Seasonal allergic rhinitis (SAR). A seasonal allergy
occurs at the same time each year and is often called hay fever. The most
common allergens in seasonal allergies are windblown pollens from trees,
grasses, or weeds, so the symptoms of a seasonal allergy usually occur when
certain plants are in bloom. (Some types of mold also occur seasonally and may
cause similar symptoms.)
Perennial allergic rhinitis (PAR). A year-round
(perennial) allergy occurs any time during the year. The symptoms of a
year-round allergy may be more severe in winter, when people spend more time
indoors. The most common causes of perennial allergies are
animal dander, cockroaches, or mold.
Occupational allergic rhinitis (OAR). Occupational
allergic rhinitis is caused by an allergic reaction to a substance present in
the workplace, such as grain, wood dust, chemicals, or lab animals.