Allergic rhinitis

• Allergic rhinitis:

  • Environmental allergens cause an allergic inflammatory response in the nasal mucosa
  • Caused by IgE-mediated type 1 hypersensitivity reaction
• Triggers:

  • Tree, grass and weed pollens (hay fever)
  • House dust mites
  • Animal dander (cat and dog hair)
  • Moulds e.g. aspergillus
• Allergic rhinitis may be:

  • Seasonal, for example hay fever
  • Perennial or persistent (year round), for example house dust mite allergy
  • Occupational, associated with the school or work environment
• IgE-mediated antibody response:

  • When an allergen is encountered - IgE antibodies produced
  • IgE antibodies bind to mast cells in preparation for exposure to the allergen again (sensitisation)
  • When the same allergen is encountered again the IgE antibodies attack it, mast cells degranulate and release cytokines (histamine, tryptase etc) - local inflammation, vessel dilatation, oedema
• Can be classified by severity:

  •Mild: Normal sleep, no impairment to ADLs, non-troublesome

  •Moderate-to-severe: One or more of: disturbed sleep, impaired performance (work/school), impaired ADLs, troublesome symptoms
• Allergic rhinitis is often associated with personal or family history of other allergic conditions (atopy) such as:

  • allergic conjunctivitis
  • rhinosinusitis
  • asthma
  • atopic eczema
• Diagnosis:

  • Clinical based on history e.g. symptoms develop within minutes of exposure, personal or family history of atopy
  • Allergy testing is rarely needed but sometimes done:
  • Skin prick testing - observe for cutaneous allergic reaction
  • Blood test of allergen specific IgE antibodies - known as RAST test
• General principles of management:

  1. Avoid the trigger
  2. Dampen down immune response to allergens
• Avoiding the trigger:

  • Nasal irrigation with saline
  • Hay fever - avoid grassy open spaces, keep windows shut in cars, avoid drying clothes outside
  • Dust mites - use synthetic pillows and change regularly, avoid carpets, good ventilation of home
  • Animal - avoid contact, wash surfaces animals in contact with
• Dampening down immune response:

  • Use a combination of following options:
  • Antihistamines- Intranasal (azelastine) or non-sedating oral (cetirizine)
  • Intranasal corticosteroids (e.g. mometasone, fluticasone) - takes up to 2 weeks to see maximal effect
  • Length of treatment depends on exposure to allergen e.g. if hay fever only need treatment during high pollen count
• Options to consider if antihistamines and steroids ineffective:

  • Intranasal decongestants (xylometazoline)
  • Intranasal anticholinergic (ipratropium bromide) - especially good for rhinorrhoea as inhibits mucosal glands
  • Leukotriene receptor antagonist (Montelukast) - mainly if con-existing asthma, blocks effects of leukotrienes released from mast cells
  • Oral corticosteroids (short course) - for severe uncontrolled symptoms
• When to consider secondary care referral:

  • Diagnosis unclear or any red flags e.g. signs of nasal cancer
  • Suspected precipitating cause e.g. deviated septum
  • Troubling symptoms despite conventional therapy - allergy services can offer allergen immunotherapy or biologic therapy e.g. omalizumab - monoclonal antibody against IgE
• Pollen food allergy syndrome:

  • Mostly occurs in patients with allergic rhinitis
  • Type of food allergy when patients react to allergens contained within raw fruit and vegetables - cross reactivity of certain aeroallergens (e.g. birch pollen)
  • Lips, mouth, tongue, throat swelling, itching, tingling (anaphylaxis is rare)
  • Common culprits: apples, apricots, pears, cherries, kiwi, mango, plums, peaches, carrots, celery
  • Cooked food doesn't cause reaction due to proteins changing when heated
• Nasal spray technique:

  • Hold the spray in the left hand when spraying into the right nostril and vice versa
  • Aim to spray slightly outward, away from the nasal septum
  • Do not sniff at the same time as spraying - sends medication straight to back of throat
  • Patients should not taste the spray at the back of the throat