How can I differentiate between allergic rhinitis and other causes of nasal symptoms in patients?

Differentiating between allergic rhinitis and other causes of nasal symptoms in patients primarily relies on a detailed allergy-focused clinical history, physical examination, and consideration of specific red flag features ¹,³.

• Typical Presentation of Allergic Rhinitis: Allergic rhinitis commonly presents with upper respiratory tract symptoms such as nasal itching, sneezing, rhinorrhoea (runny nose), or congestion, which may or may not be accompanied by conjunctivitis (itchy, watery eyes) ³. These symptoms can be seasonal, often linked to pollen (tree, grass, or weed pollens), or perennial, typically associated with house dust mites or animal dander ¹.
• Key Differentiating Factors from Clinical History:
  • Atopic History: Inquire about any personal history of atopic diseases, such as asthma, eczema, or allergic rhinitis, as well as a family history of atopic disease or food allergy in parents or siblings ³.
  • Symptom Characteristics: Ascertain the age of onset, speed of symptom development following exposure, duration, severity, frequency, and reproducibility of symptoms upon repeated exposure to suspected allergens ³. For instance, IgE-mediated allergic reactions often have an immediate and rapid onset ³.
  • Triggers and Exposure: Identify specific triggers, such as exposure to pollen, house dust mites, or pets, and note if symptoms align with specific seasons or environments ¹.
  • Response to Treatment: Consider how symptoms have responded to previous treatments, including over-the-counter medications ¹,³.
• Physical Examination: Pay attention to growth and physical signs of malnutrition, and look for signs indicating allergy-related comorbidities like atopic eczema or asthma ³.
• Excluding Other Causes and Red Flag Features: It is crucial to consider other causes, particularly when certain red flag features are present, which warrant specialist referral ¹. These include:
  • Unilateral Symptoms: Nasal symptoms affecting only one side of the nose ¹.
  • Blood-stained Nasal Discharge or Recurrent Epistaxis: Presence of blood in nasal discharge or frequent nosebleeds ¹.
  • Nasal Pain: Persistent or significant pain in the nasal area ¹.
  • Predominant Nasal Obstruction or Structural Abnormality: If nasal blockage is the main symptom or if there's a suspected structural issue like a deviated nasal septum, which can make intranasal drug treatment difficult ¹.
  • Persistent Symptoms Despite Optimal Management: If symptoms do not improve with appropriate primary care management ¹.
  • Uncertain Diagnosis: If the diagnosis remains unclear after initial assessment ¹.
• Consideration of Other Allergic Conditions:
  • Food Allergy: Nasal symptoms can occur as part of a food allergy, especially in children and young people, but they are usually accompanied by other symptoms affecting the skin (e.g., urticaria, eczema), gastrointestinal system (e.g., vomiting, diarrhoea), or lower respiratory tract (e.g., cough, wheezing) ³.
  • Drug Allergy: Nasal symptoms could also be part of a drug-induced allergic reaction, in which case the suspected drug should be stopped and the reaction documented ⁴.
  • Local Allergic Rhinitis: Be aware of local allergic rhinitis, where symptoms are confined to the nose without systemic allergic manifestations (Campo et al., 2019).
• Diagnostic Testing: If IgE-mediated allergy is suspected based on the clinical history, skin prick tests and/or blood tests for specific IgE antibodies to suspected foods and co-allergens may be offered ³. These tests are also considered when the diagnosis is uncertain or when allergen avoidance techniques are being considered ¹. Such tests should only be undertaken by healthcare professionals with appropriate competencies and facilities to manage anaphylaxis ³.