The Facts About the Flu and Asthma

Flu Can Trigger or Worsen Asthma and Cause Serious Complications

In This Article
Table of Contents

Asthma is a chronic lung disease that leads to very sensitive and inflamed airways, and the flu is a contagious respiratory illness that can can contribute to airway and lung inflammation. People with asthma are no more likely to get the flu than those without asthma, but they are more likely to experience complications, such as bronchitis and pneumonia, and require hospitalization.

Even those with mild asthma or well controlled asthma are at a high risk of serious health problems from the flu. This is because influenza causes respiratory inflammation that not only triggers the symptoms of asthma but makes them worse.

Woman with the flu
Image Source / Getty Images


Asthma symptoms can occur at any age, but they often develop in childhood. There are four main symptoms of asthma:

Symptoms may occur daily or only every once in a while. It's also common for symptoms to occur or get worse in the evening.

A chronic cough can also be a sign of poor asthma control.

Unlike asthma, the flu is contagious and caused by influenza viruses that can infect the nose, throat, and lungs. It can cause mild to severe illness, and sometimes can lead to complications and death in severe cases. Unlike a cold that comes on slowly, the flu typically has a sudden onset of symptoms, such as:

  • Fever
  • Chills
  • Cough
  • Sore throat
  • Runny or stuffy nose
  • Muscle or body aches
  • Headaches
  • Fatigue

Some people may also have vomiting and diarrhea with the flu, and these symptoms are more common in children than adults.

People with asthma may also experience asthma attacks, a sudden worsening of asthma symptoms, when they have the flu.

Most people recover from the flu within a few days to two weeks, but people with asthma have an increased risk of developing sinus, ear, or lung infections.


Factors and conditions that are considered high risk for serious complications from the flu include:

The combination of the flu and asthma, including bronchoconstriction and excess mucus production, can challenge even the best of immune systems, increasing the risk of pneumonia and hospitalization.

A study published in 2011 in the journal Pediatrics found that 32 percent of children hospitalized for seasonal flu over a six-year period had asthma. Children with asthma also represented 44 percent of all pediatric hospitalizations for H1N1 virus during the 2009 pandemic.

In addition to pneumonia, other serious complications that can occur with the flu include inflammation of the heart, brain, or muscle tissues, and multi-organ failure. The inflammatory responses can also make existing chronic conditions worse or contribute to sepsis, a life-threatening blood infection.

People with moderate to severe asthma may also be at higher risk of getting very sick from COVID-19, which can affect the lungs and cause an asthma attack.

Warning Signs

If you or your child have the flu and your symptoms improve but then return and worsen or you experience any of the following symptoms, seek emergency medical care:

  • Difficulty breathing/shortness of breath
  • Persistent pain or pressure in the chest or abdomen
  • Ribs pulling in with each breath
  • Persistent dizziness, confusion, inability to arouse
  • Not urinating
  • Severe muscle pain
  • Severe weakness or unsteadiness
  • Seizures
  • Bluish lips or face


The causes of asthma aren't fully understood, but it is believed to be a mixture of genetic predisposition and environmental factors.

You are at an increased risk of developing asthma or having asthma symptoms worsen if you have:

Asthma is often the result of a strong response of the immune system to a substance in the lungs. Although there is not a direct connection between contracting the flu and developing asthma, having viral respiratory infections and wheezing as a child is an overall risk factor for developing asthma or having it worsen.

There are two main types of flu viruses that routinely circulate each year: influenza A and influenza B. Influenza A is the type that is responsible for some pandemic viruses, such as H1N1 virus.

Flu viruses can spread by droplets released when people who are infected cough, sneeze or talk. These droplets can land in the mouths or noses of people who are nearby. It may also spread when someone touches a surface that has flu droplets on it and then touches their own mouth or nose.

Those who have the flu are most contagious in the first three to four days after their illness begins, but they can be contagious one day before symptoms develop and up to seven days after becoming sick. Young children and those with weakened immune systems may be able to infect others for even longer periods of time.

Flu can happen at any time, but is mostly a concern during flu season, starting as early as October and ending as late as May.

Causes of Asthma
  • Non-contagious chronic lung disease

  • Genetic predisposition and environmental factors increase risk of developing asthma

Causes of Flu
  • Contagious viral respiratory infections

  • Occurs after coming into contact or close proximity with a person infected with influenza or touching a contaminated surface


If you have asthma symptoms, your doctor will ask about your personal and family medical history, do a physical exam, and may have you do a series of pulmonary function test (PFT). There may also be additional tests, such as chest or sinus X-rays.

PFT tests measure your breathing and can help to confirm an asthma diagnosis. They are often done before and after giving you a bronchodilator medication to open the airways. These lung function tests may include:

  • Spirometry measures air volume of your exhales.
  • Peak Flow Meter measures how quickly your lungs expel air during a forceful exhalation after you fully inhale. This is a portable device that is often used at home to monitor asthma control and breathing status.
  • FeNO tests (fractional exhaled nitric oxide) measures the amount of nitric oxide in your breath, which can indicate a level of inflammation
  • Bronchoprovocation challenges are when your physician exposes you to asthma triggers such as cold air, exercise, histamine (can trigger allergic asthma), or methacholine (inhaled chemical that causes mild constriction of airways) to see if it induces asthma symptoms.

If you have flu symptoms, your doctor can run tests to check if it's the flu. This typically involves a swab of your nose or throat or collection of spit. There are rapid tests that can give results within 10 to 20 minutes, but these are not as reliable as viral cultures that are examined in a laboratory. Viral cultures involve sending a swab or sample to a specialized laboratory that analyzes it can often give results in one to three days.

Diagnosis of Asthma
  • Chronic symptoms (wheezing, chest tightness, shortness of breath, cough)

  • Consider personal and family history

  • Physical exam

  • Pulmonary function tests

Diagnosis of Flu
  • Sudden onset of symptoms (fever, cough, sore throat, runny or stuffy nose, body aches, headache, chills and/or fatigue)

  • Physical exam

  • Flu tests through nasal or throat swab or saliva sample


The overall treatment plan for asthma depends on the frequency and severity of symptoms, but it will include carrying short-acting beta-agonists (SABAs), known as rescue inhalers, that can address acute symptoms by widening airways quickly.

A rescue inhaler may be all that's needed for mild asthma or exercise-induced asthma that only happens during physical activity. Your physician will also help you develop an asthma action plan for recognizing asthma triggers and knowing what steps to take based on symptoms.

Most people with asthma are also prescribed one or more long-term controller medications that are taken daily to reduce inflammation and prevent symptoms over time. Inhaled corticosteroids, also called inhaled steroids, are a first-line treatment for asthma and are the most effective medications for long-term control of persistent asthma, which happens several times a week to up to multiple times a day.

Due to the high risk of serious flu complications, people with asthma should get the flu vaccine, unless there is a reason not to, such as a history of anaphylaxis (a serious allergic reaction) after a flu vaccine or Guillain Barre syndrome.

Each annual vaccine aims to prevent the four strains of influenza predicted to predominate that year.

Vaccination is relatively quick with few complications. If you have asthma and are concerned about getting a flu vaccine, there are some things to keep in mind:

  • Some physicians recommend the flu shot instead of the nasal spray for children and adults because of a concern that the nasal spray may have the potential to trigger an asthma attack. (Although, studies suggest that neither the flu shot or FluMist increase the risk of asthma exacerbations. )
  • While people were once told to avoid the flu vaccine if they had an egg allergy, but this is no longer the case. This is true no matter how severe your egg allergy may be. If in doubt, speak with your doctor.
  • Despite fears that the shot may give you the flu, the vaccines are made from materials which only resemble the virus and can't give anyone the flu. (Even with the live, weakened form of the virus in FluMist, the virus is scientifically unable to cause the flu.)

In addition to the flu shot, it recommended that you get a pneumonia vaccination if you haven't done so yet.

Treatment of Flu If You Have Asthma

If you have asthma and get flu symptoms, call your doctor as soon as symptoms arise. Your doctor may test you to confirm the flu and then give you a prescription for a type of flu treatment known as an antiviral. Antivirals work by suppressing viral activity which, in turn, alleviates the inflammation that can worsen asthma symptoms.

Typically, antivirals only decrease flu symptoms by about one day, but they may reduce the risk of complications, such as respiratory complications requiring antibiotics, ear infections in children, and hospitalization in adults.

Depending on the flu strains in your community, your doctor may recommend one or a combination of the following antiviral drugs:

People with asthma should not use that antiviral drug Relenza (zanamivir) because there is a risk it may cause wheezing in people with asthma or other lung conditions.

As a general rule, people with asthma who think they have the flu should consider antiviral treatment, ideally within 24 to 48 hours of the first appearance of symptoms. Although, there is still some potential benefits even if the antiviral is taken after two days from the start of symptoms.

Additionally, persons with asthma can opt for antiviral therapy if they have no symptoms but believe they were exposed to the virus. Called chemoprophylaxis, the therapy aims to avert infection by hitting it hard before symptoms arise. It should be started no later than 48 hours after exposure and will continue daily for 10 days to two weeks, depending on your doctor's recommendation.

Asthma Treatments
  • Fast-acting, short-term medications (rescue inhalers)

  • Long-term controller medications, such as inhaled corticosteroids

  • Asthma action plan

Flu Treatments
  • Flu shot as prevention

  • Antivirals

A Word From Verywell

Getting a flu shot, washing your hands thoroughly and regularly, and keeping your hands away from your face, are some of best things you can do to prevent the flu and other viral infections.

If you have asthma, it's also important to avoid asthma triggers, take your asthma medications as recommended, promptly refill supplies, and make sure that you have an updated asthma action plan. If your asthma symptoms worsen or are more frequent or if you get the flu, contact your physician promptly.

Was this page helpful?
Article Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Veerapandian R, Snyder JD, Samarasinghe AE. Influenza in asthmatics: for better or for worse? Front Immunol. 2018;9:1843. doi:10.3389/fimmu.2018.01843

  2. National Heart, Lung, and Blood Institute. Asthma. Updated May 21, 2020.

  3. Centers for Disease Control and Prevention. Flu symptoms & complications.

  4. Juhn YJ. Risks for infection in patients with asthma (or other atopic conditions): is asthma more than a chronic airway disease? J Allergy Clin Immunol. 2014;134(2):247-57. doi:10.1016/j.jaci.2014.04.024

  5. Centers for Disease Control and Prevention. People at high risk for flu complications. Updated September 9, 2020.

  6. Dawood FS, Kamimoto L, D'mello TA, et al. Children with asthma hospitalized with seasonal or pandemic influenza, 2003-2009. Pediatrics. 2011;128(1):e27-32. doi:10.1542/peds.2010-3343

  7. Kudo M, Ishigatsubo Y, Aoki I. Pathology of asthma. Front Microbiol. 2013;4:263. doi:10.3389/fmicb.2013.00263

  8. Centers for Disease Control and Prevention. How flu spreads. August 27, 2018.

  9. Centers for Disease Control and Prevention. Overview of influenza testing methods. Updated August 31, 2020.

  10. National Heart, Lung, and Blood Institute. Guidelines for the diagnosis and management of asthma (EPR-3). Updated September 2012.

  11. Chang K-H, Lyu R-K, Lin W-T, Huang Y-T, Lin H-S, Chang S-H. Gulllain-Barre Syndrome After Trivalent Influenza Vaccination in AdultsFrontiers in Neurology. 2019;10. doi:10.3389/fneur.2019.00768

  12. Vasileiou E, Sheikh A, Butler C. Effectiveness of Influenza Vaccines in Asthma: A Systematic Review and Meta-AnalysisClin Infect Dis. 2017;65(8):1388–1395. doi:10.1093/cid/cix524

  13. Grohskopf LA, Sokolow LZ, Broder KR, Walter EB, Fry AM, Jernigan DB. Prevention and control of seasonal influenza with vaccines: recommendations of the advisory committee on immunization practices-United States, 2018-19 influenza season. MMWR Recomm Rep. 2018;67(3):1-20. doi:10.15585/mmwr.rr6703a1

  14. Centers for Disease Control and Prevention. Misconceptions about seasonal flu and flu vaccines.

  15. Centers for Disease Control and Prevention. What you should know about flu antiviral drugs. Updated September 3, 2020.

  16. Centers for Disease Control and Prevention. Flu & people with asthma. Updated August 31, 2020.