Allergic conditions: introduction

Allergic conditions occur when the immune system reacts to a typically harmless foreign substance that has entered the body, known as an allergen (Mayo Clinic). Allergens, the symptoms they cause and consequently their impact on health are complex and varied. Most conditions cause only minor symptoms; however some may be chronic and disabling, including asthma, eczema or urticaria (hives); and rarely allergies can cause life-threatening anaphylaxis (see section on Determinants for further information on conditions and symptoms). This complexity and variety also make it challenging for clinical researchers to generalise findings to the population in order to inform diagnosis, prognosis and treatment (Papadopoulos, 2020; Bellanti & Settipane, 2023).

Diagnosis of an allergic condition involves various assessments. First, a GP will ask questions about the suspected allergy, including potential allergens, symptoms caused and the setting of allergic reaction (e.g. at school/home) (National Institute for Health and Care Excellence (NICE), 2024). While a GP may diagnose simpler or less severe allergies such as allergic rhinitis (hayfever), complex allergies may require further testing in a specialist allergy clinic, such as skin patch tests or blood tests (NHS, 2022).

Management of allergies primarily involves developing strategies to avoid the allergen where possible. However, medicines such as antihistamines, decongestants, steroids and lotions for skin allergies may be recommended. For sufferers of severe allergic reactions, such as those that cause anaphylaxis, adrenaline auto-injectors such as EpiPens may be carried. In cases of severe allergy, immunotherapy, where an individual receives gradually increasing doses of their allergen, may be used to desensitise an individual (NHS, 2022).

Studies exploring the wider impact of allergic conditions are scarce at both Scotland- and UK-level; however a 2020 global review by Dierick et al found that allergic conditions including asthma, allergic rhinitis, atopic dermatitis and food allergies reduced sufferers’ quality of life and incurred indirect costs through loss of productivity due to presenteeism. Similarly, it was estimated that 100 million work and school-days were missed in Europe due to allergies every year, with potential savings of €142 billion if those with allergies were appropriately treated with available cost-effective treatments (European Academy of Allergy and Clinical Immunology (EAACI), 2015).