By Dr Unnikrishnan N
Allergic rhinitis is a common disorder that is strongly linked to asthma and conjunctivitis. It is usually a long-standing condition that often goes undetected in the primary-care setting. The classic symptoms of the disorder are nasal congestion, nasal itch, rhinorrhea and sneezing.
Rhinitis is broadly defined as inflammation of the nasal mucosa. It is a common disorder that affects up to 40% of the population. Allergic rhinitis is the most common type of chronic rhinitis, affecting 10 to 20% of the population, and evidence suggests that the prevalence of the disorder is increasing. Severe allergic rhinitis has been associated with significant impairments in quality of life, sleep and work performance.
In the past, allergic rhinitis was considered to be a disorder localised to the nose and nasal passages, but current evidence indicates that it may represent a component of systemic airway disease involving the entire respiratory tract. Evidence has shown that allergen provocation of the upper airways not only leads to a local inflammatory response, but also to inflammatory processes in the lower airways, and this is supported by the fact that rhinitis and asthma frequently coexist.
Pathphysiology
In allergic rhinitis numerous inflammatory cells, infiltrate the nasal lining upon exposure to an inciting allergen (most commonly airborne dust mite fecal particles, cockroach residues, animal dander, moulds, and pollens). This triggers the release of mediators, such as histamine and leukotrienes, that are responsible for itching, rhinorrhea (runny nose), mucous secretion etc.
Classification
Rhinitis is classified into one of the following categories according to etiology: IgE-mediated (allergic), autonomic, infectious and idiopathic (unknown).
Traditionally, allergic rhinitis has been categorised as seasonal (occurs during a specific season) or perennial (occurs throughout the year). However, not all patients fit into this classification scheme. For example, some allergic triggers, such as pollen, may be seasonal in cooler climates, but perennial in warmer climates, and patients with multiple “seasonal” allergies may have symptoms throughout most of the year.
Therefore, allergic rhinitis is now classified according to symptom duration (intermittent or persistent) and severity (mild, moderate or severe). Rhinitis is considered intermittent when the total duration of the episode of inflammation is less than six weeks, and persistent when symptoms continue throughout the year.
Symptoms are classified as mild when patients are generally able to sleep normally and perform normal activities (including work or school); mild symptoms are usually intermittent. Symptoms are categorised as moderate/severe if they significantly affect sleep and activities of daily living and/or if they are considered bothersome.
Diagnosis and investigations
Allergic rhinitis is usually a long-standing condition. Patients suffering from the disorder often fail to recognise the impact of the disorder on quality of life and functioning and, therefore, do not frequently seek medical attention. Studies have shown that rhinitis is present in up to 95% of patients with asthma.
Symptoms of allergic rhinitis
The most common symptoms of this condition include:
l Sneezing
l Runny nose
l Stuffy nose
l Itchy nose
l Coughing
l Sore throat
l Itchy and watery eyes
l Dark under-eye circles
l Frequent headaches
l Eczema-type symptoms (extremely dry, itchy skin that often blisters)
l Hives (red, sometimes itchy, bumps on the skin)
l Excessive fatigue
Diagnostic tests
Diagnostic testing is usually necessary to confirm that underlying allergies cause the rhinitis. Skin-prick testing is considered the primary method for identifying specific allergic triggers of rhinitis. Skin prick testing involves placing a drop of a commercial extract of a specific allergen on the skin of the forearms or back, then pricking the skin through the drop to introduce the extract into the epidermis. Within 15-20 minutes, a wheal-and-flare response (an irregular blanched wheal surrounded by an area of redness) will occur if the test is positive. Testing is typically performed using the allergens relevant to the patient’s environment (eg, pollen, animal dander, moulds and house dust mites). A reasonable alternative to skin prick testing is the use of allergen-specific IgE tests that provide an in vitro measure of a patient’s specific IgE levels against particular allergens.
Treatment
The treatment goal for allergic rhinitis is relief of symptoms. Therapeutic options available to achieve this goal include avoidance measures, oral antihistamines, intranasal corticosteroids, leukotriene receptor antagonists, and allergen immunotherapy. Other therapies that may be useful in select patients include decongestants and oral corticosteroids. As mentioned earlier, allergic rhinitis and asthma appear to represent a combined airway inflammatory disease and, therefore, treatment of asthma is also an important consideration in patients with allergic rhinitis.
Allergen avoidance
The first-line treatment of allergic rhinitis involves the avoidance of relevant allergens (eg. house dust mites, moulds, pets, pollens) and irritants (eg. tobacco smoke). Patients allergic to house dust mites should be instructed to use allergen-impermeable covers for bedding and to keep the relative humidity in the home below 50% (to inhibit mite growth).
Pollen exposure can be reduced by keeping windows closed, using an air conditioner, and limiting the amount of time spent outdoors during peak pollen seasons. For patients allergic to animal dander, removal of the animal from the home is recommended and usually results in a significant reduction in symptoms within 4-6 months. Use of high-efficiency particulate air (HEPA) filters and restricting the animal from the bedroom or to the outdoors may be needed to attempt to decrease allergen levels.
Other therapeutic options
Oral and intranasal decongestants (eg, pseudoephedrine, phenylephrine) are useful for relieving nasal congestion in patients with allergic rhinitis. Furthermore, these agents are contraindicated in patients with uncontrolled hypertension and severe coronary artery disease. Prolonged use of intranasal decongestants carries the risk of rhinitis medicamentosa (rebound nasal congestion) and, therefore, these agents should not be used for more than 5 to 10 days.
Although not as effective as intranasal corticosteroids, sodium cromoglycate (Cromolyn) has been shown to reduce sneezing, rhinorrhea and nasal itching and is, therefore, a reasonable therapeutic option for some patients. The anti-IgE antibody omalizumab has also been shown to be effective in seasonal allergic rhinitis and asthma.
Surgical therapy may be helpful for select patients with rhinitis, polyposis, or chronic sinus disease that is refractory to medical treatment. Most surgical interventions can be performed under local anaesthesia in an office or outpatient setting.
It is important to note that allergic rhinitis may worsen during pregnancy and, as a result, may necessitate pharmacologic treatment. The first-generation antihistamines may be considered for allergic rhinitis in pregnancy and, if required, chlorpheniramine and diphenhydramine should be recommended given their longer-term safety record.
If an intranasal corticosteroid is required during pregnancy, beclomethasone or budesonide nasal spray should be considered as first-line therapy because of its longer safety record.
Allergic rhinitis is a common disorder that can significantly impact quality of life. The therapeutic options available for the treatment of allergic rhinitis are effective in managing symptoms and are generally safe and well-tolerated.
Second-generation oral antihistamines and intranasal corticosteroids are the mainstay of treatment for the disorder. Allergen immunotherapy as well as other medications such as decongestants and oral corticosteroids may be useful in select cases.
Key take-home messages
Allergic rhinitis is linked strongly with asthma and conjunctivitis.
Allergen skin testing is the best diagnostic test to confirm allergic rhinitis.
Intranasal corticosteroids are the mainstay of treatment for most patients that present to physicians with allergic rhinitis.
Allergen immunotherapy is an effective immune-modulating treatment that should be recommended if pharmacologic therapy for allergic rhinitis is not effective or is not tolerated.
- Dr Unnikrishnan N is a Specialist- ENT at Aster Medical Centre, Old Al Ghanim
