Food Allergies
What is it?
A food allergy
occurs when a person has an allergic reaction to a certain
food that he or she has eaten. Food allergies are not the
same as food intolerances, which are undesirable physical
reactions to certain foods.
Who gets it?
Food allergies
are more common in children, and are more likely to occur
in children with other allergic conditions, such as severe
hay fever, eczema, or asthma. Because food allergies can
be inherited, children with family members who have food
allergies are more likely to have them also.
What causes
it?
An allergic
reaction occurs when the immune system produces antibodies
and other disease fighting cells in response to an
allergen, in this case a specific food. The antibodies
release chemicals that actually injure the surrounding
cells and cause the physical symptoms of an allergic
reaction. Certain antibodies release histamines, which
affect the skin, mucous membrane, mucous gland, and smooth
muscle cells. Life-threatening allergic reactions can
occur without any previous symptoms of allergy. Although
allergies can be triggered by just about any food, peanuts
are the most common cause of allergies. Milk products and
eggs usually cause infant food allergies. Other common
sources of food allergies include soybeans, wheat, fish,
shellfish, and other nuts that grow on trees.
What are the
symptoms?
A child with a
food allergy will have allergic symptoms within two hours
of eating a food that is an allergen to him or her. Common
symptoms include diarrhea or vomiting; swelling of the
lips, tongue, or inside of the mouth, which can cause
difficulty with breathing; itching; skin rash; and hives.
The child may also have some nasal congestion, sneezing,
and runny nose. However, people with severe food allergies
can experience a dangerous condition called anaphylaxis.
Symptoms include sudden anxiety and weakness, sudden
headache, difficulty breathing, tightness in the chest,
very low blood pressure, loss of consciousness, and shock.
Anaphylactic shock can occur within minutes and result in
death. A patient in anaphylactic shock needs immediate
medical treatment. Food allergies can also trigger
migraine headaches, asthma attacks, and abdominal pain.
How is it
diagnosed?
Unless your
child has had an anaphylactic reaction to a certain food
and the source of the allergy is obvious, your doctor will
ask you to keep a diary of the foods your child eats and
the symptoms he or she experiences. Then, you will stop
the food that appears to be causing the reaction. After a
short period of time, your doctor will have you
reintroduce that food to your child’s diet to see if the
same symptoms occur. Please note that any food that causes
an anaphylactic reaction should not be given to the child.
Your doctor may also order a skin prick test. The doctor
will prick the skin, usually on the back or the arm, with
a small needle that has been soaked in a food extract.
After about 15 minutes, the doctor will check for a
reaction, such as a small red bump, in the area that was
pricked. Blood tests can also detect food allergies by
measuring the amount of certain antibodies in the blood.
The doctor may also perform a food challenge test, in
which small amounts of the suspect food are hidden in a
substance such as applesauce. After the child eats the
food, he or she is carefully watched for any type of
reaction. The doctor may gradually increase the amount of
the food during this test.
What is the
treatment?
The first
course of treatment for food allergies is for the child to
stop eating the food that causes the allergy symptoms. If
your child has an allergic reaction that includes itching
and hives, your doctor can recommend an antihistamine that
will relieve these symptoms. If your child is allergic to
many foods in a single food group, your doctor will
recommend supplements to replace the vitamins or minerals
that the child’s diet is missing. Breastfeeding mothers
should avoid eating foods to which their infant is
allergic. Anaphylactic shock is treated with an injection
of epinephrine, a hormone that stimulates the heart and
relaxes the airways. This may be combined with an
injection of an antihistamine, which counteracts the
histamine produced by the immune cells during an allergic
reaction. Carry a self-injection kit for emergency
treatment if your child is known to have severe food
allergies. However, you should still seek medical care
after any type of reaction to a food. Many children
eventually outgrow food allergies. Your doctor can guide
you in how and when to reintroduce foods to determine if
this is a possibility. However, most people never outgrow
allergies to certain nuts, fish, and shellfish.
Self-care tips
If your child
has food allergies, take care to ensure that he or she
does not eat those foods, and that the child’s school is
aware of the allergies. Avoid giving any child fish,
peanuts, or peanut products until after the age of two. A
child with severe food allergies wear a Medic-Alert
bracelet that identifies his or her condition.
This information has been designed as a comprehensive and quick reference
guide written by our health care reviewers. The health information written
by our authors is intended to be a supplement to the care provided by your
physician. It is not intended nor implied to be a substitute for
professional medical advice.
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