Flu (Influenza)

The flu is a respiratory infection caused by influenza viruses that spread easily. It can cause mild to severe illness. It can also cause death in severe cases. If you have asthma, protecting yourself from the flu is very important.

The flu can affect your lungs when you have asthma. It can cause your airways to swell and narrow. This can trigger asthma symptoms (an asthma episode or attack).

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

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

If you develop any of the symptoms above and trouble breathing, contact your doctor right away.

Diarrhea and vomiting also can occur but are more common in children. These symptoms are called “flu-like symptoms.” Many different illnesses can have the same symptoms and sometimes be confusing. This includes the common cold, allergy symptoms, and asthma symptoms. Talk with your doctor to get the right diagnosis.

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 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 October through May 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 of the flu.

Treating the Flu

There are antiviral drugs approved to treat flu. Talk to 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 to 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 shot.
  • 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, stay home from work or school.

Special Information for People With Asthma

  • If you have asthma, get the flu vaccine (shot). Do NOT get the nasal spray vaccine. The nasal spray could trigger asthma symptoms or an asthma attack.
  • Flu viruses change from year to year. So, the flu shot changes each year. Get a flu shot every year when it becomes available, usually between August and October.
  • 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.
  • If you care for children with asthma or live with people with asthma, get the flu shot to protect them.
  • The vaccine is safe. If you have asthma, the risks of the flu are far greater than not getting the vaccine.

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

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

Several research studies have shown the flu shot is safe for people with an egg allergy. The Centers for Disease Control and Prevention (CDC), American Academy of Pediatrics, and the American Academy of Allergy, Asthma, and Immunology (AAAAI), and the American College of Allergy, Asthma, and Immunology (ACAAI) all recommend getting a flu shot even if you have an egg allergy.

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 flu shot are serious but rare.

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Medical Review April 2021 by Sarah Goff, MD, PhD