redness. Some people believe hives look like a cluster of mosquito bites. Sometimes new clusters will appear just as other areas are clearing up. Hives can occur alone or with other symptoms. Some people get hives just by touching the food to which they are allergic.
Eczema, or atopic dermatitis, is a skin condition that is itchy, scaly and red. Located on the face, scalp, arms and legs, eczema is a chronic condition that is aggravated by food allergies. Unlike hives, it does not vanish, but lingers long after ingestion. Furthermore, eczema can be a warning sign in very young children that a food allergy may exist. In fact, 37 percent of children with moderate eczema also have a food allergy.
When the deep layers of skin swell in response to a food allergen, this is called angioedema. According to the World Allergy Organization, angioedema is caused by a buildup of fluid leaking from thin-walled blood vessels. It can accompany hives or occur alone.
Other Skin Reactions
There are several other types of skin reactions to food allergens. These reactions typically occur in children. For instance, infants and toddlers often develop a red rash around their mouths when they eat something to which they are allergic. They also may have “allergic shiners,” which are dark blue, black or reddish circles under their eyes. Typically, children with a milk allergy will have allergic shiners. They also may have reddish earlobes and a reddened nose. The red nose is often referred to as an “allergic salute.” In other words, when children rub their noses red because they itch, it looks like they are saluting.
Food allergies can worsen over time with each reaction becoming more severe. Skin reactions are often the first sign that something is wrong. Ultimately, if the offending food is not eliminated from the diet, severe allergic reactions may begin to involve more than just the skin. Some reactions can even become life threatening. If you are experiencing skin reactions when you eat particular foods, it is best to visit an allergist to determine what is causing your body’s response. An allergist can determine the best treatment for your condition.