Risk Factors

Allergic rhinitis affects between 20 and 40 million Americans of all ages. As with asthma and many upper respiratory infections, the incidence in allergic rhinitis is increasing. Allergies most often appear first in childhood, and allergic rhinitis is the most common chronic condition in childhood, although it can develop at any age. About 20% of allergic rhinitis cases are due to seasonal allergies, 40% to perennial (chronic) rhinitis, and the rest are mixed.

Family History

Genetic factors are the major determinants of allergies.

  • If both parents have an allergy, the child's risk is 75%
  • If one parent is allergic, the child's risk is 50%

Having Other Allergies

Having other allergies increases the risk for allergic rhinitis. Here are some examples:

  • Young children who have eczema (an allergic skin reaction) have a later risk for allergic rhinitis and asthma. In fact, a family history of eczema increases the risk.
  • Food allergies are associated with allergic rhinitis and asthma. (Early feeding patterns, time of weaning, and introduction of solid food do not appear to affect this risk.)
  • Asthma, especially in patients who develop it as adults, may increase allergic sensitivity to ragweed and other allergens. Patients who have asthma and a genetic tendency towards allergies (atopy) are also at risk for rhinitis.

Other Factors Associated with Allergies

Birth Month. Some studies report a higher risk of allergies and asthma in children born in winter months and lower risk in those born during the summer.

Breastfeeding. Some researchers suggest that the dramatic increase in asthma and allergies may be due to fewer women breastfeeding their infants. In a number of studies, breastfeeding has been associated with a lower risk for allergies and asthma -- at least until age 2. Breastfeeding can also help prevent other upper respiratory infections. The American Academy of Pediatrics recommends feeding infants exclusively breast milk for the first 6 months of life.

Review Date: 3/17/2006
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital.