Allergic rhinitis involves inflammation of the mucous membranes of the nose but can involve the eyes, eustachian tube, middle ear, sinuses and pharynx. It is a Type I hypersensitivity reaction (IgE/mast cell mediated) usually against things like pollen (seasonal), dust and animal dander (perennial) and is thought to have genetic aetiology (although environmental factors will likely play a role). It is commonly associated with other atopic disease e.g. asthma and eczema.
- Watery rhinorrhea (eosinophillic), sneezing, nasal obstruction, conjunctival irritation and pruritus
- The turbinates may be swollen and mucosa pale or dark (the paleness is due to oedema while a dark mucosa is due to vasodilation- both can be a sign of allergic rhinitis)
- A ‘classic’ sign in children is a crease just below the angle of the nose caused by rubbing and itching (the ‘allergic salute’)
Skin prick tests are first line, but they may not be suitable in severely affected patients. RAST (radio-allergo-sorbent test) can be used if an allergen is highly suspected (not ideal if there is not a clue what is causing the reaction).
- Avoidance of the allergen is the first line treatment.
- Antihistamine drugs e.g. H1 receptor antagonists like cetirizine/fexofenadine
- Decongestants e.g. pseudoephedrine
- Nasal sprays e.g. sodium chromoglycate (mast cell stabiliser)
- Nasal steroids e.g. beclamethasone
- Topical steroids (rarely used for rhinitis)
- Desensitisation (only works for certain allergens)