How Colds and Asthma Are Linked

If you have asthma, you may be more likely to catch the common cold, and the cold or other viral infections can make your asthma flare up.

Asthma and colds both involve airway inflammation. When you have both, it can make asthma symptoms harder to control. An otherwise mild respiratory infection can turn into a serious medical event.

This article explains why viral infections like the cold can trigger asthma symptoms, how these episodes are diagnosed and treated, and how you can lower your risk of having both conditions at the same time.

How Asthma Makes You More Susceptible to Colds

Poorly controlled asthma can cause high levels of inflammation that permanently damage the lining of your airways. Over time, this can make the airways thicken and lose flexibility.

That appears to raise your risk of respiratory infections. Scientists aren't entirely sure why.

Some studies suggest it's due to damage to cells called epithelial cells, which line your airways.

During an immune-system response, epithelial cells produce an important substance called cytokines, which play a key role in killing viruses in your body.

Genetics may also play a part. Research suggests that some people are genetically predisposed to catch colds more often, get sicker with them, develop more inflammation, and have worsening asthma.

Inhaled steroids are sometimes used to manage asthma. They can suppress your immune system and raise the risk of respiratory illnesses like colds, the flu (influenza), and pneumonia.

How Colds Worsen Asthma

When asthma is caused by a virus, it's called viral-induced asthma. It's common, affecting roughly 85% of children and 50% of adults with asthma. It is not the same as cold-induced asthma, which is when breathing cold air triggers an asthma attack.

A garden-variety cold can be caused by any one of over 200 viral strains, any one of which has the potential to trigger asthma symptoms in those with the condition. The most common ones are:

• Rhinoviruses
• Coronaviruses, including the one that causes COVID-19
• Influenza viruses
• Adenoviruses
• Respiratory syncytial virus (RSV)

When you have a respiratory infection, your immune system responds by releasing cytokines. Many cytokines trigger airway hyper-responsiveness and bronchoconstriction (throat tightening) in people with asthma.

The Role of Allergies

If you have allergies or allergic asthma, there's yet another reason the immune response to a cold can make asthma worse.

Cytokines draw white blood cells to the site of the infection. Among them are eosinophils, which are tied to allergic asthma and can increase inflammation.

So, now you have multiple sources of airway inflammation—a cold, asthma, and allergies. This may explain why certain people are more prone to viral-induced asthma than others.

Symptoms of Viral-Induced Asthma

Colds affect every part of the upper respiratory tract, from the nasal passages to the larynx (voice box). Asthma affects every part of the lower respiratory tract from the larynx to the lungs.

Each has its own symptoms, so the difference between a cold and asthma is relatively easy to identify when only one is present.

There is some overlap, such as coughing and difficulty breathing, but cold symptoms generally affect the nose and throat while asthma symptoms come more from the chest.

Timing of Symptoms

With viral-induced asthma, the symptoms of a cold typically come before an asthma attack. At that point, both the upper and lower respiratory tract become affected.

This means the sneezing, coughing, headache, and nasal congestion of a cold triggers asthma symptoms (wheezing, shortness of breath, and chest pain). If a cold develops rapidly, the cascade of symptoms may occur all at once.

With viral-induced asthma, you may have symptoms that are uncommon in either disease, including high fever and chills. This typically happens when there's a secondary infection of the lungs, such as bacterial pneumonia.

Diagnosis

The overlap of symptoms in people with viral-induced asthma can make diagnosis difficult.

Healthcare providers easily recognize classic cold symptoms. But asthma-related wheezing, shortness of breath, and chest pain can be caused by other diseases, such as severe bronchitis or pneumonia.

Diagnosing viral-induced asthma requires a thorough review of your symptoms and medical history along with a physical exam and other diagnostic tests.

Diagnostic Work-Up

A diagnosis of viral-induced asthma typically requires some detective work. As part of the work-up, the healthcare provider will want to know:

• Current symptoms, what happened before them, and which came first
• Your history of respiratory infections
• Your family history of chronic respiratory illnesses
• Your smoking history
• Any chronic illnesses you have, such as chronic obstructive pulmonary disease COPD or congestive heart failure

A physical exam includes an evaluation of your breathing with a stethoscope. Apart from wheezing, other breath sounds may add to evidence for the cause of your condition. Wheezing is considered one of the defining features of asthma. Any accompanying sounds may suggest which type of virus is involved.

Lab and Imaging Tests

If your symptoms are severe and your healthcare provider detects abnormal breathing sounds, they may order blood tests to check for viral pneumonia, RSV, influenza, or COVID-19.

Common tests include:

• Throat swab or sputum culture, if a bacterial infection is suspected
• Chest X-ray or computed tomography (CT) to check for pneumonia or lung abnormalities
• Pulse oximetry or an arterial blood gas (ABG) test to see if blood oxygen levels are low
• Nasal swab tests for COVID-19

Blood tests for rhinovirus or adenovirus are also available, but because treatments aren't available for them, the tests are used less often.

Pulmonary function tests (PFTs) can evaluate how well your lungs are functioning during and after an acute attack. If tests show both a respiratory infection and decreased lung function, it's a strong indicator that you have viral-induced asthma, especially if your asthma is well-controlled.

Allergen testing may be useful in diagnosing allergic asthma, but it does not necessarily exclude viral-induced asthma as a cause. Given how common viral-induced asthma is, some findings warrant treatment even if the specific virus isn't identified.

How Do You Treat a Cold With Asthma?

Asthma medications will never fully prevent or relieve asthma symptoms induced by a cold or other respiratory illness. That's because they produce different kinds of cytokines, and asthma drugs only treat some of them.

Breathing difficulties may persist as the inflammation in both the upper and lower respiratory tracts feed on each other. Symptoms will continue until the viral infection is resolved.

This is especially true when eosinophils are produced in excess. This can lead to a condition known as eosinophilia, in which the eosinophil build-up causes inflammatory damage to the airways. It's this sort of damage that can increase the risk of severe illness, including pneumonia, in people with viral-induced asthma.

Medications

If a cold is a trigger for an attack, the resolution of the infection (which usually happens within two weeks) will usually improve breathing problems as well.

Still, the standard treatment of a cold or flu should be accompanied by the appropriate use of asthma medications. This may include the increased use of a short-acting beta-agonist (also known as a rescue inhaler).

According to the National Heart, Lung, and Blood Institute, a short-acting beta-agonist like albuterol can be used every four to six hours during a cold to reduce the risk of an asthma attack. Check with your healthcare provider to make sure this is safe for you.

The use of antihistamines for viral-induced asthma is uncommon unless you have allergic asthma. Allergy medications relieve nasal congestion from a cold, but they tend to be less useful in treating viral-induced asthma as they have no effect on the virus itself.

Prevention

One of the best ways to avoid viral-induced asthma attacks is to avoid colds and other viral illness.

This is often easier said than done, particularly during cold and flu season or 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) recommends the following measures for preventing viral illnesses:

• Stay away from 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.

You may also want to wear a mask in public during cold and flu season, allergy season, or when COVID-19 cases are high in your area.

To further reduce the risk of viral-induced asthma, adhere to your daily asthma medications, taking them as prescribed and on schedule. If you have a history of severe viral-induced attacks, ask your healthcare provider if a short course of oral corticosteroids is reasonable.

You should also steer clear of secondhand smoke and other asthma triggers until the cold is fully resolved. If you are a smoker and cannot quit, ask your healthcare provider about smoking cessation aids (including nicotine patches and oral medications) to help you stop.

Preventing Asthma Attacks When You Have a Cold

The key to preventing asthma attacks during viral illnesses is having well-controlled asthma. If you use a rescue inhaler more than twice a week, talk to your healthcare provider about how to improve control.

Finding the right combination of asthma controller medications can significantly reduce your risk of an attack.

If you have a history of severe viral-induced asthma, speak with your healthcare provider about taking oral corticosteroids at the start of a cold. There's some evidence they can help, especially in people who need emergency care or hospitalization after a severe attack.

Summary

It's common for asthma get worse with a cold, or to have more severe cold symptoms due to your asthma. You may even have asthma only when you have a respiratory infection. Allergies and allergic asthma can exacerbate the problem, as well.

Having a cold and asthma together can make both of them harder to manage. Medications for both problems can help.

Prevention is important, so be sure to take your asthma medications as prescribed. You'll also want to avoid getting sick, so practice social distancing, wash your hands often, disinfect high-touch items and surfaces, and consider wearing a mask.

A Word From Verywell

If you find that a cold or flu triggers an asthma attack, let your healthcare provider know. This occurs more often than you might think, and it may mean you need more aggressive asthma treatment That's especially true if you're prone to respiratory infections.