What Is Allergic Rhinitis? Allergic Rhinitis is an inflammation of the nasal lining caused by allergens such as, pollen, house dust mite, general dust, mould, animals and certain foods. Hayfever forms part of the spectrum. It is a common condition, affecting 1 in 5 people in the UK. Signs & Symptoms Typically the symptoms mimic a common cold and include but are not limited to: Blocked and or a runny nose