[Pemphigoid reaction by specific allergen immunotherapy: An unusual adverse reaction]

For the most part, adverse reactions caused by subcutaneous allergen-specific immunotherapy (AIT) are directly induced by the administration of an allergen; there is usually redness and induration at the area of the injection. Other skin lesions are extremely unusual.

A 40-year-old woman with allergic rhinoconjunctivitis and asthma due to sensitization to grass pollen had received monthly doses of 0.5mL of a subcutaneous polymerized extract of grass pollen with glutaraldehyde and adsorbed in aluminum hydroxide. Five hours after the seventh dose, the patient presented stinging and itching at the area of the injection of the immunotherapy, together with a blistering reaction that appeared later.

Although adverse reactions by allergen-specific immunotherapy are rare and difficult to verify, it is important to perform the necessary analyses to identify the causes or their relation to the symptoms to avoid reactions in the future.