Seasonal Allergies: Causes
Allergic rhinitis is the set of symptoms that occurs when you breathe in substances you are allergic to. These substances are called allergens and are small proteins.
- Seasonal (intermittent) allergic rhinitis (sometimes called hay fever or rose fever)—This occurs during times of the year when allergens are in the air, like spring, summer, and fall. The most common allergens are tree, grass, or weed pollens.
- Perennial (persistent) allergic rhinitis—This condition is caused by allergens that may be present year round. These may include chemicals, dust, dust mites, cockroaches, animal dander, or mold spores. Symptoms may be present any time of year.
An allergic reaction occurs when your body's immune system overreacts to an allergen. When you breathe in an allergen, cells in your nasal passages release a chemical called histamine. Histamine causes your nose to feel itchy. Histamine also causes swelling and mucus production in the nasal passages.
Site of Histamine Production
Copyright © Nucleus Medical Media, Inc.
Last reviewedSeptember 2013by Marcin Chwistek, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.