Allergic rhinitis is an inflammation of the nasal mucosa (lining epithelium) which is triggered by an allergic reaction. The inflammation is caused by an excessive degranulation of mast cells (one sort of immune cell). When exposed to allergens, the IgE (one kind of immunoglobulin responsible for Immune system) covered mast cells degranulate releasing inflammatory mediators which results in a local inflammatory reaction.

Inciting factors

The triggers responsible for allergic rhinitis may be classified as either seasonal or perennial. Seasonal allergens are for the most part found outdoors. Common seasonal allergens include tree, grass and weed pollens, and airborne molds. As one would suspect, these allergens depend very much on the geographic area. Perennial allergens tend to be found indoors and include among others things, dust mites and animal dander (especially from cats).

Signs and symptoms

People suffering from allergic rhinitis usually complain of itchy eyes, nose and palate, watery rhinorrhea, nasal obstruction, sneezing attacks that are often violent and prolonged, conjunctival irritation and lacrimation. They often have edematous nasal mucosa which is classically pale or violet in colour and excessive clear mucus within

the nose which often contains large numbers of eosinophils. Children may have a nasal skin crease as a result of chronically trying open their nasal airway, the "allergic salute".

Management

The first step In managing a patient with allergic rhinitis is to educate them about the importance of avoiding allergen contact Even the best medical therapies are ineffective in the face of a high allergen load.

• Antihistamines are very effective in acute episodes. Generally, the non-sedative antihistamines are preferred to sedative ones.

•Topical vasoconstrictors Le. decongestants may be added to the antihistamines for temporary relief but their use should be limited to less than 5 days to minimize the risk of developing rebound nasal congestion.

• When antihistamines and decongestants are insufficient or patients require daily medications, topical steroids should be considered. In general, they are very effective. Patients starting topical steroids should be taught that it takes three or four days before they will see any beneficial effects.

• For severe cases, desensitisation therapy has also been shown to be effective.

• Surgery has a role for patients who have either septal deviations or large turbinates and chronic rhinitis.