The most important part of patient treatment for allergic rhinitis is continuous education, about medication, side effects, and allergen avoidance. Avoidance is often difficult or impractical, but it is not as complicated as it sounds. In some cases of pet allergy it is as simple as removing the pet, or if that’s not an option, limiting the animal to one part of the house and removing all carpets and soft furnishings from the area, since animal allergens can remain airborne for hours and can adhere to fabric and other surfaces.
In other kinds of perennial rhinitis, such as dust mite allergy (the most common worldwide), keeping a clean house and reducing carpeting and soft furnishings, particularly in the bedroom, is the key to environmental control. Acaricides, which kill mites, and mite-proof covers are also available. Reducing humidity and ensuring good ventilation also helps. In rhinitis associated with industrial by-products or in rare cases of food-allergic rhinitis, environmental control is simpler: stay away from the allergen.
Such remedies are easier said than done when dealing with seasonal allergens such as pollens and mould spores. Yet even these fluctuate greatly from time to time and from place to place. Being aware of when to avoid the outdoors and installing high efficiency air filters in cars can greatly reduce exposure.
Medication
Four types of drugs are widely used to treat allergic rhinitis: antihistamines, decongestants, mast cell stabilizers and corticosteroids. Antihistamines are antagonists of the body’s own histamine that are directed at target cells in the respiratory mucosa. Because traditional antihistamines were rapidly absorbed into the central nervous system, they caused drowsiness in 10% to 20% of users. Newer antihistamines no longer sedate patients and have few or no side effects. They include terfenadine, astemizole, cetirizine, loratadine and acrivastine. Of these, cetirizine is the only one that is not metabolized at all in the liver and is eliminated from the body intact, while astemizole is distinguished by its slowness of onset and long duration (a half-life of up to 19 days) which make it ideal for maintenance treatments rather than as-needed relief. Recent research has linked some of the new antihistamines, such as terfenadine and astemizole, with cardiac arrhythmia, and they should not be used in conjunction with certain kinds of antibiotics or oral antifungal agents, nor in the presence of liver disease.
Decongestants act by constricting blood vessels in the nose, which block airways when they become engorged by allergic reaction. They function equally well in all kinds of nasal congestion, allergic or nonallergic, but have no effect on the underlying process of rhinitis. They do not replace more fundamental treatments, but rather supplement them. There are topical decongestants that come as sprays or nasal drops, such as oxymetazoline, xylometazoline and naphazoline, and there are oral decongestants such as ephedrine and phenylpropanolamine. The topicals are preferable since they are less prone to systemic side effects such as restlessness, agitation, sleep disturbance, tachycardia and headaches. They are frequently used with antihistamines and often improve results significantly.
Mast-cell stabilizers such as sodium cromoglycate and nedocromil sodium are anti-inflammatory drugs, which are effective in mild to moderate cases of rhinitis, but less so in the most severe cases. These drugs must be used frequently (four to six times daily) to reduce symptoms, and work better against rhinorrhoea and sneezing than against stuffed-up noses, but they are harmless and therefore a useful alternative, particularly for children. Cromoglycate is a useful eyedrop that relieves itchy eyes, a major source of discomfort for rhinitis sufferers.
Corticosteroids are the most potent and also the most problematic of the rhinitis drugs available today. They can be taken locally, orally or through injection, and reduce mast cells close to the epithelial surface of tissue. They reduce rhinitis symptoms through a variety of complex mechanisms that are not clearly understood. Because they inhibit the inflammatory response right where it begins, at the cellular level, they reduce every allergic symptom, though the onset of action is slow.
Intranasal steroids rarely cause systemic side effects when used at recommended dosages, and provide excellent relief in over 90% of patients. One limitation of steroids, the failure to fully relieve eye symptoms, can be remedied by the application of antihistamines. Currently available topical corticosteroids include beclomethasone dipropionate, flunisolide, and budenoside, among others. Beginning a course of steroids before pollen season can prevent cell changes in the nose associated with rhinitis, and after two weeks of use, doses can often be reduced to one a day. The aim should be to use the minimum effective dose for each patient. Though side effects such as nasal irritation in the first few days occur in a minority of patients, topical steroids are relatively harmless.
Systemic steroids are a different matter. They should be used only in very severe cases of rhinitis and then with caution. A short course of an oral corticosteroid such as prednisolone may be considered necessary while waiting for intranasal steroids to take effect. Injections of corticosteroids, sometimes given to hay fever sufferers, are particularly efficient at reducing nasal blockage, but they suppress normal adrenal cortex function for long periods and can have other severe side effects.
Immunotherapy
An expensive, time-consuming and risky procedure which seeks to boost the presence of the immunoglobulins G1 and G4, which appear to reduce allergic reactions, though they do not by any means make symptoms disappear. Since the procedure requires that the patient be exposed to allergen extracts administered orally, nasally or directly under the tongue, grave systemic reactions are a possibility and immunotherapy should never be attempted without resuscitation facilities. It has proved useful in treating birch, grass, ragweed, dog and cat allergies, but is useless against dust mite allergy and not particularly good for hay fever. This form of treatment is altogether too drastic for most rhinitis sufferers, and is rarely used except to treat rhinitis patients with asthmatic symptoms.
Surgery
Occasionally, abnormalities in the nose or sinuses aggravate symptoms of allergic rhinitis, and in these cases, medication may be combined with surgery. Sinus surgery is sometimes used to correct secondary symptoms caused by sinus obstruction. The operation is usually followed by a course of topical corticosteroids.