MEDICAL MATTERS Dr Muiris HoustonJudging from the number of snuffling noses and running eyes arriving in doctors' surgeries at present, the hay fever season has well and truly arrived.
The annual scourge of thousands of Irish people will continue to be a problem until September.
One in five people suffer with hay fever but only a small percentage of these require medical treatment. The majority self-medicate or consult a pharmacist.
Hay fever is an allergic reaction to pollens 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 to them 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.
The grass pollen season starts in May and 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 per cubic metre of air sampled, averaged over 24 hours.
A low count is 0-30 pollen grains. Most sufferers will start to experience problems when the pollen count reaches the moderate category of 30-49 pollen grains. Levels between 50 and 149 are considered high.
The pollen count on any given day is affected by the amount of sunshine or rain and by the speed of the wind.
City levels generally peak in late afternoon and early evening. Rural levels peak between 7 and 11 a.m. and again between 4 and 7 p.m.
The challenge in hay fever, both for the patient and the family doctor, is to pitch the treatment at a level appropriate to the severity of the condition while avoiding any side-effects that could render the cure worse than the disease.
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 anti-histamine tablets are available both over the counter and on prescription.
Modern anti-histamines do not sedate; that said, it is best to take the first dose at night and not prior to driving or operating any type of machinery.
Patients who do not respond to anti-histamines, decongestants and topical steroids may need to take a short course of oral steroids.
Carefully selected patients may also be offered a once-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 identified 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 the treatment to the dominant symptoms is the key to relief. In the meantime, you may find these tips useful in 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 also.
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 mountain areas.
Follow pollen count warnings in weather bulletins.
Dr Muiris Houston is pleased to hear from readers at mhouston@irish-times.ie but regrets he cannot answer individual queries.