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 NICE CKS.

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 NICE CKS. 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 NICE CKS Kemp 2009Sacre Hazouri 2010Campo et al. 2015.