Hay fever or seasonal allergic rhinitis is a common allergic disorder characterised by inflammation of the nasal passages.
In susceptible individuals, exposure to an allergen causes the release of histamine and other inflammatory mediators. The inflammatory cells then migrate to the nasal mucosa, increasing its sensitivity to further exposure to allergens and to non-specific stimuli.
Hay fever often starts in the mid-teens. It is associated with asthma and eczema, and a personal or family history of atopy.
The main symptoms include nasal blockage. This is usually intermittent and affects each nostril alternately. Permanent unilateral blockage suggests an anatomical problem. Sneezing may be paradoxical.
Rhinorrhoea is clear and anterior or posterior. Purulent rhinorrhoea suggests infection or a foreign body and clear unilateral rhinorrhoea may suggest a cerebrospinal fluid leak.
Eye itching, redness, watering or lid swelling may occur if there is concomitant allergic conjunctivitis. There can be diminished senses of smell or taste, headaches, and frequent middle-ear infections. Nasal examination may be normal or show congested mucosa.
Blood eosinophilia and raised serum IgE levels will help confirm the presence of atopy. Skin prick tests may help identify specific allergens. Radioallergoabsorbent blood tests are helpful but expensive.
Patient should be advised to avoid environmental allergen exposure if practical, closing windows and staying indoors on days with predicted high pollen counts, or when the grass is being mown nearby. Air conditioning can help, as does keeping room humidity high.
Medical treatment should start early in the year, for example in March/April, before the seasonal allergen load rises and should be taken continuously throughout the season.
It includes oral or topical antihistamines alone or with cortico-steroids. Preventive medication should be promoted in all but the most intermittent or mild cases.
Second-generation oral antihistamines are effective and long-lasting but can take a few days to achieve maximum effectiveness. Reserve the more expensive third-generation antihistamines for patients who cannot tolerate or do not respond to other antihistamines. Inhaled antihistamines have a shorter onset of action.
Inhaled corticosteroids can be used first line as an alternative to oral antihistamines in mild hay fever, or in combination with them in more severe disease. Inhaled corticosteroids do not affect growth and development in children, but they can cause drying or even bleeding from the nose.
Oral steroids can be used in doses of 1-2mg/kg in children and 30-40mg/day in adults for a few days when rapid control of severe symptoms is desired. Depot IM injections of corticosteroid are no longer used.
Inhaled cromogens are less effective, although they may be used if a patient cannot tolerate inhaled corticosteroids.
Intranasal decongestants can help other topical therapies penetrate the nasal mucosa; but long-term use causes tachyphylaxis. Systemic decongestants tend to be weakly effective.
Oral leukotriene modifiers may be tried in refractive cases in addition to first-line therapies. The effectiveness will usually be apparent within a few days.
Allergen immunotherapy is not recommended in patients with severe hay fever.
Surgical submucous diathermy may help in medically refractive cases.
REFERENCES AND FURTHER INFORMATION
- Van-Cauwenburge P, Bachert C, Passalacqua G et al. Consensus statement on the treatment of allergic rhinitis. European Academy of Allergology and Clinical Immunology. Allergy 2000;55:116-34
- Scadding G K, Richards D H, Price M J. Patient and physician perspectives on the impact and management of perennial and seasonal rhinitis. Clin Otolaryngol Allied Sciences 2000;25:551-7.