What Causes Allergic Rhinitis in Babies?

Allergic rhinitis in infants—often referred to as “baby hay fever”—is an immunoglobulin E (IgE)-mediated hypersensitivity reaction triggered by exposure to environmental allergens. Unlike older children and adults, infants rarely present with classic seasonal symptoms; instead, they may exhibit persistent nasal congestion, sneezing, watery rhinorrhea, nasal pruritus, or recurrent ear infections due to eustachian tube dysfunction.

The most common sensitizing agents in this age group include indoor aeroallergens—particularly house dust mites, pet dander (especially from cats and dogs), and mold spores. While pollen-induced allergic rhinitis is uncommon before age two, early sensitization can occur in genetically predisposed infants with a strong family history of atopy. Maternal atopy, especially maternal asthma or allergic rhinitis, significantly increases the infant’s risk of developing IgE-mediated sensitization.

It is critical to distinguish allergic rhinitis from nonallergic causes of nasal symptoms in infancy—including viral upper respiratory infections (the most frequent cause), gastroesophageal reflux disease (GERD), anatomical anomalies such as choanal atresia, or primary ciliary dyskinesia. Diagnostic evaluation typically begins with a detailed clinical history and physical examination; skin prick testing or serum-specific IgE assays may be considered after six months of age if clinical suspicion remains high and symptoms are persistent, unresponsive to standard supportive care, and associated with other atopic manifestations like eczema or food allergy.

Management emphasizes allergen avoidance strategies—such as using dust-mite-proof mattress encasings, reducing indoor humidity to inhibit mold and mite proliferation, and minimizing direct pet contact—alongside saline nasal irrigation for symptom relief. Pharmacologic intervention is generally reserved for moderate-to-severe cases and requires careful pediatric dosing; intranasal corticosteroids are not routinely recommended under age two due to limited safety data, while second-generation oral antihistamines may be used off-label under specialist guidance.