Allergic rhinitis is a non-infective inflammatory condition of the Nose and Para nasal sinuses. The symptoms usually start after an exposure to a triggering factor (allergen). They can be intermittent or persistent. Some common Allergens are
The common symptoms of rhinitis include:
- Running nose
- Blockage of nose
- Itching and excessive sneezing
- Watering and itching of eyes
- Itching of the throat
The common causes of rhinitis include:
- Pollen of grass, weeds and trees
- House dust mite
- Animal dander
- Air pollutants
The risk factors that can lead to rhinitis include:
- Genetic component: There is an established risk factor between allergic rhinitis and family history of allergy
- Environment: It is more prevalent in developed countries. The prevalence is increasing with urbanization. Many possible factors are lifestyle changes, increased exposure to allergen, pollution, and dietary modifications such as increased junk food causing reduced protective nutrients, stress and even good hygiene.
Allergic rhinitis can predispose a person to develop Asthma, sinusitis, middle ear infections, sleep disorders and lower respiratory tract infections. Allergic rhinitis is a risk factor for development of subsequent asthma and is a frequent cause of exacerbations of asthma.
Allergic rhinitis is diagnosed by a combination of history, examination and lab tests such as:
- Presence of increased eosinophil cells in blood. Eosinophils are a type of white blood cells, which increase in number in patients with allergy.
- Nasal smear is examined for eosinophil cells which are usually increased in patients with allergic rhinitis.
- Skin prick test: In this test, a standardized allergen extract is introduced in to the skin of the forearm and observed for formation of wheal and flare after 15 mins. Reactions greater than 3 mm are regarded positive. Patient should not take any antihistamines 2 days prior to skin prick test. Skin prick tests are simple, cheap and safe. Systemic reactions are very rare. A batch of allergens can be tested in the same sitting.
- Blood tests for allergens include Radio allegro sorbent test (RAST) or by fluorescent assay ELISA.
- Nasal allergen challenge: Allergen is introduced into the nose and any reaction is measured and compared to placebo. This is the gold standard for allergy diagnosis. Nasal challenge test is time consuming, difficult and requires extensive laboratory facilities.
The various conservative measures may include:
Avoidance of allergen: Identifying the allergens and avoiding them is the best method. Major indoor allergens include house dust mite, domestic pets, cockroach and molds. Seasonal rhinitis results from exposure to pollens. Some measures for avoidance are using allergen proof fabric for mattress, pillow covers, hot wash of bedding at 550 C, removing objects that accumulate dust, treating carpets with acaricide, avoiding contact with cats, if not possible, washing them regularly and keeping them out of bedroom. For pollens, using car windows with pollen filters and avoiding grassy open spaces helps.
Pharmacotherapy (drug treatment):
Antihistamines: These rapidly relieve the running nose, itching and sneezing. Some older drugs may cause sedation and learning impairment temporarily. Some commonly used antihistamines are diphenhydramine, ebastine, loratidine, cetrizine, fexofenadine, levocetrizine, desloratidine and azelastine. Some antihistamines may cause cardiac arrhythmias and to be avoided by such patients.
Topical steroids: These are the most effective treatment for allergic rhinitis. Regular treatment is necessary as the onset of action is slow and maximum effect occurs after several days. Nasal steroid reduce inflammation, eye symptoms and improve the sense of smell. They reduce the risk of asthma exacerbations. Side effects are nasal bleeding and minor irritation.
Mast cell stabilizers: They prevent the release of histamine, which is a mediator responsible for allergic symptoms.
Decongestants: Decongestant nasal drops/sprays: They reduce nasal obstruction, but prolonged use can cause a condition called Rhinitis Medicamentosa where there is excessive nasal obstruction and loss of response to the drug. Systemic decongestants reduce nasal obstruction. They have the side effects of sleeplessness and increased blood pressure.
Systemic corticosteroids: For very severe symptoms, oral steroid tablets can be used. Regular use is associated with significant systemic side effects.
Allergen immunotherapy involves repeated administration of an allergen extract in order to induce a state of immunological tolerance. This reduces clinical symptoms and also the requirements for medication during subsequent natural allergen exposure. It is indicated for patients with severe allergic rhinitis who fail to respond adequately to drug therapy. Immunotherapy offers the potential for long-term disease modification and prophylaxis.
Side effects of immunotherap
Local reactions are minimal. Systemic reactions occur in 10% of people, which include symptoms like mild asthma and itching. Rarely severe reactions like anaphylaxis and generalized body itching occur. In view of the systemic side effects, it is done only in specialist centers.
Surgery has a very limited role in treatment of rhinitis. Submucous diathermy and surface cautery of the inferior turbinate bone of the nose are the procedures practiced in some centers to relieve nasal obstruction and discharge.