What to Do If a Cold Makes Your Asthma Worse

Woman using an aerosol inhaler to improve breathing.

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Asthma is associated with inflammation of the lower airways of the lung, including the trachea (windpipe), bronchi, and bronchioles. The common cold is a viral infection that affects the upper airways, including the nose and throat. Because of the close proximity of these airways, colds can often impact asthma and vice versa.

There are other factors that influence how colds and asthma interact and may alter how the diseases are diagnosed and treated. Having a cold and asthma together can make asthma symptoms harder to control and turn an otherwise mild respiratory infection into a serious medical event.

When a cold triggers an asthma attack, it is typically referred to as virus-induced asthma. In some cases, a cold may "unmask" asthma symptoms and require different treatment approaches to reduce the risk of a severe asthma event.

Virus-induced asthma should not be confused with cold-induced asthma in which an attack is triggered by inhaling cold air (often during exercise or physical activity).


Colds and allergy symptoms differ by the air passages affected. In the simplest terms, colds affect every part of the respiratory tract from the voice box up, while asthma affects everything from below the voice box to the lungs. These differences make the symptoms of each disease distinctive and relatively easy to recognize.

A number of these symptoms do overlap, however, including cough, throat pain, and breathing problems. Even so, the underlying causes for these symptoms differ, making it relatively easy to distinguish whether they are coming from the chest or from the nose and throat.

Comparative Symptoms of Colds and Asthma
  Common Cold  Asthma Attacks
Breathing problems Common, usually mild with nasal and sinus congestion Common, usually severe with shortness of breath, wheezing, and difficulty breathing
Cough Common, sometimes with phlegm Common, often dry (hacking) but occasionally wet (with phlegm)
Nasal problems Common, including runny nose, sneezing, post-nasal drip, and congestion No
Throat pain Common, usually with mild sore throat Common, including throat tightness, hoarseness, or irritation 
Fever Common, usually mild Uncommon
Headache Common Uncommon
Body aches Common, usually mild muscle and joint aches No
Chest pain Occasional, mostly due to prolonged coughing Common, including chest pain and tightness

The same may not be said if a cold and asthma co-occur. With virus-induced asthma, the symptoms of a cold (such as fever, cough, and nasal congestion) will typically precede the asthma attack, even if the "domino effect" occurs in rapid succession.

In other cases, cold and asthma symptoms may seem to develop all at once, affecting the upper and lower respiratory tracts in tandem. In some people, the appearance of a cold virus triggers the release of inflammatory compounds (called cytokines) that not only fight the infection but end up causing a hyperresponsive reaction in the airways.

Because the incubation period of a cold virus is between 24 and 72 hours, the rapid buildup of these compounds can trigger an asthma attack at the same time⁠—and even before⁠—cold symptoms are recognized. This can make virus-induced asthma attacks all the more difficult to diagnose and treat.


There is not one cold virus or one type of asthma. The common cold is caused by any one of over 200 viral strains, the most common on which are rhinoviruses followed coronaviruses, influenza viruses, adenoviruses, and respiratory syncytial viruses (RSV).

Similarly, there are different types of asthma, each of which are triggered by different substances or events. These include allergic asthma, non-allergic asthma, cough variant asthma (CVA), exercise-induced asthma, and asthma-COPD overlap syndrome (ACOS), among others.

The common denominator for all forms of asthma is an abnormal immune response wherein the body releases immune cells and chemicals that cause the narrowing of airways and the excess production of mucus.

However, the types of cells and chemicals the body secretes can vary by the substance or event that triggers the immune response. These include antibodies such as immunoglobulin E (IgE), defensive white blood cells such as macrophages, neutrophils, and T-cell lymphocytes, and pro-inflammatory compounds such as cytokines, histamine, and leukotriene.

Viral Triggers

With virus-induced asthma, researchers concluded back in 2005 that a specific type of cytokine, called interleukin 10 (IL-10), functioned as the trigger for airway hyperresponsiveness. This was an entirely different chemical than the ones attributed to allergic asthma (primarily IgE).

In recent years, scientists have identified other interleukin types linked to the specific cold viruses, such as rhinoviruses and interleukin 3 or adenoviruses and interleukin 4, 5, and 11. How these compounds trigger an attack is not entirely clear, but it is known that interleukins activate white blood cells known as eosinophils that help regulate inflammation in the body.

Risk Factors

Why certain people are hypersensitive to these viral-induced cytokines remains poorly understood. Genetics is believed to play a significant role given that identical twins have a one-in-four chance of both having asthma. While no less than 100 different gene mutations are believed to be linked to asthma, it is unclear which ones are responsible for virus-induced asthma.

What scientists do know is that certain viruses are more likely to induce asthma than others. Rhinoviruses are by far the most common cause both in adults and children (in part because they are the predominant cause of colds). Children with asthma are especially vulnerable to influenza viruses, while younger children and infants are at risk of severe asthma when exposed to RSV.

Research has shown that virus-induced asthma is a relatively common occurrence both in adults and children.

According to a 2014 review in the European Respiratory Journal, no less than 77% of children and 80% of adults with asthma show evidence of a viral infection at the time of an asthma attack.


The overlap of symptoms in people with virus-induced asthma can make diagnoses difficult. For the most part, the appearance of classic cold symptoms is easily recognized by physicians. However, when accompanied by wheezing, shortness of breath, and difficulty breathing, the combination of symptoms can easily be confused with other diseases, including severe bronchitis or pneumonia.

This is especially true for people in whom asthma remains undiagnosed and may only develop in the presence of an infection. Virus-induced asthma may also be missed in younger children with RSV or people with flu as breathing restriction and wheezing are common with both.

Moreover, if there is a respiratory condition such as chronic obstructive pulmonary disease (COPD), it may be presumed that a cold simply worsened the symptoms, leaving asthma unexplored as a cause.

The diagnosis of virus-induced asthma, therefore, requires a comprehensive review of your current symptoms and medical history along with a thorough physical exam and other diagnostic tests.

Common Colds

  • Commonly diagnosed by symptoms and physical exam

  • A nasal swab may be used in children under 2, the elderly, and those with weakened immune systems to confirm RSV infection

  • Chest X-ray and other tests may be used to exclude other causes


  • Pulmonary function tests (PFTs), including spirometry and exhaled nitric oxide

  • Mannitol or methacholine challenge tests if PFTs are less than conclusive

  • Allergen testing to rule out allergic asthma

Diagnostic Work-Up

Diagnosing virus-induced asthma typically requires some detective work. As part of the diagnostic work-up, the doctor will want to know:

  • Which symptoms you experienced or are experiencing
  • The order of appearance of symptoms (i.e., which came first)
  • How quickly symptoms developed and how long they lasted
  • Past respiratory illnesses you've had
  • Your family history of respiratory disease
  • Chronic illnesses you may have (like COPD or congestive heart failure)
  • Your smoking history

In addition, the doctor will take into consideration the season (since rhinovirus outbreaks tend to occur in the fall with a second surge in spring) and the age of the patient (since certain viruses, like RSV, are more common in children).

The physical exam would include an evaluation of breathing sounds to detect crackles (rales), vibrations (stridor), ratting (rhonchi), or wheezing, each of which can point the doctor in the direction of the likely cause. With asthma, wheezing is considered one of the defining features of the disease

While some doctors may discount the symptoms as those of a severe cold or flu and prescribe standard treatments, severe wheezing is rarely left unexplored.

One of the central clues that asthma is involved is the episodic nature of the breathing restrictions, which tend to come on fast and resolve spontaneously.

Lab and Imaging Tests

If abnormal breathing sounds are heard, the doctor will likely order blood tests to investigate whether viral pneumonia, RSV, or influenza is the cause. If a bacterial infection is suspected, a throat swab or sputum culture may be performed.

The doctor will likely order a chest X-ray as well or, in severe cases, a computed tomography (CT) scan. Episodes requiring emergency care or hospitalization will typically involve tests to measure blood oxygen levels, including pulse oximetry or an arterial blood gas (ABG) test.

As extensive as these evaluations may be, they can help exclude other causes for wheezing and shortness of breath—including allergy, COPD, pneumonia, and bronchitis⁠—and help direct the doctor toward asthma as a likely cause.

Asthma-Specific Tests

If asthma is suspected, the doctor will order pulmonary function tests (PFTs) once the acute symptoms have passed and the underlying infection is resolved. Among the standard tests used to diagnose asthma:

  • Spirometry is a simple breathing test that measures the volume and velocity of air you can blow air out of your lungs. If asthma is suspected, the first round of testing would be performed without an inhaled bronchodilator (used to open airways) and the second round with. An improvement in the second round may be strongly indicative of asthma.
  • Exhaled nitric oxide tests measure the amount of nitric oxide you breathe out. It involves a small, handheld machine into which you breathe for around 10 seconds. Nitric oxide values of 35 parts per billion (ppm) or more in children and 50 ppm or more in adults may be suggestive of asthma.
  • Challenge tests may be used if the results of the other tests are less than conclusive. They involve the inhalation of a substance (methacholine or mannitol) to see if it induces spasms and narrowing of the airways.

An allergen test may also be performed to determine if your symptoms are related to allergy. It may involve a blood test or skin prick test to detect IgE reactions to common allergens. Skin tests tend to be quicker (returning results within an hour), but blood tests tend to be more accurate.

There are no specific protocols for diagnosing virus-induced asthma. With that said, a negative allergen test accompanied by positive PFTs for asthma may be suggestive of the condition.


Having virus-induced asthma doesn't necessarily alter how a cold is treated or how asthma attacks are managed. If a cold or flu is a trigger for an attack, the resolution of the infection will usually improve breathing problems as well.

Cold Treatment

  • Typically recovers on its own within two weeks

  • Symptoms may be managed with decongestants, cough formula, antihistamine, and nonsteroidal anti-inflammatory drugs

  • Nasal washing may help clear mucus build-up

  • Flu may be shortened with the early use of antiviral drugs like Tamiflu (oseltamivir) and plenty of bed rest

Asthma Treatment

  • Inhaled corticosteroids

  • Inhaled long-acting beta-agonists like salmeterol

  • Inhaled short-acting beta-agonists like albuterol

  • Inhaled anticholinergics like Spiriva (tiotropium bromide)

  • Injectable or intravenous biologics like Dupixent (dupilumab)

  • Oral leukotriene modifiers like Singulair (montelukast)

  • Oral corticosteroids

If virus-induced asthma occurs, the appropriate treatment of a cold or flu should be accompanied by the appropriate use of asthma medications to help relieve asthma symptoms. This includes the increased use of short-acting "rescue" inhalers.

According to the National Heart, Lung, and Blood Institute, a short-acting beta-agonist like albuterol can be used safely every 4 to 6 hours during a cold and may help reduce the risk of an asthma attack.

Using these rescue inhalers for more than 4 to 6 hours should be avoided unless your doctor tells you otherwise. If cold and asthma symptoms require you to use rescue inhalers more frequently than every 6 weeks, you probably need to step up your asthma treatment. Speak to your doctor.

One of the areas in which treatment plans can vary is in the use of antihistamines. Though antihistamines can provide relief of nasal decongestion caused by a cold, they tend to be of less value in treating virus-induced asthma since it is not associated with allergy. This includes nasal and oral antihistamines as well as nasal steroids and allergy shots commonly used by people with allergic asthma.

If you have a history of severe asthma with a cold, talk with your doctor about taking oral corticosteroids at the start of a cold, especially if past attacks were severe or required hospitalization.


Clearly, one of the best ways to avoid asthma attacks triggered by colds is to avoid colds in the first place. This is often easier said than done, particularly during cold and flu season and in families with young children. Cold viruses are easily passed by sneezing and cough or by touching surfaces contaminated with germs.

The Centers for Disease Control and Prevention (CDC) recommend the following measures to avoid getting a cold:

  • Avoid people who are sick.
  • Wash your hands frequently with soap and water for at least 20 seconds.
  • Avoid touching your face, nose, or mouth with unwashed hands.
  • Disinfect frequently touched surfaces and items, including counters and toys.

There are currently no vaccines to prevent a cold, but annual flu shots can help reduce your risk of influenza and, with it, the risk of an asthma attack.

A Word From Verywell

If you find that a bout of cold triggers an asthma attack, let your doctor know. This occurs more frequently than many people think and may indicate the need for more aggressive treatment, especially if you are prone to respiratory infections.

If you experience severe but limited episodes of wheezing and shortness of breath whenever you get a cold but have not been diagnosed with asthma, ask your doctor for a referral to a lung specialist called a pulmonologist for further evaluation. Pulmonary function tests are safe and relatively easy to perform and may help determine if asthma is the cause of your symptoms.

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