Yes. Viral infections can trigger asthma symptoms or an asthma attack, especially infections that affect the airways, such as the common cold, flu, COVID-19, and RSV. During an infection, already sensitive airways may become more inflamed and narrow, making breathing harder. A virus does not cause every episode of asthma symptoms, but it is a common trigger. Symptoms can continue after other cold symptoms start to improve.
A respiratory infection can affect breathing even when the infection itself seems mild. For someone with asthma, a familiar cold may be followed by more coughing, wheezing, chest tightness, or shortness of breath. These changes are often described as an asthma flare-up. Understanding the connection between viral infections and asthma can help people recognize changes in their breathing, follow their prescribed asthma plan, and know when to seek medical care.
How can a viral infection trigger asthma symptoms?
Asthma affects the airways, which are the tubes that carry air into and out of the lungs. In people with asthma, these airways can become inflamed and overly sensitive. A respiratory virus may add to that inflammation, causing the airways to narrow and making it harder for air to move freely. The resulting symptoms may be more noticeable than the usual symptoms of a cold.
The Centers for Disease Control and Prevention (CDC) explains that influenza can cause further inflammation in the airways and lungs, trigger asthma attacks, and worsen existing asthma symptoms. This helps explain why respiratory infections can affect breathing beyond the usual effects of a cough, sore throat, or runny nose.
Which viral infections can make asthma worse?
Several viruses that affect the respiratory tract can trigger asthma symptoms. The infection may begin in the nose and throat, but its effects can also involve the lower airways. Common examples include:
- Rhinovirus: This virus is a leading cause of the common cold and a common viral trigger for asthma attacks.
- Influenza: The flu can worsen asthma symptoms and increase the risk of respiratory complications.
- Respiratory syncytial virus (RSV): This virus often causes cold-like symptoms but can also trigger asthma attacks.
- COVID-19: Infection with the virus that causes COVID-19 can worsen asthma or trigger an asthma attack.
The CDC's information on rhinoviruses identifies rhinoviruses as a common viral trigger for asthma attacks. However, not every infection leads to a flare-up, and the effect can differ from one illness to another.
The CDC's guidance on respiratory infections and asthma also explains that flu, COVID-19, and RSV can be more serious for people with asthma because these infections may lead to asthma attacks and complications such as pneumonia.
Does a viral infection cause asthma or only trigger it?
These are two different questions. In a person who already has asthma, a viral infection can trigger symptoms or make the condition temporarily harder to control. This is called an asthma flare-up or exacerbation. It does not necessarily mean that the underlying condition has permanently worsened.
Viral infections affecting the airways may also be one factor associated with the development of asthma, particularly when considering early-life respiratory infections. However, asthma does not have one single cause. The National Heart, Lung, and Blood Institute (NHLBI) explains that several factors may contribute to asthma development, including environmental exposures, family history, and viral infections that affect breathing.
Having a cold followed by wheezing does not automatically establish that someone has asthma. Viral illnesses can cause coughing and breathing symptoms for other reasons. When symptoms are new, keep returning, or continue after the infection has passed, a healthcare professional can assess the pattern and determine whether further evaluation is appropriate.
What symptoms may appear during a virus-related asthma flare-up?
During a respiratory infection, asthma symptoms may become more frequent or more noticeable than usual. Some people experience changes in breathing before, during, or after their other infection symptoms. Examples include:
- A cough that becomes more persistent, especially at night or early in the morning.
- Wheezing, which may sound like a whistle when breathing out.
- Shortness of breath during everyday activities or while resting.
- A feeling of tightness or pressure in the chest.
- Needing prescribed reliever medicine more often than usual.
- Waking during the night because of coughing or breathing discomfort.
These symptoms can be associated with an asthma flare-up, but they can also occur with other respiratory illnesses. The pattern matters: worsening asthma symptoms often appear alongside an infection or become more apparent as the illness progresses. A clinician considers the person's medical history, usual asthma symptoms, examination findings, and response to prescribed treatment when assessing what may be happening.
How long can asthma symptoms last after a viral infection?
Asthma symptoms may continue even after a runny nose, sore throat, or fever begins to improve. The duration depends on the infection and how the airways respond. Some flare-ups settle relatively quickly, while others take longer to improve and may require medical review or changes to treatment under professional guidance.
Mayo Clinic's guidance on asthma attacks caused by colds or flu notes that symptoms associated with respiratory infections may last from several days to weeks. A cough that persists, repeated night-time symptoms, or ongoing breathing difficulty should not automatically be attributed to a lingering virus, particularly when symptoms interfere with sleep or daily activities.
What should you do if a virus makes your asthma worse?
The most useful approach is to follow an established asthma management plan rather than waiting for the infection to disappear. The appropriate response depends on the person's prescribed medicines, usual symptoms, and the instructions provided by their healthcare professional.
- Follow your asthma action plan. Use prescribed medicines as directed and follow the plan's instructions for worsening symptoms.
- Continue your regular treatment. Do not stop prescribed preventer inhalers or change medicine doses on your own because you have a cold or flu.
- Check how your breathing is changing. Pay attention to symptoms that are more frequent than usual, waking at night, difficulty with routine activities, or increased reliance on reliever medicine.
- Contact a healthcare professional when symptoms worsen. Ask for advice if your usual treatment is not working as expected, symptoms persist, or you are unsure how to follow your action plan.
- Ask promptly about flu treatment if relevant. People with asthma who develop flu symptoms should contact their healthcare professional promptly because antiviral treatment may be appropriate.
Cold and flu medicines should also be chosen carefully. Some products contain several active ingredients, and not every medicine is suitable for every person. Check with a healthcare professional or pharmacist before using a new product, particularly if you have other medical conditions or take regular medication.
When is breathing difficulty an emergency?
A respiratory infection can occasionally be followed by a serious asthma attack. Seek emergency medical help if breathing becomes very difficult, symptoms rapidly worsen, or prescribed reliever treatment does not help as directed in your asthma action plan. Difficulty speaking because of breathlessness or becoming too breathless to perform basic activities also requires urgent attention.
Do not wait for a fever or other infection symptoms to resolve before seeking help for serious breathing problems. The National Health Service (NHS) asthma guidance advises urgent emergency assistance when an asthma attack is worsening or does not improve after the recommended reliever treatment. Follow your local emergency procedures and your personal action plan.
Can viral infections and asthma flare-ups be prevented?
Not every respiratory infection can be avoided, but reducing exposure to viruses and keeping asthma treatment up to date may lower the chance of infection-related problems. Prevention is especially important for people whose previous respiratory illnesses have caused significant breathing difficulties.
- Keep vaccinations up to date. Discuss recommended flu, COVID-19, and other respiratory-virus vaccines with a healthcare professional. Eligibility and recommendations vary by vaccine, age, and individual circumstances.
- Practice good hand hygiene. Wash your hands regularly and avoid touching your eyes, nose, and mouth with unwashed hands.
- Reduce exposure to respiratory infections. Avoid close contact with people who are sick when possible, improve indoor ventilation, and consider a well-fitting mask in crowded indoor settings.
- Keep your asthma plan current. Review inhaler technique, medicine instructions, and the steps to follow when symptoms increase with your healthcare professional.
Keeping asthma well managed is important even when symptoms are absent. Continue prescribed treatment and seek advice about preventive measures suited to your age, medical history, and local vaccination recommendations. These steps cannot guarantee that an infection will not cause a flare-up, but they can help reduce preventable risks and prepare you to respond early when symptoms change.
What is the main takeaway about viruses and asthma?
Viral infections are common triggers of asthma flare-ups. Colds, flu, COVID-19, and RSV can increase airway inflammation and make coughing, wheezing, chest tightness, or shortness of breath worse. Symptoms may continue after other signs of infection improve, so changes in breathing deserve attention. Following an asthma action plan, continuing prescribed treatment, keeping recommended vaccinations up to date, and seeking timely medical help when symptoms worsen can help people manage infection-related asthma problems.