Allergy shots, also known as allergen immunotherapy, are a form of long-term treatment that decreases symptoms for allergic rhinitis, allergic asthma, stinging insect allergies and some food allergies. Allergy shots work by gradually exposing the immune system to small amounts of the allergens causing symptoms. Over time, the body builds up tolerance to the allergens, reducing immune system overreaction and allergy symptoms.
How Allergy Shots Work
Allergy shots contain extracts of the specific allergens that trigger an individual’s allergic reactions. The extracts are injected under the skin, with doses gradually increased over time. This controlled exposure trains the immune system to tolerate the allergens, rather than overreacting to them.
Initially, allergy shot doses contain very small amounts of the allergen extracts. The doses are gradually increased on a set schedule under medical supervision, which allows the immune system to adjust without experiencing major allergic reactions. After reaching a maintenance dose, the shots continue to be administered monthly for 3-5 years. This ongoing exposure maintains the immune system’s tolerance to the allergens.
Benefits of Allergy Shots
Allergy shots can provide long-lasting allergy relief after the treatment is discontinued. Benefits may include:
- Decreased allergy symptoms like sneezing, itching and runny nose
- Reduced need for allergy medications
- Prevention of new allergen sensitivities
- Decreased asthma symptoms and less need for inhalers
Studies show allergy shots can be effective for at least 5 years after ending treatment. Some people experience lasting relief for many more years or even permanently. Allergy shots also have the advantage of treating the underlying allergies rather than just temporarily masking symptoms like antihistamines.
Types of Allergy Shots
There are a variety of allergy shot formulations containing different allergens or combinations of allergens:
| Allergen Extract | Allergy Shot Brand Names |
|---|---|
| Grass pollen | Grastek, Oralair, Ragwitek |
| Ragweed pollen | Ragwitek |
| Dust mites | Odactra |
| Cat dander | Fel d 1 |
| Multiple allergens | Alutard SQ, Aquagen SQ |
The specific allergy shot prescribed will depend on the allergens identified from allergy testing. Shots containing single allergen extracts are used when a person is sensitive to just one or two allergens. Multi-allergen treatments can be used for people with numerous allergy triggers.
Considerations
There are some important considerations when determining if allergy shots are the right treatment option:
- Time commitment – Allergy shots involve regular injections over 3-5 years.
- Cost – The cumulative cost over years of treatment can be high depending on insurance coverage.
- Potential reactions – Local reactions like swelling at the injection site are common. Systemic reactions like hives, asthma flares or anaphylaxis rarely occur.
- Age limitations – Allergy shots are approved for children ages 5 and older.
- Pregnancy – Allergy shots are not given to pregnant women since the effects on a fetus are unknown.
Talk to an allergist to find out if allergy immunotherapy is appropriate for your situation.
The Allergy Shot Schedule
Allergy shots involve an initial build-up phase, a maintenance phase, and sometimes a taper phase. The process gradually exposes the immune system to increasing amounts of allergens.
Build-up Phase
The build-up phase typically spans 4-6 months. During this time, weekly injections slowly increase the allergen extract dose from a very low starting amount to the target maintenance dose:
- First injection contains only a tiny portion of the maintenance dose.
- Dose is increased incrementally with each shot, usually doubled or tripled.
- Dose increases continue weekly until maintenance dose is reached.
- Build-up proceeds more slowly if reactions occur.
Patients wait 30 minutes after each shot to monitor for adverse reactions during build-up. The gradual increments allow the immune system to adjust without overwhelming it.
Maintenance Phase
The maintenance phase involves receiving a regular injection of the peak dose. This phase typically lasts for 3-5 years to maintain the immune system’s tolerance to allergens. Maintenance shots are usually given every 2-4 weeks.
Taper Phase
After completing the recommended maintenance period, allergy shots often taper off instead of stopping abruptly. The taper phase reduces the dose incrementally over several months before ending treatment. This allows the immune system to adjust and maintain its tolerant state.
The Allergy Shot Process
If you are considering allergy shots, be prepared for the extensive process involved:
- Allergy testing – Blood and/or skin testing identifies your unique allergens.
- First appointment – Discussion of benefits, risks and expectations of immunotherapy.
- Consent forms – You must sign consent indicating understanding of possible reactions.
- Shot scheduling – Weekly build-up shots precede monthly maintenance shots for years.
- Wait after shots – You’ll be monitored for 30+ minutes after each shot for potential reactions.
- Symptom reporting – You must report local and systemic reactions after shots.
- Regular visits – Appointments are needed for shots, prescription refills, dose adjustments.
- Commitment – Treatment takes substantial time, effort and cost over 3-5 years.
Allergy shots involve a major commitment. Make sure to fully discuss what’s involved with your allergist.
Types of Allergic Reactions
Two types of allergic reactions can potentially occur with allergy shots:
Local Reactions
Local reactions affect the area around the injection site. They are generally mild and very common with allergy shots. Local reactions can include:
- Redness, swelling, itching at injection site
- Soreness or tenderness at injection site
Local reactions usually start within 30 minutes after the shot and last 1-2 days. Using ice on the site can provide symptom relief.
Systemic Reactions
Systemic reactions affect parts of the body distant from the injection site, like the respiratory system. They occur less commonly than local reactions but can potentially be severe. Systemic reactions can include:
- Hives, itchy rash, swelling away from injection site
- Runny nose, congestion, sneezing
- Wheezing, coughing, shortness of breath
- Dizziness, fainting, racing heartbeat
- Nausea, vomiting, diarrhea
- Anaphylaxis (life-threatening reaction involving multiple symptoms)
Systemic reactions are most likely to happen during the build-up phase. Patients are monitored closely after shots to watch for any concerning symptoms.
Risks and Contraindications
While allergy shots are generally safe when properly administered, there are some risks and contraindications to be aware of.
Risks
- Local reactions like swelling at the injection site
- Systemic allergic reactions like hives, asthma flares, or rarely anaphylaxis
- Anaphylactic reactions occur in about 1 of every 1 million allergy shots
These risks can be minimized by following the injection schedule and monitoring after shots. First injections are given in the allergist’s office in case of a reaction.
Contraindications
Allergy shots may not be appropriate for patients with certain conditions including:
- Uncontrolled or severe asthma
- Heart conditions like unstable angina or recent heart attack
- Serious immune system diseases
- Pregnancy
- Age less than 5 years old
Allergy shots also cannot be given to patients taking beta blocker medication due to risks of impaired breathing during anaphylaxis.
Home Administration
After reaching the maintenance dose and having no reactions, some patients can continue shots at home for convenience. This is a potential option if the patient:
- Has a well-controlled allergy condition
- Had no prior systemic reactions
- Is trained to self-administer injections properly
- Keeps epinephrine on hand in case of anaphylaxis
Even with home administration, regular doctor’s appointments are still needed to monitor progress and provide new serum prescriptions.
Stopping Allergy Shots
There are circumstances when allergy shots may need to be temporarily halted or discontinued completely:
- Severe local reaction at injection site
- Repeated systemic allergic reactions to shots
- Missing scheduled injections for an extended time
- Changes in medical status like pregnancy or certain illnesses
- Completion of the recommended 3-5 year treatment course
When stopping allergy shots after long-term treatment, symptoms generally do not recur right away. However, allergy relief may gradually diminish over subsequent years without ongoing exposure to the allergens.
Conclusion
Allergy shots provide long-term reduction in allergy symptoms after 3-5 years of regular injections. The shots contain extracts of the allergens triggering an individual’s sensitivities. Doses start very low and gradually increase to a maintenance level that is sustained for years. Though allergy shots are a major commitment, they can provide lasting allergy relief after discontinuing treatment.
