Many kids have allergies — in fact, they're the most common cause of chronic nasal congestion in children.

Allergen immunotherapy (allergy shots) can be an effective treatment for allergies. Here are the basics on allergy shots and how to help a child deal with them.

Why Allergy Shots Are Used

An allergy occurs when the body's immune system has an exaggerated reaction to a usually harmless substance. The most common allergens (substances that trigger the allergy) are dust mites, molds, pollen, pets with fur or feathers, stinging insects, and some kinds of foods.

The body reacts to the trigger by releasing chemicals, one of which is histamine. Allergic symptoms can include runny nose, congestion, sneezing, itchy eyes, and ear itching or popping. Asthma also might occur in some kids.

The best way to prevent or control allergy symptoms is to avoid triggers. An allergist (a doctor trained to identify and treat allergies) will look for causes of an allergy by testing a person's reaction to specific allergens with skin or blood tests. Then, based on the test results, the allergist or another doctor can recommend treatments, including medications and ways to avoid exposure to allergens.

If environmental control measures and treatment with basic allergy medications are not successful, allergy shots might be recommended as the next step.

How Allergy Shots Help

Allergy shots help the body build immunity to specific allergens, thus eventually preventing or lessening reactions from exposure to the allergen. Allergy shots also decrease the risk of developing asthma by 50% and reduce the chance of developing new allergens.

The shots contain a purified form of the allergens that are causing problems. The course of shots is usually given over a 5-year period. The dosage of the allergen is gradually increased over the first 4 to 5 months to a monthly maintenance dose, which is usually given for up to 3 years. After 5 years of getting allergy shots, a patient may no longer seem to be allergic.

If your doctor recommends allergen immunology, your child might begin receiving shots containing very small doses of allergen once or twice a week. The dose is slowly increased with each shot to allow the immune system to safely adjust and build immunity to the allergens. This is called the buildup phase.

Your child might not get symptom relief from allergies until higher doses are achieved at the end of the buildup phase. Once the highest effective and safe dose is reached, the frequency of shots gradually decreases to weekly, then biweekly, and then possibly monthly. This is called maintenance.

Are Allergy Shots Safe?

Allergy shots are really like vaccinations: They boost the defenses of the immune system to help the body reduce the allergic reaction. Given by a well-trained and experienced health professional, allergy shots are safe and effective and can be given to children as young as 4 or 5 years old.

Allergy shots, which are given year-round, work better against some substances than others. Generally, the shots are most effective against insect venoms and allergens that are inhaled, such as pollens, dust, molds, and animal dander.

When your child receives allergy shots, he or she may experience a reaction near the site of the injection. A patch of skin on the arm approximately the size of a quarter may itch and swell. This reaction is a signal that the body is responding to the allergen. You can treat this reaction by applying ice to the area and giving your child an antihistamine.

More serious reactions, such as hives and itching all over the body or wheezing and breathing difficulties, are unusual and occur in less than 2% of patients.

Shots might seem like an unusual way to treat allergies, but they're effective at decreasing sensitivity to triggers. The substances in the shots are chosen according to the allergens identified from a person's medical history and by the allergist during the initial testing. The U.S. Food and Drug Administration (FDA) oversees the standards used in preparing the materials for allergy shots given in the United States.

The American College of Allergy, Asthma & Immunology offers these tips to parents to make sure their kids receive allergy shots safely:

• Allergy shots should be administered only under the supervision of an allergist/immunologist or other doctor specifically trained in immunotherapy.
• A child who is ill, especially with asthma or respiratory difficulties, should not receive further allergy shots until a doctor says it's safe.
• To avoid adverse interactions, tell the doctor administering the injections beforehand of any current medications your child is taking.

Allergen immunotherapy isn't necessary for everyone with allergies. Many kids get along fine by living in homes that are as free as possible of allergens or by taking allergy medication during peak allergy season.

But many kids battle allergies year-round, and some can't control their symptoms with medications. For them, allergen immunotherapy can be beneficial.

Side Effects and Reactions

Allergy shots are extremely safe when given properly, but they do have the potential for rare but serious reactions. This is because treatment involves exposure to the substances to which someone is known to be allergic. A qualified allergist/immunologist will have all the medications and equipment necessary at the office to treat a serious reaction immediately.

Every time your child receives an injection, your doctor will have him or her wait 30 minutes in the office to make sure there is no adverse reaction. The doctor's staff will be watching for early signs and symptoms that could require emergency procedures and medications. If a severe reaction occurs, 98% of the time it will occur within 30 minutes of the shot and the reaction will usually respond to treatment with an injection of epinephrine (adrenaline).

In the event of a severe reaction, the doctor will probably reduce the dosage of allergen in the next injection to allow your child's system to build immunity more gradually.

Millions of people each year receive allergy shots without problems; however, to ensure safety, doctors recommend that immunotherapy be given in a controlled environment where the physicians and other health care personnel are trained to respond to an emergency. Board-certified allergists/immunologists have had a minimum of 5 years of training after medical school, which ensures that patients who have problems are cared for according to the highest standards.

In some cases, for convenience, the allergist/immunologist might work together with a child's primary care doctor so that some or most of the shots can be given by the doctor at his or her office.

Finding an Allergist/Immunologist

A primary care doctor can usually recommend a qualified allergist/immunologist. Or ask a family member or friend who is seeing an allergist/immunologist for a recommendation.

And the website of the American Academy of Allergy, Asthma Immunology, www.aaaai.org, has a listing of allergists by location.

Helping Your Child Cope

An allergy shot is given with a needle that is smaller than those used for most childhood vaccinations, which makes it less painful. Still, for some kids any shot can seem scary. A parent's positive and supportive attitude can go a long way toward helping a child accept the treatment and achieve successful results. Treatment seems to go much better if the parent is confident and committed to the child getting the immunotherapy.

Allergy shots can seem a bit scary at first. But understanding their benefits and how they work will help you and your child accept them as routine.

Reviewed by: William J. Geimeier, MD
Date reviewed: July 2009