HAY FEVER: SEPARATING FACT FROM FICTION
WITH BETWEEN TEN AND 30 PER CENT OF PEOPLE AFFECTED BY HAY FEVER, SP LOOKS AT THE FACTS – AND THE MYTHS – ABOUT HAY FEVER…
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o, first of all, let’s look at the facts... The United Kingdom (UK) has one of the highest
prevalences of hay fever - or allergic rhinitis - in the world, with the overall rate for the population standing at around 26 per cent, rising to 38 per cent in teenagers. Even more worryingly, a recent report has predicted that the incidence of hay fever in the UK will double by 2030.
Hay fever is essentially a mucosal reaction in response to allergen exposure. It is commonly defined as an Immunoglobulin E (IgE) mediated inflammatory disorder of the nose occurring when the nasal mucosa becomes sensitised to allergens. The subsequent allergic reaction triggers the release of potent inflammatory mediators, primarily histamine, which exert their action via neural and vascular mechanisms. Ultimately, this causes the sufferer to experience the classic symptoms of hay fever: sneezing, itching, rhinorrhoea, nasal obstruction and a post-nasal drip.
Hay fever can develop at any time over the age of two years, but will typically begin during adolescence or early adulthood. Interestingly, late onset cases are becoming increasingly more prevalent, while figures also suggest that fewer people are ‘growing out’ of the condition as they reach adulthood.
While half of people do find their symptoms ease a bit with age - a recent Swedish study found that it was most likely to disappear completely when sufferers were in their 50s - unfortunately, most people’s symptoms will recur annually.
24 - SCOTTISH PHARMACIST
The exact reasons why some people develop hay fever/allergic rhinitis are unclear, although both genetic and environmental factors appear to contribute to its development.
Recognised risk factors include: • Personal history of atopy • Familial history of rhinitis or atopy • Air pollution • Reduced exposure to infection • Exposure to cigarette smoke
Ironically, there is growing evidence to support the ‘hygiene hypothesis’ as a contributing factor to the rising rate of hay fever in the UK, with various studies hypothesising that suffering from fewer infections during childhood, together with a lack of exposure to endotoxins, can disrupt the immune system development, thus increasing the risk of allergic rhinitis.
The condition is generally classified as seasonal, perennial or occupational:
• Seasonal – symptoms occur at the same time each year. If caused by grass or tree pollen allergens, it is also commonly called hay fever. Other allergens include mould spores and weed pollen.
• Perennial – symptoms occur throughout the year. Typically caused by house allergens like dust mites and domestic pets.
• Occupational – symptoms occur due to exposure to allergens at work. Examples include flour, wood dust and latex gloves.
So those are the facts…..but you may be surprised at some of the myths that surround hay fever…
Hay fever is caused by hay In the early 19th century, it was generally assumed that freshly-cut hay caused what we recognise as allergic rhinitis symptoms, hence its popular name ‘hay fever’. A British doctor - James Bostock - discounted this theory, but it was not until 1859 that a British scientist called Charles Blackley made the link with pollen, after sneezing when he sniffed a bouquet of bluegrass. The role that the immune system plays in allergic reactions hadn’t yet been recognised and so Blackley thought that the unpleasant symptoms were caused by toxins in the pollen. Today, scientists have recognised that certain people’s immune systems overreact when they encounter certain types of pollen, triggering hay fever symptoms.
Hay fever symptoms ease after it rains This one is partly true. While light rainfall can help to stop pollen from spreading through the air, heavy rain can often have the opposite effect. Researchers in the United States analysed fourteen years of meteorological and pollen count data and found that levels of pollen fell after less than ten centimetres of rain, but increased if there was more than that. Conclusion? Heavier downfalls seem to whip pollen up – particularly if it’s windy as well.
Hay fever is worse during the day Hay fever sufferers are often advised to stay indoors during the day as pollen levels tend to be higher. This isn’t strictly true, with research confirming that it depends
on the type of pollen that is affecting the sufferer.
A study carried out in Poland entitled “Pollen nightmare: elevated airborne pollen levels at night” saw traps set out on a rooftop and five common types of pollen measured during both daytime and night-time. The study showed that while levels of mugwort pollen were actually lower at night, the levels of ragweed pollen were higher.
Hay fever antihistamines cause drowsiness drowsy This certainly applied to older types of first-generation antihistamines, in which drowsiness was a common side-effect.
Hay fever sufferers tended to experience disturbed sleep because of their symptoms and so didn’t mind the fact that the antihistamines made them sleepy since they were able to get a good night’s sleep.
Since the 1980s, however, the second-generation antihistamines do not cross the blood-brain barrier as easily and so there are few symptoms related to drowsiness – if any.
Honey can reduce the symptoms of hay fever A small American study featured people being given various types of honey or corn syrup to take each day to alleviate their hay fever symptoms.
None of those who took part in the study experienced any improvement in their symptoms.
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