Pourquoi certaines personnes développent-elles soudainement le rhume des foins ?

Why have I suddenly developed hay fever?

It's a common myth that rhume des foins is something that always develops in childhood. Around 1 in 5 people with this condition develop hay fever symptoms for the first time when they're over 20. So what might cause us to develop hay fever and how can we manage our symptoms?

The chance of developing an allergic reaction is in your genes. Around 1 in 3 adults in the Western world are thought to be potentially susceptible to developing an allergy. However, this is only a susceptibility - many people born with these tendencies will never go on to develop active symptoms.

Dr Runa Ali, consultant physician in Allergy and Asthma in London, says: "Most people only carry antibodies to viruses and bacteria. But 1 in 3 people also carry antibodies to common things such as pollen or peanuts. However, of this number, only one half will go on to develop real-life symptoms."

What are the triggers for allergies?

We know that some people are susceptible to allergies such as hay fever in later life. However, why some of us go on to develop an active allergy is not yet fully understood.

Ali explains that theories about what might shake up your immune system include having a severe infection such as pneumonie, being exposed to pollution, or going through hormonal changes.

"However, even if we identified the people who were susceptible, it wouldn't give us any warning about who will end up being allergic and who wouldn't," she adds. "In fact, if you knew you could react to a certain allergen, you might avoid it - this can be counter-productive, as exposing yourself may keep you tolerant."

This is completely different for people with a proven allergy, especially severe ones such as anaphylaxis, where total avoidance of any exposure to the allergen is important.

The important thing is to remember that an allergy - such as hay fever - may develop at any time. If you start experiencing symptoms of hay fever or another allergy, make sure you speak with your pharmacist or doctor for advice.

What are the symptoms of hay fever?

However, people who don't realise they can develop hay fever as an adult might assume they have a cold - and without the right remedies or approach, may be dealing with the symptoms for several weeks unnecessarily.

This could also make things worse. People whose symptoms are drawn out may also go on to develop secondary symptoms such as tiredness, irritability, récurrents, and low mood.

On the other hand, some people who have been diagnosed with hay fever may write off other symptoms they are experiencing, assuming they are also to do with their allergy. However, this is not necessarily the case and any new or unusual symptoms should be treated with individual concern.

"It's important to remember that typical hay fever symptoms are very mild," explains Ali. "People need to remember, too, that hay fever symptoms are primarily airway-related and there aren't often strange symptoms that go with it."

Can you prevent hay fever?

There's no way to prevent hay fever or another allergy if you are born with a susceptibility. However, there are plenty of remedies that will relieve your symptoms.

If you think you may be dealing with hay fever, there are both over the counter and prescribed medicines that can soothe your symptoms.

If you find that over the counter measures are not helping, book in with your doctor to check whether you have hay fever, or to see if something else is going on such as sinusitis.

How can we protect ourselves against hay fever?

As well as taking any prescribed or recommended medicine, there are other things you can do to reduce your chance of symptoms.

Ali advises that the pollen count is often higher at night, so if you suffer from hay fever you should try to sleep with the windows closed.

"When you drive, it's also helpful to use the air conditioning rather than opening the windows," she says. "Taking holidays by the sea where the grass pollen count is low is a good idea, as is avoiding overly grassy areas when possible.

Finally, wearing glasses or sunglasses can provide some protection for your eyes."

While you can't control whether you develop hay fever, by knowing that the condition can develop at any age, you're more likely to seek the right help in time for the season.

Taking medicine and sensible precautions should mean that you can get outside and enjoy the warmer weather.