|
 |
|
|
|
|
|
nasal allergies Alternative Names
allergic rhinitis, allergic rhinosinusitis, hayfever
Definition
Nasal allergies are caused by the interaction of allergens with allergy cells within the lining of the nose.
What is going on in the body?
The nose has numerous important functions. It is an excellent humidifier and warmer of air destined for the lungs. The lining inside the nose contains important components of the body's immune system. One part of the immune system is involved in immediate hypersensitivity reactions, which result in allergies.
The presence of allergies within an individual is largely genetically determined. In a susceptible person, allergens that enter the nose (such as pollens, dust, dust mites, mould spores, and animal dander) interact with IgE antibody that is attached to the mast cells inside the lining of the nose. When an allergen binds to the IgE on the mast cell, this causes discharge of a variety of compounds, such as histamine. Histamine causes a variety of symptoms, such as sneezing, nasal congestion, and nasal discharge.
The mast cells also release a number of other inflammatory substances which pull another group of cells, called eosinophils, into the nasal lining. The eosinophils travel out of the blood vessels into the lining of the nose over a 6 to 24-hour period. Once eosinophils arrive in the inflamed tissue, they release substances that can create additional symptoms hours after the original exposure. The initial reaction in response to exposure to the allergen is called the early reaction. The burst of symptoms occurring hours after the initial exposure is called the late phase reaction.
For example, an individual who is sensitive to cats will develop an immediate allergic reaction, due to the release of mast cells, when exposed to a cat. Symptoms of the immediate reaction include sneezing, eye itching, eye watering, itching in the nose and ears, nasal stuffiness, and drainage. This initial acute attack may continue as long as the individual is exposed. Once the person leaves the environment, then the allergy symptoms subside. However, once the individual is away from the cat, the release of eosinophils may bring on another wave of the same type of allergic symptoms.
Eosinophils are also responsible for the "priming" effect in which the same daily amount of allergen causes a gradual worsening of symptoms. The priming effect also causes a heightened sensitivity to other triggers that would not normally cause allergic reactions in the person. Eosinophils also make the tissues more sensitive to non-allergic stimuli, such as dry air and perfume.
What are the signs and symptoms of the condition?
The symptoms of a nasal allergy are: - sneezing
- nasal stuffiness with subsequent difficulty breathing
- clear, watery nasal discharge
- nasal itching
- deep itching within the ear
- coughing, and itching, watering and redness of the eyes.
Late phase reactions are very similar. The individual who has chronic allergy exposure may start to see other symptoms, such as: - more constant nasal stuffiness
- a thicker, clear to white mucous secretion
- reduced sense of smell
- sinus headaches, usually in the forehead, cheek, and between the eyes
An individual with chronic allergies may also start to be affected by non-allergic stimuli, such as dry air, cold air, smoke, and particles within the air.
What are the causes and risks of the condition?
The main cause of nasal allergies is an interaction between cells lining the nose and allergens such as pollens, dust, dust mites, moulds, and animal dander.
Nasal allergies can predispose an individual to sinus infections and asthma. Billions of dollars per year of lost productivity occur because of allergic disease.
What can be done to prevent the condition?
Many allergens are present in the air, so it may be very difficult for some people to prevent nasal allergies. - If a person's allergies are triggered by cats or specific animals, it is important to keep the animals out of the home.
- People who suffer from dust or dust mite allergies can benefit from having wood floors, air-tight pillow and mattress covers. Persons with severe nasal allergies may consider moving to a drier climate.
- People with nasal allergies should avoid tobacco smoke.
One of the principles in allergic disease management is avoiding triggers. Antihistamines, such as diphenhydramine or chlorpheniramine, do not prevent the disease but only block the symptoms. Nasal steroid sprays, such as rhinocort, help to stop mast cells from releasing their substances but still do not prevent the allergen IgE interaction. Nasal steroids also do not stop the allergen from binding to mast cell IgE, but do stop the mast cell from discharging and thus prevent early symptoms.
How is the condition diagnosed?
A careful history and physical examination is important in diagnosing nasal allergies. The eyes may be bloodshot, and the nasal linings are often swollen with excessive amounts of clear nasal discharge. The person may report symptoms after a specific exposure, such as being around cats. Sometimes, the individual will have symptoms during particular seasons. For those with ongoing symptoms such as nasal stuffiness, thick, clear nasal discharge, loss of smell, and chronic sinusitis, other tests can be performed. The doctor may order a test that looks for eosinophils in the nasal mucous. Allergy testing may be done to determine the particular triggers that cause the individual's symptoms.
What are the long-term effects of the condition?
For the person who suffers from brief seasonal allergies, there are very few long-term effects. Most of the long-term effects occur in those who have prolonged or frequent periods of allergic disease. The presence of allergic rhinitis increases the risk of asthma 4 times. Chronic allergies, such as those seen with dust or dust mites and moulds, are more likely to develop chronic long-term symptoms. Individuals with long- stretches of allergic disease, such as spring through fall, may also develop long term symptoms. These long-term symptoms include: - constant nasal congestion
- excessive, thick nasal mucous
- sinus headaches
- facial discomfort
- loss of sense of smell
- chronic cough
- fatigue
- snoring, in persons with chronic nasal congestion
Tissue damage and inflammation induced by eosinophils during late phase reactions are largely responsible for the chronic symptoms.
What are the treatments for the condition?
The mainstay of allergy treatment is avoiding what an individual is allergic to. This is practical for those who have pet, dust, or dust mite allergies but is less practical for those who are sensitive to pollens and moulds. For short-term allergic disease, oral antihistamines, such as diphenhydramine, loratadine and fexofenadine, are very effective in controlling the symptoms of sneezing, eye watering and itching, nose and ear itching, and nasal discharge. Antihistamines generally do a poor job in diminishing nasal stuffiness. Therefore, it is common to add a decongestant, such as pseudoephedirne, to an antihistamine preparation. For severe, acute flare-ups, oral steroids, such as prednisone, are very useful because they block the allergic response.
For those with more prolonged allergic disease, the mainstay of management involves the use of nasal steroid sprays, such as beclomethasone and mometasone. These agents have been around for about 20 years and, unlike chronic oral steroid use, nasal steroid spays have an excellent safety profile. Compared to oral antihistamines, they control acute symptoms more effectively and also block the late phase reaction in which most of the chronic tissue damage occurs. When an individual is on chronic nasal steroids to control their allergies, oral antihistamines can still be used if the patient has allergic symptoms that develop while on topical steroid sprays.
Using environmental controls, such as air filters and maintaining a clean environment, are useful. Other treatments may be helpful, such as salt water nasal sprays and mucous thinners which can help clear excessively thick nasal secretion. For the patient who has chronic or prolonged periods of allergic disease or who is having complications from their allergies, such as sinus infections or asthma, or who is not responding well to medications, desensitising for allergens by injections or drops under the tongue has become an important tool in the management.
What are the side effects of the treatments?
Many of the over-the-counter antihistamines cause drowsiness and decreased mental alertness. Individuals on these antihistamines will often be excessively tired and studies have clearly shown a decrease in mental function and impaired task performance.
There is considerably less risk of drowsiness and decreased mental alertness with some of the newer antihistamines on the market. These have become the preferred agents of choice for oral antihistamine usage. Such medications include loratadine, certirizine, and fexofenadine. Side effects with commonly used decongestants, such as pseudoephedrine, include elevation of blood pressure, fast heart rate, anxiousness, and difficulty sleeping.
Very few side effects occur with the use of saline sprays. The main side effects with the use of nasal steroids include nosebleeds, nasal crusting, and possibly a perforation, which is a hole that develops in the septum. The septum is a bone and cartilage wall that divides the nose into the two separate sides.
There are a few acute side effects from oral steroids, such as increased appetite, irritability, excitability, sleeplessness, weight gain, and stomach irritation. Chronic steroid usage can cause loss of muscle mass, loss of bone mass, predisposition to infection, diabetes, poor wound healing, and cataracts. Side effects to desensitising Injections could include a severe allergic reaction or anaphylaxis, which is life threatening, an asthma attack, or a drop in cardiopulmonary function.
What happens after treatment for the condition?
With successful treatment of allergies, symptoms should improve.
How is the condition monitored?
Monitoring the disease is mostly based on symptom control.
Author: Bill Harrison, MD
Reviewer: HealthAnswers Australia Medical Review Panel
Editor: Dr David Taylor, Chief Medical Officer HealthAnswers Australia
Last Updated: 1/10/2001
Contributors
Potential conflict of interest information for reviewers available on request |
|
|
| |
|
|
|
|
|
|
|
|
