Immune Disorder

• Seasonal allergic rhinitis is an immune disorder characterized by allergic reactions to pollen of trees, grasses, weeds, mold or fungal spores. The immune system of a person with allergic rhinitis recognizes harmless pollens or other allergens as harmful substances.
  
  

Allergic Reaction

• When allergens enter the body the immune system releases large amounts of histamines and leukotrienes, which cause the typical runny nose, sneezing, itchy throat and watery, itchy eyes. Symptoms are typically worse after being outdoors.
  
  

Common Triggers

• Hay fever in the spring is most likely caused by tree pollen. Allergies in the summer may be caused by grass and weed pollens. Ragweed is a common trigger in the fall, and mold and fungal spores are typical culprits from November through March.
  
  

An Inherited Trait

• Increased allergic sensitivity is an inherited trait. Most people with allergic rhinitis have a parent or sibling with the same condition. A family history of allergic rhinitis increases the risk of developing seasonal allergies.
  
  

Onset

• The onset of allergic rhinitis usually occurs from childhood to early adulthood, although it can show up at any age. Up to 20 percent of children and as many as 30 percent of adolescents have seasonal allergies. The condition is more common in boys.