Perennial allergic rhinitis may be defined clinically as an inflammatory condition of the nose characterised by nasal obstruction, sneezing, itching, or rhinorrhoea. It occurs due to an exaggerated response to an environmental trigger which results in inflammation of the lining of the nose; it is similar to hayfever, however, the substances which cause the allergic reaction are present all year round; common causes include the faecal matter of the house dust-mite (Dermatophagoides pteronyssinus), animal proteins from domestic pets (saliva or skin proteins), and industrial dusts and fumes In those with perennial rhinitis, cigarette smoke, washing powders, detergents, strong perfume, and traffic fumes may exacerbate the condition.