Allergies are an abnormal response of the immune system. People who have
allergies have an immune system that reacts to a usually harmless substance in
the environment. This substance (pollen, mold, animal dander, etc.) is called an allergen.
Allergies are a very common problem, affecting at least 2 out of every 10 Americans.
If the allergen is in the air, the allergic reaction will likely occur in the eyes, nose and
lungs. If the allergen is ingested, the allergic reaction often occurs in the mouth, stomach,
and intestines. Sometimes enough chemicals are released from the mast cells to cause
a reaction throughout the body, such as hives, decreased blood pressure, shock, or
loss of consciousness.
Most allergies are inherited
They are passed on to children by their parents. People inherit a tendency to be allergic,
although not to any specific allergen. When one parent is allergic, their child has a 50%
chance of having allergies. That risk jumps to 75% if both parents have allergies.
