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ACAAI > Patients & Public > Asthma > Asthma and Other Conditions

The Flu and Asthma

Asthma, a chronic inflammation of the lung airways, affects an estimated 20.3 million Americans. It is more common in children than adults, with about 6.3 million children suffering from the disease. Symptoms of asthma include persistent coughing (especially at night), wheezing and difficulty breathing. Although the exact cause of asthma is unknown, experts do know that symptoms can be caused by a variety of triggers, including exercise, exposure to allergens such as pollens, dust mites, mold spores and pet dander, exposure to inhaled irritants such as household cleaners and tobacco smoke, and viral infections.

Influenza, also called the flu, is a contagious respiratory illness caused by viruses. Millions of people in the United States – about 10 percent to 20 percent of U.S. residents – will get the flu each year. Unlike many other viral respiratory infections, such as the common cold, the flu can cause severe illness and life-threatening complications. Each year, an average of 36,000 Americans die from flu-related complications such as pneumonia and acute respiratory disease. The risk is greater for very young children, people age 65 and older, and people who have chronic medical conditions such as asthma.

Because both asthma and the flu are respiratory conditions, people with asthma may experience more frequent and severe asthma attacks while they have the flu.

How is influenza spread and what are its symptoms? 

Influenza is a contagious disease that attacks the respiratory tract, including the nose, throat and lungs. Symptoms include fever, headache, fatigue, dry cough, sore throat, nasal congestion and body aches. Flu is spread when an infected person coughs or sneezes, spraying droplets into the air and onto nearby people. It can also be spread by touching droplets on another person or object and then touching your own mouth or nose before washing your hands. Infected people can spread the virus one day before developing symptoms and up to seven days after getting sick.

How can you tell if you have the flu?

Because many flu symptoms are similar to those of other respiratory infections, including the common cold, the only way to be sure it’s the flu is to see your doctor. There are tests that can determine if you have the flu as long as you are tested within the first two or three days after your symptoms begin. In general, if your respiratory symptoms are accompanied by sudden onset of body aches and fever, and occur during flu season, suspect the flu.

When is flu season?

In the United States, peak flu season months are December, January and February but flu season can last from November through March. For the past 21 years, February has had the most cases of flu during the season, according to the Centers for Disease Control and Prevention (CDC). 
In most parts of the U.S., flu season does not correspond with periods of peak pollen counts, which can trigger and aggravate asthma in those who are allergic.

How can you prevent the flu?

The best way to prevent the flu is to get vaccinated each fall. This is particularly important for those who have chronic respiratory conditions such as asthma. The vaccination works by triggering the development of antibodies that fight the flu virus when the body is exposed to it. There are two types of flu vaccines: injections (the flu shot) and a nasal spray.

Those who have asthma or other chronic medical conditions should get the shot, which is an activated vaccine (containing killed virus). The best time to get the flu shot is in October or November, because it typically takes about two weeks for sufficient antibodies to develop.
The flu shot is approved for use among very young children, including healthy people and those with chronic medical conditions, such as asthma.

Allergists, physicians who specialize in treating asthma and allergies, urge everyone who has asthma to get the flu vaccination as part of their routine care. Flu viruses change from year to year, and you can get the flu more than once in your lifetime, so being vaccinated one year will not necessarily protect you from newer viruses in subsequent years. According to the CDC, only 
one-third of asthmatic adults receive the flu vaccine annually, and only one-fifth of asthmatic adults younger than 50 years of age receive the vaccine annually.

The second type of flu vaccine, called the nasal-spray flu vaccine, contains attenuated (weakened) live viruses, and is administered by nasal sprayer. It is approved for use only among healthy people between the ages of 5 and 49 years. Because it contains live viruses, the nasal-spray flu vaccine can provoke or aggravate asthma symptoms in those who have the chronic condition and should not be used.

Those who are allergic to eggs should consult their doctor before receiving either the flu shot or the nasal spray flu vaccine.

What should you do if you get the flu?

The best strategy for recovering from the flu is to rest, drink plenty of fluids and avoid using alcohol and tobacco. You can take over-the-counter medications to relieve the symptoms of the flu, but never give aspirin to children or teenagers who have flu-like symptoms – particularly fever – without consulting a doctor first.

Giving aspirin to children and teenagers who have the flu can cause a rare but serious illness called Reye’s syndrome.

Your doctor also may prescribe an antiviral medication to treat the flu infection, but these medications are effective only if started within the first two days of experiencing symptoms.

For more information about asthma and its diagnosis and treatment, visit the American College of Allergy, Asthma and Immunology (ACAAI) Web site at

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