Find out more about how allergy shots work.
Allergy Shot Basics: The Nuts and BoltsThe method of immunotherapy consists of starting at a small dose that will not cause an allergic reaction, with slowly advancing the dosage until the person becomes tolerant to large amounts of the extract. These injections are initially given once to twice a week until a maintenance, or constant dose, is achieved. This usually takes approximately 3 to 6 months. Once the maintenance dosage is reached, the allergic symptoms are largely resolved in most patients. Thereafter, the injections are given every two to four weeks. Therapy is continued for 3 to 5 years total, after which the patient continues to get benefit for another 5 to 10 years or longer, even after the shots are stopped. If the shots are stopped prior to a total of 3 years, the allergic symptoms typically return more quickly.
Potential Side Effects of Allergy ShotsThe risks of immunotherapy consist of the possibility of experiencing an allergic reaction to the allergy shot. Most allergic reactions consist only of mild to moderate swelling and itching at the site of the injection. These reactions occur frequently, but rarely require any change in treatment. A large swelling may require an adjustment of the immunotherapy dosage or a change in the frequency and amount of the shots. Less commonly patients experience whole-body allergic reactions, sometimes called anaphylaxis. Most of these reactions are mild and consist of itching of the skin, nasal allergy symptoms and worsening asthma. Others are more severe and can present as cough, chest tightness, wheezing, throat tightness, shock and rarely can be life threatening. For this reason, it is required that patients remain in the physician’s office for 30 minutes after the injection, since most serious reactions occur during this time. These reactions are typically easily reversed with medicines such as injectable epinephrine and antihistamines. allergic reactions in a large percentage of people, so various medications (such as antihistamines and corticosteroids) are often given in order to prevent or minimize these reactions. A person undergoing rush immunotherapy should be prepared to spend at least a couple of days in the allergist’s office, receiving many allergy shots over this time.
Some children are mature enough to understand the process of allergy shots at age 5 or 6, while other children may not be mature enough until 8 or 9 years of age. Still other children won’t be mature enough until 11 or 12. A good test is to see how the child did with allergy skin testing – if the child did not fight or cry with this procedure, there is a good chance that they are ready for allergy shots.
Read more: Do allergy shots hurt?
In addition to certain medical problems, older patients are more likely to be taking medications that place them at a higher risk of reactions from allergy shots. Beta-blockers are a class of medication used to treat high blood pressure, hearts, and are frequently taken in someone who has had a heart attack. These medications can worsen anaphylaxis and make reactions to allergy shots more difficult to treat, and therefore allergy shots should not be given to someone who requires a beta-blocker medication.
You’ve learned all about allergy shots, now learn more about allergy drops (sublingual immunotherapy).
Cox L, Nelson H, Lockey R. Allergen Immunotherapy: A Practice Parameter Third Update. J Allergy Clin Immunol. 2011 Jan;127(1 Suppl):S1-55.
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