The two main types of seasonal allergens are pollen and molds. The type of pollen present depends on the growing season and the area of the country. Molds may be present year-round, especially in damp spaces of buildings and in furniture, such as mattresses and pillows. A person may be allergic only to molds that are present during one particular season or to all molds. When the pollen or molds come into contact with these tissues in an allergic person, cells in the tissues release a chemical called histamine.
Histamine causes the tissues to itch, swell, and produce more mucus or tears than is normal.
If you have asthma and you breathe into your lungs the substances you are allergic to, symptoms of asthma may be triggered. Common upper respiratory symptoms of hay fever include sneezing runny nose itchy nose, throat, or ear canals ear congestion itchy, watery eyes postnasal drainage. Lower respiratory symptoms that may occur are shortness of breath, especially with exercise or exertion frequent coughing wheezing. The diagnosis of hay fever is usually made from your medical history, based on a seasonal occurrence of symptoms. An ear, nose, throat, and lung exam may confirm the diagnosis.