Hay fever is a type of allergy. It happens when your body makes antibodies in response to certain triggers, such as pollen.
The charity Allergy UK estimates that nearly 18 million people have hay fever in the UK. It's most common in children, particularly teenagers, but you can develop hay fever at any age.
The symptoms usually include sneezing, itchy and watery eyes, and a stuffy nose.
Read more about the symptoms of hay fever.
What causes hay fever?
In Britain, hay fever is mainly caused by grass pollen. Around 95% of hay fever sufferers are allergic to grass pollen.
Tree pollen can cause hay fever too. Around a quarter of hay fever sufferers are allergic to tree pollen. Mould spores and weed pollen can also trigger symptoms.
This is because your body sees these pollens as a threat, so your hay fever symptoms are caused by your immune system attempting to prevent the spread of what it mistakenly thinks is a harmful organism.
Check this Met Office pollen calendar to see if you're allergic to tree, grass or weed pollen.
The pollens that cause hay fever vary from person to person and from region to region. The amount of pollen in the air will affect how bad your hay fever is.
It's more likely that there will be more pollen in the air on hot, dry, windy days than on cool, damp, rainy days. Research shows that pollution, such as cigarette smoke or car exhaust fumes, also makes some allergies worse. Pollen can also attach to clothing, hair and pets' fur, which means it can be hard to avoid even indoors.
Read more about the causes of hay fever.
When is hay fever worst?
The time of year when you begin to experience hay fever symptoms depends on the types of pollen you're allergic to.
Trees release their pollen in March to early May, while grasses release pollen from late May to early August. Weeds and certain shrubs release their pollen in late summer.
The hay fever season can therefore last from March to October. And if you're unlucky enough to be allergic to more than one type of pollen, you may only have just two or three months without symptoms in the winter before the cycle starts again.
Find out how the weather affects hay fever symptoms.
How can I avoid getting hay fever?
If your parents are allergic to something, you're more likely to develop an allergy too (it doesn't have to be the same allergy as your parents).
If you smoke while you're pregnant or smoke around your child, your child could be more likely to develop an allergy. Not smoking and eating a healthy diet can limit the chances of your children being affected.
Hay fever and asthma
Speak to your GP or pharmacist before you decide on a hay fever treatment. It's particularly important to speak to your GP if you have asthma. Hay fever often makes asthma symptoms worse. If this happens, you may need to increase the dosage of your asthma medication.
As well as aggravating people who already have asthma, hay fever can also triple the likelihood of people developing asthma, according to Allergy UK's 2014 report One Airway One Disease.
Read more about treatments for hay fever.
Hay fever in pregnancy
Hay fever during pregnancy can be a particular problem. Hormonal changes make nasal congestion more common during pregnancy, and this often gets worse during hay fever season. Pregnant women are also advised not to take some hay fever medicines.
Read more about taking hay fever medicines during pregnancy.
Tips to relieve hay fever
Avoiding exposure to pollen is the best way to reduce the allergic symptoms of hay fever:
- Keep windows shut at night and first thing in the morning.
- Stay indoors when the pollen count is high (between 50 and 150).
- Wear wraparound sunglasses.
- Put some petroleum jelly (Vaseline) or another nasal blocker just inside your nostrils to trap some of the pollen.
- Don't mow the grass or sit in fields or large areas of grass.
- Wash your hands and face regularly.
- Avoid exposure to other allergens, such as pet fur, or environmental irritants, such as insect sprays or tobacco smoke.
Get more tips to prevent hay fever.
Check the Met Office pollen forecast to find out your chance of hay fever symptoms over the next five days.
Treating hay fever
As with most allergies, the best way to control hay fever is to avoid the triggers. But it's difficult to avoid pollen, particularly during the summer.
Even straightforward hay fever can be debilitating, causing runny eyes, sleepless nights, a bunged-up nose and headaches.
A range of over-the-counter products can treat the symptoms of hay fever, including tablets, nasal sprays and eye drops.
Antihistamines are the usual treatment for the main symptoms, such as itchy, watery eyes and a runny nose, while steroid nasal sprays are the main treatment for a stuffy nose. Your pharmacist can help advise you on which treatment is best for you.
Talk to your GP or pharmacist about your hay fever
If you have particularly severe hay fever symptoms, you may need a prescription from your GP.
According to the charity Allergy UK, most treatments recommended for people with moderate-to-severe symptoms are not available without a prescription.
But despite this, only one in five hay fever sufferers have ever booked an appointment with a GP or pharmacist to discuss their symptoms and treatment options.