What is allergic rhinitis?
Allergic rhinitis is a major health problem which affects up to 20% of the general population. It is a condition in which there is inflammation of the inner lining of the nose (‘rhinitis’) which is caused by an allergy. The commonest type of allergy is usually to something that is breathed in. This is because one of the functions of the nose is to filter unwanted particles from the air, and if you are allergic to one of these particles, this will cause inflammation of the lining of the nose to an extent which is out of proportion to the amount of allergen inhaled. In other words, inhaling even a tiny amount of the agent to which you are allergic will cause a significant amount of inflammation.
What are the symptoms of allergic rhinitis?
When inflammation occurs within the nose, this causes a feeling of a blocked nose, sneezing, watery discharge from the nose and itchy eyes. Sometimes the nasal discharge can become thicker and more mucous-like, particularly if there is continued exposure to the allergen or if the sinuses become involved. In addition, some people experience wheezing and shortness of breath, which occurs when the allergen affects the lungs. This can happen in anyone, not only those with asthma. In fact, even if you do not currently have asthma, the risk of developing asthma if you already have allergic rhinitis is 3 times greater than for the general population.
What are the commonest allergens that cause allergic rhinitis?
The commonest air borne allergens that cause allergic rhinitis include pollens, of which grass and various tree varieties are the most prominent, house dust mite, cat and dog, feathers and various types of airborne fungi such as aspergillus or cladosporum (this is the black mould often seen in moist environments such as bathrooms). Other substances can also cause allergic rhinitis, including dairy products, alcohol, seafood and nuts.
How do I find out if I am allergic to something?
Most people usually have some idea whether they are allergic to something based on the history of a reaction on exposure to a particular substance. If you have your suspicions, you could try to avoid the item to which you think you are allergic and see whether your symptoms decrease with time.
There are tests which can be performed to confirm whether you are allergic to something. These involve either a skin prick allergy test or a blood test. Skin prick allergy tests involve placing a small amount of several common allergens onto the forearm and observing whether there is a reaction of the skin. Some hospitals or clinics do not recommend such a test in children or pregnant women, and in such cases a blood test can be performed, which looks for the reaction of the immune system on exposure to a range of different agents.
What is the treatment for allergic rhinitis?
The mainstay of treatment involves allergy avoidance. This is often more difficult than it sounds as for this strategy to be effective, it is necessary to completely avoid all possible exposure to the allergen. It is not sufficient to merely reduce exposure to it as a reaction can be triggered with even the tiniest of exposures. Avoiding all instances of possible exposure may simply not be practical or possible. For example, a gardener unfortunate enough to have an allergy to tree pollen may never be able to avoid this allergen.
In terms of medical therapies, antihistamines are widely used for allergic rhinitis as they reduce symptoms of itching, sneezing and watery nasal discharge. Intranasal steroid sprays are also extremely effective as they diminish the inflammation of the lining of the nose, thereby relieving the feeling of nasal blockage. Sometimes, nasal decongestants need to be used for short term symptom relief. Salt water douches can also be helpful by clearing mucus from the nose and eliminating irritants and allergens from the nasal cavity, thereby allowing nasal steroid sprays to work more effectively.
Is there a role for surgery in allergic rhinitis?
Most people with allergic rhinitis are successfully managed with allergy avoidance and medical therapies. However there are certain situations in which surgery may have a role.
Indications for surgery in allergic rhinitis:
- Persistent symptoms resistant to medical treatment
- Anatomically large, swollen intranasal tissue (inferior turbinates)
Surgery in general involves resection or reduction of the inferior turbinates, which are structures within the nose which swell up in response to allergy or infection. Excessive and persistent exposure to an allergen can result in swelling to such a degree that causes a permanent enlargement of these turbinates. This results in nasal block which cannot always be reversed by medications alone.
- Resection: Total resection restores the intranasal airway but can be associated with problems with crusting and bleeding because of destruction of the highly specialised mucosal lining
- Reduction: This involves reduction of the mucosal surface only. Improvement in the nasal airway does occur but the benefits are generally short-lived and the procedure often needs to be repeated. Diathermy is the most commonly adopted technique
- Turbinoplasty: In this procedure, the outer part of the inferior turbinate is removed, leaving the inner mucosal lining intact which is crucial in restoring normal nasal physiology.
Advantages of the turbinoplasty technique include considerably less intra-operative bleeding, reduced likelihood of long-term crusting owing to preservation of the mucosa, and persistence of benefits in the long-term. This lower morbidity operation therefore offers the same advantages of both of the above alternative procedures without the associated disadvantages.
What are the other conditions that can be associated with allergic rhinitis?
Allergic rhinitis occurs as part of an immune system-mediated hypersensitivity reaction to a particular substance or allergen. There are other conditions that can occur in the body which are also caused by a similar hypersensitivity of the immune system to certain agents. For example, eczema is a condition of extreme sensitivity of the skin to certain topically applied substances. This results in itching, dryness and redness of the skin in a manner analogous to that of allergic rhinitis.
Asthma is a condition of the lower airways and lungs which is caused, as part of its underlying pathophysiology, by a hypersensitivity of the airways to certain triggers such as pollens, exposure to cold or smoke, or exercise. It is well established that patients with allergic rhinitis are 3 times more likely to develop asthma at some stage in their lives. Furthermore, patients with both asthma and allergic rhinitis find that their asthma symptoms are more severe and require more medications than in patients with asthma alone. What is interesting is that in patients with both conditions, treatment of the allergic rhinitis alone with topical intranasal steroid sprays results in a reduction in their asthma symptoms and a decrease in the amount of medications they need to take for their asthma. Given that asthma can be a life threatening condition, taking a nasal spray is a simple and potentially significant intervention.