Flu (Influenza)

The flu is a contagious respiratory infection caused by influenza viruses that spread easily. It can cause mild to severe illness. The flu causes thousands of hospitalizations and deaths every year, including previously healthy children and adults.

The flu can affect your lungs when you have asthma. It can cause swelling and narrowing of your airways. This can trigger asthma symptoms, an asthma episode, or an asthma attack. If you have asthma, protecting yourself from the flu is very important.

Many people recover from the flu without problems. But having asthma puts you at risk of serious health problems from the flu.1

Common Flu Symptoms

The flu usually starts suddenly and may include these symptoms:

  • Fever (often very high, 101 or above)
  • Headache
  • Extreme tiredness, chills
  • Constant cough
  • Sore throat
  • Runny or stuffy nose
  • Body aches in bones and/or muscles
     

Diarrhea and vomiting also can occur but are more common in children. These symptoms are called “flu-like symptoms.”

Common Emergency Flu Symptoms

Some signs and symptoms need emergency medical care right away. Call 911 if you or your child has these symptoms.

For children, emergency symptoms include:

  • Rapid breathing or difficulty breathing
  • Cyanosis which is tissue color changes on mucus membranes (like tongue, lips, and around the eyes) and fingertips or nail beds – the color appears grayish or whitish on darker skin tones and bluish on lighter skin tones
  • Not waking up or not conscious
  • Being irritable and difficult to comfort
  • Flu-like symptoms seem to improve but return with worse fever and cough
  • Fever with a rash
     

For adults, emergency symptoms include:

  • Rapid breathing or difficulty breathing
  • Pain in the chest or abdomen
  • Sudden dizziness
  • Confusion
  • Severe or persistent vomiting
     

How Does the Flu Spread?

Unlike asthma, the flu is contagious. The flu spreads from coughing and sneezing. It usually spreads from person to person. You can also get the flu by touching something with the flu virus on it, then touching your mouth or nose. You can spread the flu before you know you are sick and when you are sick.

The flu spreads from fall through spring each year.

Diagnosing the Flu

There are tests that can tell if you have the flu. But testing is most accurate if it is done within the first three days of illness. You may also need a doctor’s exam to tell if you have an infection that is a complication – a serious health problem – from the flu, like pneumonia.

Many different illnesses can have the same symptoms and can sometimes be confusing. Symptoms from other illnesses like COVID-19, the common cold, allergies, or asthma can be similar to the flu. COVID-19 testing is widely available, but you may need a clinic appointment to get tested for the flu. Visit or talk with your doctor to get a proper diagnosis.

Treating the Flu

There are antiviral drugs approved to treat flu. Talk with your doctor about these prescription medicines. You need to start antiviral treatments within two days of when you start to have symptoms. If you get flu-like symptoms, contact your doctor right away.

Get plenty of rest, drink plenty of liquids, and avoid using alcohol and tobacco. Before taking over-the-counter medicines to help relieve flu symptoms, talk with your doctor. Some over-the-counter medicines or supplements can interfere with other medicine you may be taking.

Preventing the Flu

There are some easy things you can do to avoid getting and spreading the flu:

  • Get the flu vaccine. The CDC recommends that people ages 6 months and older should get the flu vaccine.
  • Wash your hands often for at least 20 seconds with soap and warm water, especially after coughing or sneezing. If you don’t have access to running water, use an alcohol-based hand sanitizer.
  • Don’t touch your eyes, nose, or mouth.
  • Stay away from people who are sick.
  • If you get the flu or have flu-like symptoms, stay home from work or school.
     

It is possible to also get other illnesses such as COVID-19 or respiratory syncytial virus (RSV) at the same time as the flu and become very sick. Getting the flu vaccine can help reduce your or your child’s risk of severe illness from more than one respiratory infection.

Special Information for People With Asthma

Flu viruses change from year to year. So, the flu vaccine changes each year. The CDC also updates its guidelines each year. Get a flu vaccine every year when it becomes available, usually between August and October.

The vaccine is safe. If you have asthma, the risks of flu complications are far greater than not getting the vaccine.

If you care for children with asthma or live with people with asthma, get the flu vaccine to protect them.2

The flu vaccine is available as a shot or a nasal spray. AAFA recommends the following:

  • Ages 6 months to 4 years: Get the flu shot.
  • Ages 4 and older: If your asthma is under control with no symptoms, you can get the flu shot or the nasal spray vaccine.
  • Ages 4 and older: If you have recent asthma episodes or wheezing, get the flu shot.

If you have asthma and get the flu, contact your doctor right away. You are at greater risk of becoming severely ill with health problems from the flu very quickly.

Special Information for People With Allergies

If you have ever had either of the following, you should check with your allergist to ask if the flu vaccine is safe for you:

  • A life-threatening allergic reaction after a dose of flu vaccine
  • A severe allergy to any part of a flu vaccine (other than egg proteins)
     

Egg Allergy and Flu Vaccine
Egg allergy is not a reason to avoid the flu vaccine. It is safe for ALL people with an egg allergy to receive an annual flu vaccine. This is true no matter how severe your egg allergy was in the past. This includes anaphylaxis (a severe allergic reaction) to egg.

The following organizations recommend getting the flu vaccine every year, even if you have an egg allergy:

  • Asthma and Allergy Foundation of America (AAFA)
  • Centers for Disease Control and Prevention (CDC)
  • American Academy of Pediatrics
  • American Academy of Allergy, Asthma, and Immunology (AAAAI)
  • American College of Allergy, Asthma, and Immunology (ACAAI)
     

You can get any flu vaccine, even if you have a history of mild or severe egg allergy. You can get the shot or nasal spray, depending on the recommendations above if you have asthma. You no longer need to be observed in a doctor’s office for 30 minutes after getting the vaccine if you have or had an egg allergy.

The CDC makes the following recommendations for people with an egg allergy who get the flu vaccine:3

  • Anyone who has only hives from egg can receive any licensed and recommended flu vaccine for their age and health status.
  • Anyone who has had a reaction to egg other than hives should get the flu shot in a medical facility from a health care provider who can recognize and treat a severe allergic reaction.
  • Anyone who has had a severe allergic reaction to the flu vaccine in the past should not get the flu vaccine.
     

The AAAAI and ACAAI state that the vaccine is safe to give in any setting. There is no special waiting time or other precautions.4

The flu vaccine is safe, even for people with egg allergy

Latex Allergy and Flu Vaccine
If you have a latex allergy, check with your doctor before getting a flu vaccine. Latex could be in the flu vaccine vials or the syringes used to give the flu shot.

Severe Allergic Reactions
Allergic reactions (including anaphylaxis) after the flu vaccine are serious but rare.

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Flu vaccine handout

Medical Review April 2021 by Sarah Goff, MD, PhD, and October 2021 by David Stukus, MD

 

References
1. Flu and People with Asthma | Seasonal Influenza (Flu) | CDC. (2019). Cdc.gov. Retrieved October 14, 2021, from https://www.cdc.gov/flu/asthma/index.htm
2. Who Needs a Flu Vaccine and When. (2019). Centers for Disease Control and Prevention. Retrieved October 14, 2021, from https://www.cdc.gov/flu/consumer/vaccinations.htm
3. Centers for Disease Control and Prevention. (2020, September 22). Flu vaccine and people with egg allergies. Centers for Disease Control and Prevention. Retrieved October 14, 2021, from https://www.cdc.gov/flu/prevent/egg-allergies.htm#recommendations.
4. Greenhawt, M., Turner, P. J., & Kelso, J. M. (2018). Administration of influenza vaccines to egg allergic recipients: A practice parameter update 2017. Annals of Allergy, Asthma & Immunology, 120(1), 49–52. https://doi.org/10.1016/j.anai.2017.10.020