What are allergy shots?

Allergy shots are a form of beneficial treatment used when antihistamines, decongestants, topical steroids and other medications are not enough to control the symptoms of allergic rhinitis (“hay fever”), and some types of asthma as well as for stinging insect sensitivity. Gradually increasing doses of the substances to which you are allergic (as determined by history, skin tests, etc.) are administered in order to reduce your sensitivity to the offending agents. They should not be used in the treatment of food allergy.

How are they given?

Allergy shots are injections given just under the skin. . It is usually best to receive an injection in the middle third of your upper arm when you are standing with your arm relaxed by your side. You may find that it is more comfortable toward the front or side of the arm, rather than toward the back portion. Before starting a course of injections, you should be familiar with the intended schedule. Remember that it is only a guide, and that dosages may have to be altered by your doctor. There is an initial build-up period in which increasing amounts of the material you are allergic to is injected. A maintenance period of more spaced out injections follows for up to 5 years.

Are there any side effects and can they be prevented?

Reactions to injections may occur infrequently, and consist of minor local discomfort, or may be more serious. It is important to prevent the latter. Before receiving any injections you should verify that the name on the box, the serum bottles, and the schedule are indeed yours, and that the serum expiry date has not been passed. Since doses are usually built up slowly over a period of time, injections must be taken regularly. If you are overdue for an injection, it is wise to point out the delay to the administering physician or nurse so that dosage can be adjusted accordingly. You should be asked at each visit if you have had an adverse reaction after an injection,. If this is not asked, you should volunteer the information. If there was local swelling larger than the size of a quarter, dosage should not be raised, and should be repeated or lowered. Epinephrine should not be included in the injection, as this may mask a more serious reaction. Systemic reactions can take the form of sneezing, nasal congestion, dripping nose, itchy skin, hives, coughing, wheezing, disorientation, extreme lethargy, or even in rare cases, collapse and shock. These reactions may be life threatening and require immediate care. To prevent such reactions you will be asked to remain in the doctor’s office for about 30 minutes after an injection, and an injection should not be given if you are unwilling to wait. Since reactions to injections are more likely to occur if you are overtired, or are feeling unwell (especially if you have a fever), you should not take an injection under these circumstances. Exercise should not be undertaken for at least four hours after an injection. Resting quietly prevents excessively rapid absorption of the injected material. After a systemic reaction, it is usually not necessary to discontinue injections, but dosage must be reduced significantly.

What about pregnancy?

Therapy may be continued during pregnancy, but the dose is usually lowered. A course of injections should not be started nor dosages raised, however, during a pregnancy.

Downsview, Ontario

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ALLERGY HOTLINE (416) 633-2215
INFORMATION NOTES is for information purposes only. It is not meant to replace medical diagnosis or information. It is important to consult with your physician on any health matter.