Immunotherapy

Immunotherapy Overview

Immunotherapy is a long-term treatment that can reduce how strongly your immune system reacts to allergens. Small, gradually increasing doses of the substance you’re allergic to are given over time so your body gets used to it and symptoms improve (Mayo Clinic). Unlike antihistamines or nasal steroids, which only relieve symptoms, immunotherapy targets the underlying allergic response.

Forms of Immunotherapy

There are two main forms: allergy shots (subcutaneous immunotherapy) and sublingual tablets that dissolve under the tongue. Sublingual tablets were approved by the FDA in 2014 and cover only a few allergens, such as certain grass and ragweed pollens and house dust mites (ACAAI). Allergy shots are usually given in the upper arm (Mayo Clinic). How long treatment takes depends on:

• the length of the treatment program,
• the severity of the allergy, and
• the doses of allergens given

Phases of Immunotherapy

The treatment is carried out in generally two phases:

• Build-up phase: generally 3 to 6 months, with shots typically 1 to 3 times a week as the dose is gradually increased (Mayo Clinic).
• Maintenance phase: usually 3 to 5 years or longer, with shots about once a month (Mayo Clinic).

Immunotherapy Effectiveness

Symptoms usually improve during the first year, with the most noticeable improvement often in the second year. By the third year, most people no longer have bad reactions to the allergens, and some stay symptom-free even after shots stop (Mayo Clinic). Allergy shots can treat:

• Seasonal allergies, including hay fever and seasonal allergic asthma from tree, grass and weed pollen (Mayo Clinic)
• Indoor allergies to dust mites, cockroaches, mold and pet dander
• Insect sting allergies (bees, wasps, hornets and yellow jackets). Allergy shots are not available for food allergies or chronic hives.

Failure to respond to immunotherapy shots may be due to several factors, including:

• A low dose of allergen in the allergy vaccine,
• Misidentification of allergens during the allergy evaluation,
• Presence of high levels of allergens in the surrounding environment,
• Exposure to other non-allergic triggers, such as tobacco smoke.

Benefits

Allergy shots may be a good choice if (Mayo Clinic):

• medicines don’t control your symptoms well, or you can’t avoid your triggers,
• you have an insect sting allergy, or allergy medicines interact with other medicines you need,
• allergy medicines cause bothersome side effects, or you want to reduce long-term medicine use.

Side Effects

Most people don’t have much trouble with allergy shots, but reactions are possible (Mayo Clinic):

• swelling and redness,
• itchy skin,
• nasal congestion, and
• sneezing.

Rarely, a shot can cause anaphylaxis, which often begins within 30 minutes. That is why you’re observed in the clinic for at least 30 minutes after each shot. If you were prescribed an epinephrine auto-injector, use it right away for a serious reaction after you leave (Mayo Clinic). Tell the staff if you feel unwell before a shot, especially if you have asthma.

Guidelines

Avoid vigorous exercise for at least a few hours after a shot. Before starting, your doctor will use skin or blood tests to confirm which allergens cause your symptoms. If you skip doses, you may need to go back to lower doses (Mayo Clinic).

Conclusion

Immunotherapy is the one allergy treatment that can provide lasting relief, but it takes commitment: typically 3 to 5 years. Ask an allergist whether shots or tablets are right for you. See how it fits with seasonal triggers in spring allergies and fall allergies.

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Written by: Madiha Ather Hashmi (June 09, 2020)

This article is for general education and is not medical advice. Talk with your doctor or pharmacist about your symptoms and before starting, stopping, or combining any medicine.

Immunotherapy FAQs

How long do allergy shots take to work?

Most people improve during the first year, with the biggest improvement often in year two (Mayo Clinic).

How long is a course of allergy shots?

Usually 3 to 5 years of maintenance after a 3-to-6-month build-up phase (Mayo Clinic).

Are there allergy tablets instead of shots?

Yes. FDA-approved sublingual tablets treat certain grass and ragweed pollens and dust mites (ACAAI).

Why do I have to wait after a shot?

Serious reactions often begin within 30 minutes, so you’re observed for at least 30 minutes (Mayo Clinic).

Sources

Looking for more treatment options? Find a full list of other seasonal allergy treatment options here.