What Causes Allergic Rhinitis? Triggers, Allergens, and Risk Factors Explained

Major Causes of Allergic Rhinitis: Outdoor Allergens

Outdoor allergens are among the most common causes of allergic rhinitis, particularly pollen released from trees, grasses, and weeds. The pollen from tree sources such as oak, birch, and cedar is most common in the spring season; the pollen from grasses increases in the summer; and the ragweed pollen remains the main cause of allergic rhinitis during the latter part of summer and the beginning of fall. These airborne spores can easily enter the mouth, nose, and eyes, producing mucous membrane inflammation. Certain people only get hay fever during specific seasons of the year because of seasonal variation.

 Indoor Allergens That Cause Perennial Allergic Rhinitis

Perennial allergic rhinitis is a persistent condition mostly brought on by indoor exposures. One of the main causes is house dust mites, which flourish in upholstered furniture, carpets, and mattresses. Their body flakes and small waste particles cause allergies. Pet dander, which is made up of small skin cells, fur, or saliva from dogs, cats, or other animals, may cause long-lasting symptoms, particularly if pets are housed together. Other indoor causes include mold, cockroach remains, and mold spores, especially in moist spaces like basements or bathrooms. Nasal stuffiness, sneezing, sinus congestion, and occasionally ear disorders or conjunctivitis (eye allergies) might result from inhaling these irritants.Continuous exposure to these indoor allergens often leads to persistent nasal symptoms and is a major cause of perennial allergic rhinitis.

  Environmental and Occupational Irritants that Trigger Symptoms

In addition to true allergens, environmental and occupational irritants can worsen allergic rhinitis symptoms in susceptible individuals.Contrary to traditional allergies, chemical irritants can exacerbate symptoms in some people. Frequent exposure to latex, wheat dust, wood dust, perfumes, cleaning supplies, or industrial pollutants  irritate nasal tissues and cause an allergic-like inflammatory reaction. Active and passive cigarette smoke is a well-known irritant that exacerbates allergic inflammation and impairs the body’s natural mucociliary defense. Similarly, air pollution, smells, and volatile organic compounds (VOCs) in home items exacerbate symptoms and enhance airway sensitivity.

Why Some People Are More Sensitive: Genetics and Immune Factors

Genetic predisposition plays a significant role in allergic rhinitis. Individuals with a family history of allergies, asthma, or eczema are more likely to develop nasal allergies.
Early-life exposure patterns, immune system development, and repeated allergen contact increase sensitivity over time, making some individuals more prone to persistent or severe symptoms.These factors together represent key risk factors for allergic rhinitis development.

Lifestyle and Home Factors That Increase Allergy Risk

Living in an urban area nowadays increases exposure to irritants, including synthetic chemicals, vehicle exhaust, and poor indoor air quality. Allergen loads are increased by poor ventilation, high humidity, and dust buildup in bedding and carpets. Nasal sensitivity can also be made worse by scents from cleaning products or perfumes. On the other hand, these problems can be managed by keeping a clean, properly ventilated home, utilizing HEPA filters, and reducing indoor humidity.Modern lifestyle patterns, including increased time spent indoors and reduced ventilation, further contribute to rising allergy risk.