Allergic conditions: determinants

Allergic conditions arise from an abnormal response to foreign substances (allergens) which are typically harmless to the general population. These include, but are not limited to:

• grass
• weed and tree pollens
• house dust
• fungal spores
• animal products
• foods e.g. nuts, shellfish
• drugs e.g. vaccines, anaesthetics
• chemicals

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.