Allergy immunotherapy, often called desensitisation or hypo-sensitisation, is a medical treatment that reduces the immune system’s sensitivity to specific allergens. This therapy is particularly beneficial for individuals who suffer from severe allergic reactions or whose symptoms are not adequately controlled by conventional medications. Here’s an in-depth look at allergy immunotherapy, including its types, mechanisms, benefits, risks, and what to expect during treatment.
Types of Allergy Immunotherapy
There are two main types of allergy immunotherapy: subcutaneous immunotherapy (SCIT) and sublingual immunotherapy (SLIT).
Subcutaneous Immunotherapy (SCIT)
SCIT, commonly known as allergy shots, involves regular injections of allergen extracts under the skin.
Procedure
- Initial Phase – During this phase, injections are given one to three times per week, with gradually increasing doses of the allergen.
- Maintenance Phase – Once the effective dose is reached, injections are spaced out to once every two to four weeks. This phase typically lasts for three to five years.
Common Allergens Treated
- Pollen (trees, grasses, weeds)
- Dust mites
- Animal dander
- Mold spores
- Insect stings
Sublingual Immunotherapy (SLIT)
SLIT involves placing a tablet or liquid containing the allergen under the tongue, where it is absorbed into the bloodstream.
Procedure
- Tablets or Drops – Taken daily at home, SLIT usually starts with a lower dose that is gradually increased.
- Duration – Like SCIT, SLIT is typically continued for several years to achieve long-term benefits.
Common Allergens Treated
- Grass pollen
- Ragweed pollen
- Dust mites
Mechanism of Action
Allergy immunotherapy works by gradually exposing the immune system to increasing amounts of the allergen, which helps to build tolerance and reduce the severity of allergic reactions.
Immune System Changes
- Reduction of IgE Production – IgE antibodies are responsible for allergic reactions. Immunotherapy reduces the production of these antibodies over time.
- Increase in Regulatory T Cells – These cells help to regulate the immune response and reduce inflammation.
- Shift in Immune Response – The therapy shifts the immune response from an allergic (Th2) response to a non-allergic (Th1) response.
Benefits of Allergy Immunotherapy
Allergy immunotherapy offers several advantages, especially for those with persistent and severe allergies.
Long-Term Relief
Unlike medications that only manage symptoms, immunotherapy addresses the underlying cause of allergies, providing long-term relief even after treatment has ended.
Reduced Medication Dependence
Patients often experience a decreased need for allergy medications, such as antihistamines and corticosteroids, as their symptoms improve.
Improved Quality of Life
By reducing symptoms and improving tolerance to allergens, immunotherapy can significantly enhance the quality of life for allergy sufferers.
Prevention of New Allergies
Immunotherapy may also prevent the development of new allergies and reduce the risk of asthma in children with allergic rhinitis.
Risks and Side Effects
While allergy immunotherapy is generally safe, it does come with some risks and potential side effects.
Local Reactions
- SCIT – Redness, swelling, and itching at the injection site are common but usually mild.
- SLIT – Itching or swelling in the mouth and throat can occur.
Systemic Reactions
More severe reactions, though rare, can include:
- Anaphylaxis – A serious, potentially life-threatening allergic reaction that requires immediate medical attention. For this reason, SCIT is administered in a medical setting where emergency treatment is available.
- Mild Systemic Symptoms – Such as hives, nasal congestion, or mild asthma symptoms.
Monitoring and Safety
Patients undergoing SCIT are observed for 30 minutes after each injection to monitor for adverse reactions. SLIT patients should follow their allergist’s guidelines and have emergency medication, like an epinephrine auto-injector, on hand.
What to Expect During Treatment
Understanding what to expect during allergy immunotherapy can help patients prepare for and commit to the process.
Initial Consultation
- Assessment – The allergist will conduct a thorough medical history, physical examination, and allergy testing to determine the specific allergens causing symptoms.
- Discussion – The risks, benefits, and commitment required for immunotherapy will be discussed.
Treatment Plan
- Custom Allergen Extract – A personalized treatment plan with a custom allergen extract will be created based on the patient’s specific allergies.
- Regular Appointments – SCIT requires regular visits to the allergist’s office, whereas SLIT can be administered at home under guidance.
Progress Monitoring
- Regular Follow-Ups – Ongoing monitoring and adjustments to the treatment plan will be made based on the patient’s response.
- Symptom Tracking – Patients are encouraged to keep a symptom diary to track improvements and any side effects.
Treatment Plan
- Long-Term Commitment – Both SCIT and SLIT require a commitment of several years to achieve maximum benefits.
Allergy immunotherapy is a highly effective treatment for those suffering from persistent and severe allergies. By gradually building tolerance to allergens, this therapy offers long-term relief, reduces dependence on medications, and improves overall quality of life. While there are risks and a significant time commitment involved, the potential benefits make it a valuable option for many allergy sufferers. Consultation with an allergist can help determine if immunotherapy is the right choice for managing your allergies.
