Allergic diseases are a common health problem nowadays, affecting the quality of life of many patients, whether it is sneezing, runny nose, itchy eyes, atopic dermatitis, or asthma. Many people may think they have to live with allergies for life, but currently, there is an effective treatment called “Allergen Immunotherapy” or allergy vaccine treatment.
What is allergen immunotherapy or allergy vaccine treatment? This article will take you to learn about allergen immunotherapy in detail so that you can decide on the most suitable treatment method for yourself.
What is allergen immunotherapy (Allergen Immunotherapy)?
Allergen immunotherapy or allergy vaccine treatment is the process of gradually and regularly introducing allergens into the body to induce immune changes, allowing the body to better tolerate the allergen, which results in improved allergy symptoms or prevents symptoms from occurring again.
This method is like “training” the immune system to become familiar with allergens, making the body less allergic or not allergic at all eventually. Allergy vaccine treatment is the only method that can address the root cause of allergies, not just relieve symptoms.
How allergy vaccines work
- Immune response development: When exposed to small amounts of allergens, the body gradually builds resistance to those substances, causing changes in immune levels.
- Symptom reduction: Increasing immunity helps reduce allergy symptoms in the long term, allowing the body to better tolerate allergens.
Understanding allergic diseases
Allergic diseases occur when the body’s immune system reacts to harmless substances such as dust mites, cockroach debris, cat hair, pollen, and mold, mistakenly identifying them as threats.
When the body comes into contact with allergens, the immune system releases various chemicals, especially histamine, to fight them, resulting in allergy symptoms such as:
- Sneezing, runny nose, nasal congestion
- Itchy eyes, red eyes, watery eyes
- Itchy skin rash
- Asthma, difficulty breathing
- Cough, sore throat
Allergic diseases can significantly affect quality of life, work, study, and daily activities, such as causing poor sleep, chronic headaches, and potentially leading to depression if not properly treated.
What are the treatment options for allergies?
There are several treatment methods for allergies, which can be divided into three main approaches as follows:
1. Avoiding allergens
This is the best preventive method but may be difficult or impossible in some cases, such as completely avoiding pollen or dust mites.
2. Medication treatment
This is the most commonly used treatment, including antihistamines, nasal sprays, bronchodilators, and steroids. These medications can relieve symptoms well but only provide temporary relief; symptoms may return after stopping the medication.
3. Allergen immunotherapy (Allergy vaccine treatment)
This is the only method that can modify the immune system’s response and address the root cause, allowing patients to recover from allergies or reduce symptom severity sustainably, even after stopping treatment.
Who is suitable for allergen immunotherapy?
Allergen immunotherapy has clear indications and is suitable for patients with the following conditions:
- Allergic rhinitis
- Allergic asthma, especially in patients with poorly controlled symptoms using conventional medications
- Atopic dermatitis
- Severe allergic reactions to insects such as bees, wasps, hornets, or ants (Hymenoptera hypersensitivity)
These allergic diseases are caused by allergens proven by allergy testing through skin prick tests or blood tests. Allergens that have been proven effective in treatment include dust mites, cockroaches, mold, allergens from cats/dogs, and pollen from grass, weeds, and trees.
How many types of allergy vaccines are there?
Currently, there are two main types of allergy vaccines widely used, each with different administration methods and pros and cons.
- Subcutaneous Immunotherapy (SCIT)
- Sublingual Immunotherapy (SLIT)
Subcutaneous Immunotherapy (SCIT)
Subcutaneous immunotherapy is the oldest and most scientifically supported treatment method. It involves injecting allergens directly under the skin and can treat multiple allergies simultaneously.
1. How to use:
During the initial 6 months, the doctor gradually increases the dose weekly until reaching the therapeutic dose. After that, patients receive injections every 3–4 weeks and should continue all scheduled injections.
The injection schedule may vary per patient due to different sensitivities or risk factors for side effects. Therefore, patients should be observed in the hospital for at least 30 minutes after each injection.
2. Treatment duration:
Subcutaneous immunotherapy usually lasts about 3–5 years before considering stopping injections. Skin allergy test results may be used to help decide when to stop.
3. Important notes after injection:
Avoid exercising or using the arm where the injection was given before and after the shot. If feeling unwell or having a fever, inform the doctor or nurse before treatment, as the injection may need to be postponed temporarily.
Sublingual Immunotherapy (SLIT)
Sublingual immunotherapy is a convenient and safe form, consisting of drops or tablets placed under the tongue to allow allergens to be absorbed through the mucous membrane into the bloodstream.
How to use:
Patients can self-administer the sublingual tablets at home, taking one tablet daily at the same dose for 3 years. Treatment effects usually appear after about 3–6 months of continuous use.
The first dose should be observed for at least 30 minutes after administration as per instructions.
Side effects of treatment
Generally, subcutaneous allergy vaccines may have more side effects compared to sublingual vaccines.
Side effects of subcutaneous allergy vaccines
1. Itching or redness and swelling at the injection site may occur. If the swelling is larger than 4 cm, inform the staff before the next allergy vaccine injection.
Systemic reactions occur in about 1% of cases, such as rash and itching all over the body. Severe allergic reactions or anaphylaxis occur approximately 1–4 times per million injections. These reactions usually occur within 30 minutes after injection, so patients must be observed in the hospital for at least 30 minutes after the shot.
Patients at risk for these side effects include:
• Patients with untreated high blood pressure
• Patients taking β-blockers for blood pressure control
• Patients with uncontrolled asthma
• Patients with heart disease
Therefore, these patients should inform their doctor before treatment.
Side effects of sublingual allergy vaccines: itching or swelling of the lips, tongue, or palate
2. Burning sensation in the mouth and mild sore throat
These side effects occur about 0.68 times per 1,000 doses. They are usually localized to the area where the medication is applied and typically improve within 2–3 weeks of treatment.
Severe allergic reactions or anaphylaxis are very rare worldwide, about 1 case per 100 million doses. Sublingual vaccines have limitations in patients with a history of fish allergy or foods containing fish. If there are oral wounds from tooth extraction, oral surgery, oral infections, or sores, these conditions must be fully treated before resuming sublingual vaccine treatment, both for new and ongoing patients.
Comparison of sublingual vs. subcutaneous allergy vaccines
| Comparison Item | Sublingual Immunotherapy (SLIT) | Subcutaneous Immunotherapy (SCIT) |
| Administration method | Sublingual at home | Injection at hospital |
| Frequency | Daily | Injection every 3–4 weeks |
| Safety | Highly safe, severe allergic reactions are very rare | Safe, but higher chance of severe allergic reactions than SLIT |
| Cost | Higher in the long term | Lower cost |
| Effectiveness | Good, supported by scientific evidence | Very good, most evidence available |
Advantages of allergy vaccine injections
Allergy vaccine injections have many advantages that make them popular.
1. Addresses the root cause:
It is the only method that can modify the immune system’s function, making the body permanently less allergic or non-allergic, not just temporarily relieving symptoms.
2. Long-lasting treatment effects:
After stopping treatment, most patients maintain improvement similar to during treatment. However, a small portion (33%) may experience symptom recurrence within 1–3 years. These patients can restart vaccine treatment with good results.
Sublingual vaccine treatment usually shows improvement about 2–3 months after starting. If no improvement occurs after 1 year, continuing SLIT is not recommended. If improvement is seen, it is recommended to continue for 3 years.
3. Improves quality of life:
Patients can live normally without avoiding situations or activities for fear of allergy attacks. They can work, study, and exercise fully.
Choosing between subcutaneous or sublingual allergy vaccines should be done with a doctor, considering symptom severity, allergen type, treatment readiness, and other relevant factors.
Precautions for allergy vaccines
Allergy vaccines, whether subcutaneous or sublingual, should not be started in pregnant women. However, if a patient becomes pregnant during ongoing treatment, they can continue the vaccine but must inform the doctor immediately.
Preparation before allergy vaccine injection
- Get enough rest, 6–8 hours of sleep
- Avoid exercise 2 hours before and after allergy vaccine injection
- If planning pregnancy or currently pregnant, inform the doctor
- Patients with chronic diseases should consult a specialist before allergy vaccine injection
- If feeling unwell or sick, inform or consult a doctor to consider postponing the allergy vaccine injection
Summary of allergen immunotherapy treatment
Allergen immunotherapy is an effective treatment and the only method that truly addresses the root cause of allergies, not just temporarily relieving symptoms. This treatment enables the body to build tolerance to allergens, allowing patients to live normally without relying on antihistamines all the time.
If you are suffering from allergies and want a sustainable treatment option, allergen immunotherapy may be the answer you are looking for. Consult an allergy specialist to assess suitability and choose the best treatment method.
Dr. Krittecho Siripatsorn
Specialist in Allergy and Clinical Immunology
Internal Medicine Center
