Medical Matters: School exams started on Wednesday; by now students are settled into a daily rhythm. But a significant minority have worries other than what topics might appear on the exam paper, writes Dr Muiris Houston.
Hay fever, or seasonal allergic rhinitis, affects thousands of Irish people. With 120,000 students taking Leaving and Junior Certificate exams, the weather and the physical conditions of the exam hall could determine how those with a seasonal allergy perform. If the exam weeks coincide with good weather, for example, then supervisors may open windows to help cool the examinees. But opening windows, whether in buildings or cars, is the last way to help sufferers.
Hay fever is an allergic reaction to pollen from trees and grass. The pollen irritates sufferers' upper respiratory passages - the nose, sinuses and throat - and eyes. Once these tiny particles get into the nose, the body's immune system reacts as if they were toxic; it produces antibodies and releases histamine. The result is the classic hay-fever symptoms of blocked or running nose, uncontrollable sneezing, an itchy feeling in the throat and itchy or running eyes.
People with hay fever often report a wheeze in the chest, underlying the finding that about 40 per cent of patients with allergic rhinitis have asthma. Rhinitis usually precedes asthma, although both diseases can occur together.
Writing in Modern Medicine Of Ireland magazine, Dr Paul Carson, the medical author and a GP with a special interest in allergies, has described the link between upper- and lower-airways symptoms as United Airways disease. Recent research suggests the possibility of a physiological mechanism common to both parts of the airway, leading to this concept. As this link is fleshed out, it offers the possibility of a different approach to the treatment of both asthma and hay fever.
Early June means we are well into the grass-pollen season. It usually lasts until July. Tree pollen tends to cause most problems between March and May; birch, hazel and chestnut trees are the main culprits. Fungal spores come later in the season and persist through to September. But global weather-pattern changes are altering this classical division of the hay-fever season.
A pollen count is the number of pollen grains in each cubic metre of air sampled, averaged over 24 hours. A low count is 0-30 grains. Most sufferers will start to experience problems when the count reaches the moderate category of 30-49 grains. Levels between 50 and 149 grains are considered high. The pollen count on a given day is affected by the amount of sunshine or rain and by the speed of the wind. City levels generally peak in the late afternoon and early evening. Rural levels can peak between 7 a.m. and 11 a.m. and again between 4 p.m. and 7 p.m.
Treatment is both oral and topical. When eye symptoms predominate, sodium cromoglycate eye drops are best. For nasal stuffiness or runniness, a topical steroid or a decongestant is the treatment of choice.
Oral antihistamine tablets are available both over the counter and on prescription. Modern antihistamines do not sedate; that said, it is best to take the first dose at night and not before driving or operating machinery.
Patients who do not respond to antihistamines, decongestants and topical steroids may need a short course of oral steroids. Carefully selected patients may also be offered a one-off injection of intramuscular steroid. And a small minority of people with hay fever will need specialist assessment and treatment, which may include immunotherapy: a series of injections with the allergen in a bid to desensitise the immune system. The treatment is not generally available and should be offered only by specialist centres with experience in the procedure.
A critical factor in obtaining the best treatment is to tell the doctor which symptoms bother you most. Matching treatment to the dominant symptoms is the key to relief. In the meantime, you may find these tips useful for preventing symptoms.
Stay indoors if you can. Otherwise, keep doors and windows closed.
Try to avoid newly mowed grass; picking fruit and flowers may exacerbate symptoms.
Try to use a car with a pollen-filtering system or air conditioning.
Wear close-fitting sunglasses.
Try to holiday in dry, hot climates. Pollen levels also tend to be lower in coastal and mountainous areas.
Follow pollen-count reports carefully. One pollen-count and forecast service, including email and text-alert updates, is offered by www.eirpharm.com.
You can email Dr Muiris Houston at mhouston@irish-times.ie. He regrets he cannot answer individual queries