Allergy Shots: How They Work

11 de abril de 2024

3 min de lectura

Allergy shots are injected treatments used over a period of time (usually 3 to 5 years) to treat severe allergies.

What are allergy shots?

Also known as allergy immunotherapy or subcutaneous immunotherapy, allergy shots are used as a long-term treatment for severe allergy symptoms. Each shot contains a tiny amount of allergens that stimulate the immune system but not enough to cause a full-blown allergic reaction.

The amount of allergen in the allergy shots is increased over time to help your body develop decreased sensitivity to them. This increases the immune system's ability to tolerate the allergens, causing the allergy symptoms to diminish.

Allergy shots may be used to treat people with:

Allergic conjunctivitis or eye allergies
Allergic rhinitis
Allergic asthma
Allergy to insects like bees or other stinging insects

Allergy shots can benefit people who suffer from severe allergy symptoms year-round and do not want to take medications for a long time.

Allergy shots are not given to people who:

Have a fever of 100℉(37.7 ℃) or higher
Have severe asthma
Have a heart condition
Are pregnant
Take ACE inhibitors or beta blockers

You cannot treat food allergies with allergy shots.

How do allergy shots work?

You can get allergy symptoms when your immune system tries to attack allergens. Allergens are the substances that trigger an allergy attack. Some examples of allergens include:

Dust mites
Pollen
Insect venom
Mold spores
Animal dander

Allergy shots work like vaccines. They contain a tiny amount of allergen that triggers the immune system to build up tolerance over time.

Allergy shots work in two phases.

Build-up phase

This involves receiving injections with an increased dose of allergens about one or two times a week. Depending on how often the injections are received, the phase lasts for 3 to 6 months.

Maintenance phase

The maintenance phase depends on your response to the buildup phase and your sensitivity to the allergens. You will receive the doses after every 3 to 4 weeks for 3 to 5 years or longer.

Side effects of allergy shots

Side effects from allergy shots appear locally as skin reactions like itching, redness, and swelling. Some people develop a runny nose or mild nasal stuffiness.

Although rare, such reactions can develop in the entire body, the condition called systemic reaction.

Systemic reactions include:

Hives
Tightening of chest
Wheezing
Lightheadedness
Flushing
Itchy or tightness in throat
Itchy red eyes and ears
Rarely, severe life-threatening allergic reactions like anaphylaxis can cause dizziness and breathing difficulties

Taking antihistamines or other medications may prevent reactions at the injection site but does not prevent anaphylaxis.

Are allergy shots effective?

Allergy shots can offer long-term relief from allergic reactions long after the treatment stops. Most people see results after one year of taking maintenance shots, while others notice benefits much earlier in the maintenance phase.

Allergy shots may not work in the following cases.

Where treatment is stopped because of reactions.
Where there is continued exposure to very high levels of allergens.
When allergens are missed during the initial evaluation.
When there are not enough allergens in the allergy shots.

When to call the healthcare provider?

Contact your healthcare provider if:

Your allergy symptoms get worse after several months of treatment.
You have reactions or symptoms after injections.
You need to reschedule your appointment.
You have any questions or concerns.

Sources

Información general, no consejo médico

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