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 NICE CKS,NICE CG116.

• 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) NICE CG116. 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 NICE CKS.
• 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 NICE CG116.
  • 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 NICE CG116. For instance, IgE-mediated allergic reactions often have an immediate and rapid onset NICE CG116.
  • 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 NICE CKS.
  • Response to Treatment: Consider how symptoms have responded to previous treatments, including over-the-counter medications NICE CKS,NICE CG116.
• Physical Examination: Pay attention to growth and physical signs of malnutrition, and look for signs indicating allergy-related comorbidities like atopic eczema or asthma NICE CG116.
• 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 NICE CKS. These include:
  • Unilateral Symptoms: Nasal symptoms affecting only one side of the nose NICE CKS.
  • Blood-stained Nasal Discharge or Recurrent Epistaxis: Presence of blood in nasal discharge or frequent nosebleeds NICE CKS.
  • Nasal Pain: Persistent or significant pain in the nasal area NICE CKS.
  • 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 NICE CKS.
  • Persistent Symptoms Despite Optimal Management: If symptoms do not improve with appropriate primary care management NICE CKS.
  • Uncertain Diagnosis: If the diagnosis remains unclear after initial assessment NICE CKS.
• 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) NICE CG116.
  • 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 NICE CG183.
  • 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 NICE CG116. These tests are also considered when the diagnosis is uncertain or when allergen avoidance techniques are being considered NICE CKS. Such tests should only be undertaken by healthcare professionals with appropriate competencies and facilities to manage anaphylaxis NICE CG116.