What Happens
The first time you eat a food
that triggers an
allergic reaction, your body's immune system
recognizes the food as a foreign substance (allergen). Your
body reacts by developing
antibodies against the food. When you eat the
offending food again, the antibodies attack the allergen, releasing histamine
and other chemicals that cause the symptoms of an allergic reaction.
Symptoms often develop within minutes, although they may not be apparent
for an hour or more. In some cases, symptoms may not develop for days. In
general, the sooner the reaction begins, the more severe it will be.
Symptoms may start with tingling and swelling of the mouth and tongue.
When the food allergen enters the stomach and intestines, cramping, nausea,
vomiting, and diarrhea can develop. Symptoms may occur throughout the body when
the food allergen is absorbed from the digestive system into the
bloodstream.
In moderate reactions, the body reacts with
hives
and itching, wheezing, nasal congestion, and
possibly dizziness or lightheadedness. Most of the symptoms of a moderate
allergic reaction subside in a few hours after
antihistamine medicine is taken or the food allergen
leaves the body. A skin rash (atopic dermatitis) may persist for
several weeks.
In severe reactions, the body releases larger
amounts of histamine and other chemicals that can cause life-threatening
anaphylaxis. This may happen in a few minutes to an hour. Symptoms of
anaphylaxis usually get better quickly after
epinephrine and antihistamines are given. Epinephrine,
which is given as a shot, stops the further release of the chemicals that cause
a severe reaction and counteracts the symptoms.