What is Hay fever?

Hay fever

What is hay fever?

If you have hay fever, you're probably allergic to pollen. That's why you get symptoms in the spring, summer or fall, when there's lots of pollen around.

Hay fever can make you feel miserable. You sneeze a lot and your nose runs or feels stuffed up. Your eyes may be red, itchy or watery. And you may have a cough or a wheeze.

You may get hay fever so badly that you can't sleep, can't concentrate and find it hard to work. And at certain times of the year, pollen is hard to avoid. But there are good treatments that can help you feel better. You may need to start treatment before the pollen season begins and before you get symptoms.

Hay fever is also called seasonal allergic rhinitis or intermittent allergic rhinitis.

Key points for people with hay fever

If you have hay fever, you're probably

allergy
If you have an allergy to something, your body overreacts when you're around it. The thing you are allergic to is called an allergen. Most allergens are harmless to most people. But if you're allergic to something, your body's system for fighting infection (your immune system) is too sensitive to that allergen. It triggers changes that we call allergic reactions. For example, pollen is an allergen for many people. If you're allergic to pollen, you'll sneeze and have runny eyes when pollen is in the air.

allergic to pollen.
Some people with hay fever are allergic to

molds
Molds are a type of fungus that can cause health problems. For example, you can get infections caused by molds, or you can have an allergy to molds. If you're allergic to them, you have a reaction when you breathe in tiny seeds they give off (called mold spores).

mold.
You get hay fever at times of the year when there's lots of pollen or mold around.
If you have hay fever, it's a good idea to avoid pollen or mold as much as you can. (To find out more, see Avoiding pollen and mold.)
Treatments can help get your hay fever under control.
The good news is that hay fever may go away as you get older.

Source:
Rosenwasser LJ.
Treatment of allergic rhinitis.
American Journal of Medicine. 2002; 113: 17-24.

¹

Source:
Conner SJ.
Evaluation and treatment of the patient with allergic rhinitis.
The Journal of Family Practice. 2002; 51: 883-890.

²

Your immune system

To understand why you get an allergy like hay fever, it helps to know a little about your immune system.

Source:
National Institute of Allergy and Infectious Diseases.
Understanding the Immune System. How it Works.
Available at http://www.niaid.nih.gov/publications/immune/the_immune_system.pdf (accessed on 7 August 2007).

Source:
National Institute of Allergy and Infectious Diseases (NIAID). NIH.
Something in the air: airborne allergens.
April 2003. Available at http://www.niaid.nih.gov (accessed on 2 July 2008).

⁴

Your immune system helps protect you from things that can make you ill, such as

bacteria
Bacteria are tiny organisms. There are lots of different types. Some are harmful and can cause disease. But some bacteria live in your body without causing any harm.

bacteria and

viruses
Viruses are microbes (tiny organisms) that need the cells of humans or other animals to exist. They use the machinery of cells to reproduce. Then they spread to other cells in the body.

viruses.
Your immune system is made up of lots of special cells.
These cells are found all over your body, including inside your nose, at the back of your throat and in your lungs.
The ones in your nose, throat and lungs are there to protect you against the kinds of

infection
You get an infection when viruses, bacteria, fungi or other tiny organisms get into your body. These bugs are so tiny that you can't see them without a microscope. For example, an infection in your airways causes the common cold. And an infection in your skin can cause rashes such as athlete's foot.

infections you can get in your airways, such as colds or

pneumonia
Pneumonia is an infection in your lungs. Anything that causes infections (bacteria, viruses or fungi, for example) can give you pneumonia.

pneumonia.

What happens when you get hay fever?

Hay fever is an allergy. You have an allergy when your immune system has an abnormal reaction to something that's normally harmless.

It mistakes something harmless for something that is harmful and tries to attack it or get rid of it. And this gives you symptoms such as sneezing, a stuffed-up nose, and itchy or watery eyes.

Sneezing is a common symptom of hay fever.

Most people with hay fever are allergic to pollen.

Source:
National Institute of Allergy and Infectious Diseases (NIAID). NIH.
Something in the air: airborne allergens.
April 2003. Available at http://www.niaid.nih.gov (accessed on 2 July 2008).

⁴ Plants release pollen in the spring, summer or fall. Pollen is like a very fine dust, and you can't always see it.

But some people with hay fever are allergic to mold. Mold is a type of fungus that grows in damp, shady places. Its seeds are called spores. Like pollen, these spores are carried through the air.

To learn more, see More about what happens in hay fever.

When you have hay fever, breathing in exhaust fumes, cigarette smoke or perfume may make your symptoms worse.

Source:
Togias A.
Unique mechanistic features of allergic rhinitis.
Journal of Allergy and Clinical Immunology. 2000; 105: 599-604.

⁵

More about pollen

There are many different types of pollen. Pollen is released by different plants at different times of the year. Most people with hay fever are allergic to the pollen made by trees, grasses or weeds. You may be allergic to only one type of pollen or to more than one.

Pollen from ragweed is the most common trigger for hay fever. Ragweed grows by the side of the road, in empty lots and in fields.

Source:
American academy of allergy, asthma and immunology.
Tips to Remember: Outdoor Allergens.
April 2006. Available at http://www.aaaai.org (accessed on 2 July 2008).

⁶
In most parts of the United States, ragweed releases pollen in the fall. So if you're allergic to ragweed, this is when you'll get symptoms of hay fever.

Plants like ragweed release huge amounts of pollen into the air. That makes pollen very hard to avoid. And in the United States, there are lots of plants that cause allergies.

Source:
National Institute of Allergy and Infectious Diseases.
Something in the air: airborne allergens.
April 2003. Available at http://www.niaid.nih.gov (accessed on 2 July 2008).

⁷

Ragweed (Photo from the American Academy of Allergy, Asthma and Immunology)

To find out more, see Plants that give you hay fever.

More about molds

Outside, you can find mold on rotting logs and fallen leaves, in compost piles and on certain grasses and weeds. Mold can also grow on damp spots inside your house, such as in your basement.

Source:
National Institute of Allergy and Infectious Diseases (NIAID). NIH.
Something in the air: airborne allergens.
April 2003. Available at http://www.niaid.nih.gov (accessed on 2 July 2008).

⁴ There are thousands of different types of mold, but fortunately, only a few cause allergies.

Source:
Conner SJ.
Evaluation and treatment of the patient with allergic rhinitis.
The Journal of Family Practice. 2002; 51: 883-890.

Source:
National Institute of Allergy and Infectious Diseases (NIAID). NIH.
Something in the air: airborne allergens.
April 2003. Available at http://www.niaid.nih.gov (accessed on 2 July 2008).

⁴

When will I get hay fever?

You may be able to help yourself by figuring out when you're most likely to get symptoms of hay fever. This can help you be ready. For example, you need to start using some treatments before there's pollen or mold spores in the air. (To find out more, see Steroid nasal sprays.)

You can get symptoms of hay fever at any time of the year when pollen or mold spores are around, which could be in the spring, summer or fall. Exactly what time of year you get them depends on what you're allergic to and where you live.

Pollen: Generally, the farther north you live, the later pollen is released. So if you live in New York, for example, you'll probably get hay fever symptoms later in the year than someone who lives in Florida.

Source:
National Institute of Allergy and Infectious Diseases (NIAID). NIH.
Something in the air: airborne allergens.
April 2003. Available at http://www.niaid.nih.gov (accessed on 2 July 2008).

⁴ To find out more about the pollen season where you live, see our Pollen maps.
Mold: If you're allergic to mold, you may have symptoms from spring to late fall. And your symptoms may be at their worst from July to late summer.

Source:
National Institute of Allergy and Infectious Diseases.
Allergies: Questions and answers
February 2000. Available at http://www.medhelp.org/NIHlib/GF-490.html (accessed on 1 July 2008).

⁸

The pollen count

You've probably heard of pollen counts or pollen forecasts. They're often mentioned in weather reports. They tell you how much pollen is in the air.

The pollen count is usually measured in grains of pollen per square meter of air, based on an average collected over 24 hours. (A meter is a bit longer than a yard.) The count can be low, moderate or high. The higher it is, the more likely it is that people with hay fever will get symptoms.

Source:
National Institute of Allergy and Infectious Diseases (NIAID). NIH.
Something in the air: airborne allergens.
April 2003. Available at http://www.niaid.nih.gov (accessed on 2 July 2008).

⁴ So you can use pollen forecasts to help you predict the days when you're likely to have symptoms.

Pollen counts tend to be higher on warm, dry, breezy days and lower on cold, wet days.

Source:
National Institute of Allergy and Infectious Diseases.
Allergies: Questions and answers
February 2000. Available at http://www.medhelp.org/NIHlib/GF-490.html (accessed on 1 July 2008).

⁸

The National Allergy Bureau monitors pollen counts in many areas of the United States.

Source:
American Academy of Asthma, Allergy and Immunology
NAB: US Pollen Seasons.
Available at www.aaaai.org (accessed on 2 July 2008).

⁹ You can call their toll-free number to see what the count is in your area: (800) 9-POLLEN.

What's the worst time of day for pollen?

Pollen levels are usually highest early in the morning, between 5 a.m. and 10 a.m. So that's the worst time to be outside if your hay fever is triggered by pollen.

Other allergies

If you have hay fever, you may also be allergic to things besides pollen or mold. Two of the most common triggers for allergies are

dust mites
Dust mites are tiny creatures that live in dust. You can't see them with your naked eye. Many people have an allergy to dust mite droppings.

dust mites and furry pets such as cats and dogs.

Source:
National Institute of Allergy and Infectious Diseases.
Allergies: Questions and answers
February 2000. Available at http://www.medhelp.org/NIHlib/GF-490.html (accessed on 1 July 2008).

⁸ Allergies to these things can give you symptoms similar to hay fever.

If you have an allergy that gives you a runny nose or a stuffed-up nose, or an allergy that makes you sneeze, your doctor may call it allergic rhinitis.

Source:
Skoner DP.
Allergic rhinitis: definition, epidemiology, pathophysiology, detection, and diagnosis.
Journal of Allergy and Clinical Immunology. 2001; 108: 2-8.

¹⁰ There are two main types. Many people get both types.

Seasonal (or intermittent) allergic rhinitis: This is hay fever. You have this if you're allergic to pollen or mold and you only get your symptoms at certain times of the year.
Perennial (or persistent) allergic rhinitis: You have this if you're allergic to something like dust mites or pets. Your symptoms last most of the year.

You can get other allergies along with hay fever. Two common ones are:

Eczema, a condition that makes your skin dry, red and itchy
Asthma, a condition that makes you cough and wheeze. Most people who have asthma also have allergic rhinitis.

Source:
Bachert C, van Cauwenberge P.
The WHO ARIA (allergic rhinitis and its impact on asthma) initiative.
Chemical Immunology and Allergy. 2003; 82: 119-26.

¹¹

To find out more, see Eczema, Asthma in adults and Asthma in children.

But isn't it just a cold?

If you have an allergy like hay fever, you may think you have a cold. The symptoms can be similar. But it's important to know the difference between them. The treatments are different, and if you have hay fever and the symptoms are bothering you, treatment may help.

Here are some of the differences between having hay fever and having a cold.

Source:
American Academy of Allergy, Asthma and Immunology.
Control your allergies and asthma. Is it really an allergy?
2003. Available at www.aaaai.org/springallergy/2003/reallyanallergy.stm (accessed on 1 July 2008).

¹² But if you're not sure which you have, it's a good idea to check with your doctor.

	Hay fever	Cold
What causes it?	Usually pollen, but sometimes mold	Viruses
How long does it last?	As long as you breathe in pollen or mold spores, and for some hours afterward	Several days to a week
When do you get it?	Only during the pollen or mold season, in the spring, summer or fall	Any time of the year, but most often in the winter
When do symptoms start?	As soon as you breathe in pollen or mold spores	Usually a few days after you were around someone with a cold
What are the symptoms?	Sneezing, an itchy throat or tickly cough, a runny, stuffed-up or itchy nose, with itchy, red and watery eyes	Fever, feeling achy, sneezing, a runny or stuffed-up nose

Why me?

Certain things make it more likely that you'll get hay fever. These are called risk factors.

Two of the main risk factors for hay fever are:

Source:
Sly M.
Changing prevalence of allergic rhinitis and asthma.
American College of Allergy, Asthma and Immunology. 1999; 82: 233-252.

¹³

Having someone in your family who has allergies.
Having other allergies, for example to dust mites.

Having risk factors doesn't mean you'll definitely get hay fever. It just means that you're more likely to get it.

To find out more, see Risk factors for hay fever.

Sources for the information on this page:

Rosenwasser LJ.Treatment of allergic rhinitis.American Journal of Medicine. 2002; 113: 17-24.

Conner SJ.Evaluation and treatment of the patient with allergic rhinitis.The Journal of Family Practice. 2002; 51: 883-890.

National Institute of Allergy and Infectious Diseases.Understanding the Immune System. How it Works. Available at http://www.niaid.nih.gov/publications/immune/the_immune_system.pdf (accessed on 7 August 2007).

National Institute of Allergy and Infectious Diseases (NIAID). NIH.Something in the air: airborne allergens.April 2003. Available at http://www.niaid.nih.gov (accessed on 2 July 2008).

Togias A.Unique mechanistic features of allergic rhinitis.Journal of Allergy and Clinical Immunology. 2000; 105: 599-604.

American academy of allergy, asthma and immunology.Tips to Remember: Outdoor Allergens.April 2006. Available at http://www.aaaai.org (accessed on 2 July 2008).

National Institute of Allergy and Infectious Diseases.Something in the air: airborne allergens.April 2003. Available at http://www.niaid.nih.gov (accessed on 2 July 2008).

National Institute of Allergy and Infectious Diseases.Allergies: Questions and answersFebruary 2000. Available at http://www.medhelp.org/NIHlib/GF-490.html (accessed on 1 July 2008).

American Academy of Asthma, Allergy and ImmunologyNAB: US Pollen Seasons.Available at www.aaaai.org (accessed on 2 July 2008).

Skoner DP.Allergic rhinitis: definition, epidemiology, pathophysiology, detection, and diagnosis.Journal of Allergy and Clinical Immunology. 2001; 108: 2-8.

Bachert C, van Cauwenberge P.The WHO ARIA (allergic rhinitis and its impact on asthma) initiative.Chemical Immunology and Allergy. 2003; 82: 119-26.

American Academy of Allergy, Asthma and Immunology.Control your allergies and asthma. Is it really an allergy?2003. Available at www.aaaai.org/springallergy/2003/reallyanallergy.stm (accessed on 1 July 2008).

Sly M.Changing prevalence of allergic rhinitis and asthma.American College of Allergy, Asthma and Immunology. 1999; 82: 233-252.

This information was last updated on May 01, 2009

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