Food
allergies are very common. Up to 5% of children and 2% of
adults in the United States are estimated to have food allergies.
With a true food allergy, an individual's immune system will
overreact to an ordinarily harmless food. The most common
food allergens are milk, eggs, peanuts, wheat, soy, tree nuts,
fish, and shellfish. Reactions to these foods may be serious
or even fatal. Even more people have food intolerances, defined
by an abnormal response to a food that is not an allergic,
or immune, reaction.
Symptoms
of allergic reactions to foods The most common allergic skin
reaction to a food is hives. Hives are red, itchy, swollen
areas of skin that may arise suddenly and leave quickly. Hives
may occur alone or with other symptoms, such as swelling of
the lips or tongue. Atopic dermatitis, or eczema, is another
condition which can be triggered by foods. It is characterized
by dry, scaly patches of skin on the arms, legs, trunk, or
face. Asthma symptoms such as coughing or wheezing may be
triggered by foods, especially in infants. Gastrointestinal
symptoms of food allergy include vomiting and diarrhea, itching
and swelling of the mouth and throat, and abdominal pain.
In
infants, non-allergic reactions to certain foods, especially
fruits, are common. For example, a rash around the mouth due
to acids in foods like tomatoes, strawberries, and oranges
occurs frequently. However, other reactions are allergic and
may cause more severe symptoms when the food is eaten again.
This is especially the case with reactions caused by milk,
egg, and peanut.
In
some cases, consuming a food to which one is allergic can
cause a life-threatening reaction called anaphylaxis. The
first signs of anaphylaxis may be flushing, tingling in the
mouth, or hives. Other symptoms may include light-headedness,
difficulty breathing, swelling, vomiting, diarrhea, or even
low blood pressure. Symptoms of anaphylaxis are reversed by
treatment with epinephrine (adrenaline). Antihistamines and
other emergency measures may also be helpful. It is essential
that anyone with symptoms of anaphylaxis get emergency treatment
immediately.
As
they grow older, some children may tolerate foods that previously
caused allergic reactions. Most children with milk and egg
allergy will outgrow it, as will 20% of patients with peanut
allergy. Patients should have periodic food allergy check-ups
with an allergist to see if this has occurred. Other allergic
conditions, such as atopic dermatitis, allergic rhinitis (hayfever),
and asthma are also more likely to develop if someone has
food allergies.
