It is well-known that people in certain parts of the planet are far more likely to suffer from allergic rhinitis than in other parts, though it is not so clear why that happens. In Denmark, just over one in every 100 visits to a family physician involves seasonal allergic rhinitis, though in Britain the figure is one in 50 and in Australia almost one in 10. The disease is more of an urban than a rural phenomenon, a fact which has led many researchers to point a finger at air pollution as an aggravating condition.
Air pollution may indeed play a role in the increased incidence of this condition, perhaps because gases such as ozone and nitrous oxide are harming epithelial cells, the bloodless surface covering of human tissues, glands, and organs. But one study suggested that the role of air pollution may have been exaggerated. The children of Leipzig, despite breathing the notoriously polluted and sulfur dioxide-laden air of former East Germany, were found to have lower rates of rhinitis than children in the western, alpine city of Munich.
Physicians and rhinologists have traditionally divided allergic patients into those whose symptoms were seasonal and those who suffered all year round. Yet a single patient with a number of seasonal reactions to allergens that peak at different times of year may appear to have a year-round allergy. In any case, an individual with severe perennial symptoms should receive different drug treatments from an individual with mild seasonal symptoms.
For the person who suffers moderate, occasional allergic rhinitis symptoms, there are a variety of pharmacological allies available. Allergen avoidance is, as always, the ideal solution, but it may prove practically impossible for allergy sufferers who have no choice but to share the air they breathe with allergenic pollen. It helps, however, to know when the pollen count of a particular allergenic plant is going to begin climbing, and when it will peak, in order to begin therapy beforehand.
Treatment may include the use of non-sedating oral antihistamines, or topical antihistamines or so-called mast cell stabilizers to the nose and eyes. Mast cells act as receptors for the allergenic pollen, and for the antibody immunoglobulin E which the body uses to defend itself. Its reaction to these signals is to release substances such as histamine that worsen rhinitis symptoms.
Oral antihistamines, which are used to prevent this histamine reaction, offer a number of alternatives in terms of speed of onset and duration of effect for the treatment of milder seasonal rhinitis, available under names such as terfenadine, cetirizine (Zyrtec), astemizole (Hismanal) and acrivastine (Semprex). Topical antihistamines such as levocabastine (Livostin) and azelastine (Astelin), however, are becoming more widely used because their effect can be concentrated on the most affected organ. Topical sodium cromoglycate, long used in treatment of allergic rhinitis symptoms, still has a place today because the absence of significant side effects permits regular use without worry.
Those who suffer from more severe forms of seasonal allergic rhinitis should be treated according to whether they are primarily eye sufferers or primarily nose sufferers. If their symptoms are mostly in the nose, they should receive topical nasal steroids before the beginning of the pollen season to minimize early damage to cells and inflammation, which would release aggravating substances such as histamines and tryptase. Eye treatment may also be necessary for mostly nasal sufferers.
If the eye is the source of most discomfort, choices are limited to the topical use of sodium cromoglycate in conjunction with nasal steroids to lessen general irritation. The only readily-available alternative to that is an oral antihistamine.
Should allergic rhinitis be really severe and treatment beyond the limits of such drugs, the patient will probably need to see a specialist who may, in a crisis, recommend short-term systemic corticosteroids. Immunotherapy may also be considered at this juncture. These more drastic treatments represent the weapons of last resort against seasonal allergic rhinitis at present, but with allergic mechanisms better understood every year, it may not be that way for long.