Food allergy is an abnormal response to a food triggered by your body's immune system. Allergic reactions to food can sometimes cause serious illness and death. Tree nuts and peanuts are the leading causes of deadly allergic reactions called anaphylaxis.

For someone with a food allergy, eating or swallowing even a tiny amount of a particular food can cause symptoms such as skin rash, nausea, vomiting, cramping, and diarrhea. Because the body is reacting to something that is otherwise harmless, this type of allergic reaction is often called a hypersensitivity reaction.

Do infants and children have problems with food allergy?
The Answer is Yes: Allergies to milk or soy formula (a milk- substitute made from soybeans) can occur in infants and young children. These early allergies sometimes do not involve the usual hives or asthma, but rather can cause infantile colic, and perhaps blood in the stool or poor growth.

Causes
In adults, the foods that most often trigger allergic reactions include:

• Fish and shellfish, such as shrimp, lobster and crab
• Peanuts
• Tree nuts, such as walnuts
• Eggs

Problem foods for children are eggs, milk (especially in infants and young children) and peanuts.

Symptoms

A person with a food allergy can have symptoms beginning as soon as 2 minutes after eating the food, but reactions may take 1-2 hours to appear. Occasionally, symptoms abate quickly, only to recur in 3-4 hours.

The most common symptoms include the following:
• Itching of the skin followed by hives, a rash of raised, reddish bumps or wheals
• Swelling of the lips and mouth
• Belly cramps
• Nausea
• Vomiting
• Diarrhea

Other symptoms may include the following:
• Itching and watering in the eyes
• Runny or stuffy nose

Symptoms of a more severe reaction could include the following:
• Shortness of breath or difficulty breathing
• Tightness in the chest
• Feeling of tightness or choking in the throat
• Rapid or irregular heart beat
• Feeling dizzy or light-headed
• Losing consciousness

Treatment

Food allergy is treated primarily by dietary avoidance. Avoiding the offending allergen in the diet is the primary treatment of food allergy. Once a food to which the patient is sensitive has been identified, the food must be removed from the diet.