What are allergy shots?
The allergy shot, also called allergy injection or subcutaneous immunotherapy (SCIT), is a form of treatment aimed at treating allergies. While allergy
medications can be very effective in improving allergy symptoms, they just cover up the symptoms. The allergy shot was devised as a way to treat allergies
by targeting the cause of allergies – the immune system (which is why allergy shots are also called “immunotherapy”).
Allergy shots are not new – they were first tried almost 100 years ago, in 1911 when 2 London doctors (Leonard Noon and John Freeman) used a watery
extract of boiled pollen to treat an allergic individual. Since then, allergy shots have been studied extensively and improved.
Allergy shots involve a series of injections given at regular intervals over a 3-5 year period. Initially, the shots contain minute amounts of allergens, but over
time the dose is gradually increased. As the treatment progresses, the body’s immune system becomes less sensitive to allergens, and symptoms gradually
Typically, each allergy shot prescriptions is made up of 4-5 vials. The treatment starts with a very weak concentration of allergens. Over a 3-6 months
period, the dose is gradually increased by using progressively higher doses from the more concentrated vials - this is called the buildup phase. During this
phase, shots are typically received once or twice a week. Once the full dose is reached (from the vial on the right, with the red colored liquid), the treatment
enters the maintenance phase. In the maintenance phase, patients typically receive shots every 2-4 weeks. It is recommended to continue shots for a total of
3-5 years in order to obtain the best long term benefits.
Is there a way to get to the full dose of allergy shots quicker?
Yes. As stated above, the typical build up for allergy shots takes 3-6 months and it can take 2-3 months before you begin to notice significant improvement
Another way to build up allergy shots is to "rush" it. With a "rush" build up, the equivalent of the first 10-15 doses are given in 4-8 hours, instead of 7-15
weeks. This means that you should reach the maintenance dose of allergy shots in nearly half the time it would normally take, and people often start to notice
an improvement in symptoms within about a month. This is a procedure that is not offered by most allergists, but which I do on a frequent basis at the
Greensburg office. Please contact our office if you would like more information on rush immunotherapy.
What are the benefits of allergy shots?
Allergy shots are effective in improving symptoms caused by pollens, molds, animals, dust mites, and cockroaches. Overall, allergy shots are successful in
up to 90% of patients with seasonal allergies and in 70%-80% of individuals with year long allergies. Symptoms do not improve overnight as it takes time to
build up the dose and for the immune system to change to a less allergic state. Symptoms gradually improve as the dose of the shots increases. Full results
are usually achieved within about 1 year of starting injections. Because allergy shots interact with the immune system, many people continue to have benefits
many years after they have completed their treatment.
- Allergy shots decrease the chance of new allergies. Studies demonstrated that the chance of developing new allergies to pollens and other
environmental allergens decrease by about 50%.
- Allergy shots reduce the risk of developing allergic asthma in individuals with environmental allergies by about 50-70%
- In allergic asthma, allergy shots result in a significant reduction in symptoms and medication use. In many, the asthma can completely go away. For
example, a study published in 1968, which looked at children with asthma, demonstrated that 70% of the children who received allergy shots for 4
years no longer had asthma. In the placebo group, only 20% of the kids became free of asthma during the study.
There are not many studies on eczema and allergy shots. The data available demonstrates that allergy shots might be effective in improving eczema—but
only if it is associated with environmental allergies, not food allergies.
Currently, allergy shots are not recommended for the treatment of hives, angioedema, food allergies, or eczema (if associated with food allergies).
Who can receive allergy shots?
Generally, children age 5 and above, and adults can receive allergy shots.
Allergy shots are a good treatment option if you have one of the following:
- Severe allergy symptoms which significantly affect quality of life, even while taking allergy medications
- Significant side affects from allergy medications
- Have a desire to avoid using medications for the long term
- Frequent ear or sinus infections which are felt to be from environmental allergies
- Allergic asthma
Allergy shots are generally not suitable for individuals with heart problems, taking beta-blocker drugs, or who have poorly controlled asthma. Individuals
considering allergy shots should discuss their particular case with a board certified allergist.
What are the side effects of allergy shots?
Generally, shots are very safe. Some reactions are possible since they contain particles that your body is allergic to.
The most common reaction is what is called a local reaction. A local reaction is an area of redness and swelling which occurs at the injection site. It may
happen almost immediately after an injection, or develop an hour or two later. A local reaction can be bothersome as it may be itchy, but it is not dangerous.
A local reaction goes away on its own within a few hours.
Much less frequently, individuals can develop allergic reactions with allergy shots. Studies show that overall, about 2% of individuals may experience an
allergic reaction. The majority of the time, these reactions are mild, with symptoms such as watery or itchy eyes, sneezing, itchy nose or ears, post nasal
drip, or hives. Very rarely, reactions can be very severe, with symptoms such as breathing difficulties, swelling in the throat, low blood pressure, or passing
out. Most allergic reactions develop within 30 minutes of an injection, therefore individuals are required to wait in the allergist's office for 30 minutes after
each injection. The allergist can then treat the reaction as needed if one were to develop.
updated 5 February 2013
Nelson HS. Allergen Immunotherapy: Where is it Now? J Allergy Clin Immunol 2007;119:769-77.
Allergen Immunotherapy practice in the United States: guidelines, measures, and outcomes. Ann Allergy Asthma Immunol. 2011;107:289-300.
Johnstone DE, Dutton A. The value of hyposensitization therapy for bronchial asthma in children - a 14-year study. Pediatrics 1968; 42:793-802.
Blazowski et al. Anaphylactic shock because of sublingual immunotherapy overdose during third year of maintenance dose Allergy 2008;63:374.
Cochard et al. Sublingual immunotherapy is not always safe alternative to subcutaneous immunotherapy. J Allergy Clin Immunol 2009;124:378-379.
Anthony Frew Sublingual immunotherapy NEJM 2008;358:2259-2264
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