Allergic rhinitis

Description

Allergic rhinitis is an allergic inflammation of the nasal airways. The term rhinitis is a derivative of rhino, meaning nose and is translated as “irritation of the nose”. Allergic rhinitis is an allergic reaction to small particles of plant or animal protein that weigh so little that they’re carried through the air and get deposited on the membranes of the eyes, nose and throat. Unlike a cold, allergic rhinitis is not caused by a virus and the time of year a person is affected depends on which allergens an individual is allergic to. It usually affects about one in five people, more frequently during spring and summer when more pollen (small light dry protein particles) or fungal spores are in the air.

Allergic nasal disorders are divided into two main types namely perennial (occurs throughout the year) and seasonal (occurs during specific seasons) allergic rhinitis. Perennial allergic rhinitis is mainly caused by animals, moulds and house dust mite.

Seasonal allergic rhinitis does not usually develop until after six years of age while perennial allergic rhinitis is commonly seen in younger children. Allergic rhinitis generally develops during childhood or early adulthood with the symptoms becoming less severe as the individual ages.

Symptoms

Sensitisation is a process where an individual’s immune system mistakenly identifies a harmless airborne substance as dangerous and start producing antibodies to this substance. Allergic reactions result from the release of powerful chemical agents, such as an antibody called immunoglobulin E, which attack the particles and then release the chemical histamine that causes the symptoms of allergic rhinitis. Symptoms include severe bouts of sneezing (usually more acute during the morning), intense itching of the nose, palate and even the ear canals, watery nasal mucus, itchy and watery eyes which are sensitive to light, stuffy nose, frequent throat clearing, snoring, repeated nosebleeds and headaches. Symptoms appear immediately after an individual has been exposed to an allergen.

Symptoms associated with a chronic cold such as sneezing, runny nose, congestion and sinus pressures are synonymous with allergic rhinitis.

Causes

Plants commonly associated with allergic rhinitis include trees (pine, birch, cedar, hazel, horse chestnut, willow and olive trees), grasses (ryegrass) and weeds (ragweed and nettle). Fungal spores are occasionally indicated during warm weather months. Early springtime hay fever is usually caused by pollens from trees while late springtime pollens are produced by grasses. Autumnal hay fever is triggered by weed pollen. Garden plants are mostly pollinated by insects; their pollen is too heavy to be airborne and thus have no implication for hay fever.

Usually pollen levels are highest during mid morning and larger amounts of pollen are present on hot windy days. Especially after thunderstorms when the weather is hot and humid and pollen grains rupture, releasing fine starch granules which are highly allergic and can penetrate deep into the lungs.

Testing for rhinitis

The ideal way to manage an allergy is to avoid the substances that cause allergic reaction. It is therefore very important to first identify these substances (allergens), using skin tests, blood tests and eye tests. The most common method of allergy testing is a skin test which includes intradermal, scratch or patch testing.

Treatment

Avoiding the trigger substance may be the best way to control most allergies yet it is difficult to avoid pollen or spores as they are not visible to the eye and are airborne.

Most products available for treating allergic rhinitis are available at pharmacies without a prescription. Medications such as antihistamines combat the symptoms caused by the production of histamines in reaction to an allergy. Antihistamines help with itching, sneezing and runny nose by blocking the histamine, the symptom-causing chemical released by an individual’s body during an allergic reaction.

Allergy symptoms are further controlled by decongestants, which shrink the swollen membranes in the nose, resulting in easier breathing. Decongestants can cause a number of side-effects, including increased blood pressure, irritability, insomnia and headache. It is not advisable to use a decongestant nasal spray for more than three days as it can actually worsen symptoms when used continuously.

Some individuals with allergies may need specialised prescription medications such as corticosteroids, cromolyn sodium and ipratropium nasal sprays. Cortisone is effective in reducing the inflammation which causes swelling, sneezing and a runny nose. Should antihistamines and cortisone prove ineffective, allergy desensitisation or immunotherapy may be needed. Desensitisation is a process where increasing amounts of a known allergen, such as grass pollen extract, is injected beneath the skin at weekly intervals initially and then every six weeks for a period of three years in order for the immune system to become tolerant of the allergen and seize to react. Desensitisation is used when only one allergen is found to be the culprit in an allergic rhinitis attack. The aim is to encourage the immune system adversely when exposure to the specific allergen occurs.

Immunotherapy entails a five year injection strategy where tiny amounts of allergens are injected regularly in order to accustom the body to these allergens and decrease the need for medications.

Rinsing a person’s nasal passage with salty water is a quick, very effective and inexpensive way to relieve nasal congestion as rinsing directly flushes out mucus and allergens from the nose.

If left untreated, a person suffering from allergic rhinitis runs the risk of developing more serious allergic conditions such as eczema or asthma.

Prevention

Practical and effective preventative measures include closing doors and windows during the pollen season, not hanging laundry outside as pollen can stick to sheets and towels, using air conditioning and an allergy-grade ventilation system, avoiding outdoor activity in the early morning as pollen counts are highest at this time and staying indoors on dry, windy days. Using allergy-proof covers on mattresses and pillows and washing sheets and blankets in water heated to at least 54degrees Celsius as well as vacuum cleaning carpets weekly with a vacuum cleaner equipped with a small-particle or HEPA filter will diminish the presence of dust mites in your home. If you know that you will be exposed to hay fever triggers, it is advisable to take medication before symptoms starts, provided that your doctor recommends this.

 

Sources
http://www.health24.com/medical/Condition_centres/777-792-797-1546,14125.asp
http://www.medicalnewstoday.com/articles/160665.php
http://www.medicinenet.com/hay_fever/article.htm
http://www.mayoclinic.com/health/hay-fever
http://www.nhs.uk/Conditions/Hay-fever/Pages/Introduction.aspx
http://en.wikipedia.org/wiki/Allergic_rhinitis