How can I differentiate between allergic rhinitis and non-allergic rhinitis in a patient presenting with nasal symptoms?

To differentiate between allergic rhinitis and non-allergic rhinitis in a patient presenting with nasal symptoms, a detailed clinical history and targeted investigations are essential. Allergic rhinitis typically presents with symptoms triggered by specific allergens such as pollen, house dust mites, or animal dander, often showing a seasonal or perennial pattern depending on the allergen exposure. Patients commonly report sneezing, nasal congestion, rhinorrhoea, and nasal itching, often accompanied by ocular symptoms like itchy, watery eyes. A history of atopy or other allergic conditions supports the diagnosis. In contrast, non-allergic rhinitis presents with similar nasal symptoms but without a clear allergen trigger and often lacks associated ocular symptoms. It may be perennial and triggered by irritants such as smoke, strong odors, or changes in weather rather than allergens ¹.

Objective confirmation of allergic rhinitis involves allergy testing, such as skin prick tests or specific IgE blood tests, to identify sensitisation to relevant allergens. A positive test supports allergic rhinitis, whereas negative allergy tests in the presence of rhinitis symptoms suggest non-allergic rhinitis ¹. However, local IgE production in nasal mucosa without systemic sensitisation has been described in some non-allergic rhinitis cases, indicating a complex pathophysiology (Campo et al., 2015).

Physical examination may reveal pale, bluish, or boggy nasal mucosa in allergic rhinitis, while non-allergic rhinitis may show erythematous mucosa. Nasal cytology can sometimes help differentiate by identifying eosinophils in allergic rhinitis and neutrophils or mast cells in non-allergic rhinitis (Sacre Hazouri, 2010).

In summary, differentiation relies on clinical history focusing on symptom triggers and patterns, supported by allergy testing to confirm or exclude allergen sensitisation. Non-allergic rhinitis is diagnosed when symptoms persist without evidence of allergen sensitisation and may require exclusion of other causes ¹ (Kemp, 2009; Sacre Hazouri, 2010; Campo et al., 2015).