Allergic conditions: determinants

Some allergies are thought to be heritable to some degree. For example, genetic factors are thought to contribute to asthma by increasing sensitivity of the airways (see ScotPHO section on Asthma Risk Factors).

The complex and multifactorial nature of allergies means that interactions between allergies can often be observed. One such example is the so-called “atopic triad” of asthma, rhinitis and eczema: a pattern whereby atopic dermatitis manifests in infancy followed by allergic rhinitis and asthma in subsequent years (Spergel, 2010). Further research is required to understand how exactly onset of one allergy can trigger onset of another.

To some extent, the risk of allergic conditions is related to the level of exposure of the population to allergens. The factors that determine the risk of an abnormal response to allergens are less well understood, although there is likely to be a genetic component as some families have a predisposition to allergies (known as atopy) where allergic parents are more likely to have allergic children.

Common allergic conditions, their causes and symptoms as reviewed by the NHS (2022) include: