How do hay fever treatments actually work? And what’s best for my symptoms?

Spring has sprung and many people are welcoming longer days and more time outdoors. But for almost one in five Australians, spring also brings the misery of watery, itchy red eyes, a runny, congested nose, and sneezing.

Hay fever (also known as allergic rhinitis) is caused when an allergen enters the nose or eyes. Allergens are harmless airborne substances the body has incorrectly identified as harmful. This triggers an immune response, which leads to the release of inflammatory chemicals (mediators) – one of which is histamine.

Allergens that trigger hay fever differ from person to person. Common seasonal allergens include tree, grass and weed pollens (year-round allergens include dust mites, mould and pet dander). It’s now pollen season in many parts of Australia, with pollen counts at their highest and hay fever cases surging.

So what medicines can prevent or reduce hay fever symptoms, and how do they work?