Allergen Immunotherapy - Side Effects and Adverse Reactions

Side Effects and Adverse Reactions

Subcutaneous immuno-therapy (SCIT)

While itchiness, swelling, and redness at the site of injection are expected, systemic reactions such as hives or anaphylaxis rarely occur. A July 2011 study following 773 patients that collectively received approximately 28,000 injections, the rate of systemic reaction to SCIT was about 4%. As such, patients are advised or required to wait in the clinic for 20–30 minutes so that they can be treated immediately in the case that they develop a severe systemic reaction. However, a 2008 study found that just under 50% of reported systemic reactions occurred more than 30 minutes after the injection.

Premedication with antihistamines or corticosteroids can reduce the risk of systemic reaction.

There is an established correlation between those receiving a Rushed Immunotherapy and higher rates of systemic reactions as compared to that those receiving conventional SCIT. While it may seem attractive to patients to rush SCIT, it seems as though it does lead to an increased risk to having a systemic reaction. However, this may not be the same for allergic respiratory diseases.

About 74% of systemic reactions to SCIT are mild reactions such as cutaneous or upper respiratory symptoms; about 23% are moderate reactions such as asthma with reduced lung function, and about 3% are severe, where life-threatening airway compromising or hypo-tension occurs.

Based on the highest reported symptoms of a systemic reaction, such as generalized itching, upper airway itchiness, coughs, or a shortness of breath should be reported immediately so they can be monitored or managed. These are usually managed through the use of epinephrine.

If such reactions occur, the allergy specialist will adjust the dosage to a safe level. The risk of a systemic reaction is reduced if the patient avoids exercising or overheating for a few hours before and after the procedure. Some heart and blood pressure medications such as beta-blockers are contraindicated as well.

The physician should be consulted if the patient notices a worsening of allergy symptoms or if he or she is suffering from a cold or has been undergoing a different kind of vaccination procedure. Immunotherapy does not increase the risk of contracting a cold.

Itchiness and warm skin may occur sparadically on the place of the injections for many years after treatment have ended.

Sublingual immuno-therapy (SLIT)

The side effects of sublingual desensitisation therapy are generally mild and limited to local reactions. Common side effects include oral pruritus, edema mouth, ear pruritus, throat irritation, sneezing, mild itching and swelling of the mouth. Side effects which are less common or rare include headache, oral paraesthesia, eye pruritus, conjunctivitis, cough, asthma, pharyngitis, rhinorrhoea, nasal congestion, rhinitis, throat tightness, pruritus and fatigue. In most cases these side effects diminished minutes or hours after immunotherapy and disappeared 1 – 7 days after commencement of therapy. As a precautionary measure against rare but serious side effects e.g. asthma attacks it is recommended that the first sublingual tablet containing the specific allergen for immunotherapy is administrated whilst under the observation of a medical doctor and observed for 30 minutes for any signs of serious side effects.

Sublingual immunotherapy is contraindicated in patients who have systemic diseases of the immune system, inflammatory conditions of the oral cavity with associated severe symptoms e.g. oral lichen planus with ulcers or severe oral mycosis or individuals with severe and uncontrolled asthma. Immunotherapy tablets are also contraindicated in individuals who are allergic to any of the addition constituents of the tablet.