A cough may linger following a cold or the flu. After ruling out other issues, the doctor may diagnose a “post-viral cough.” Experts are unsure exactly why this happens, but there are a few possible causes.

Keep reading for more information about a cough that continues after recovery from a viral infection such as the flu. We look into the causes, treatments, and when to see a doctor.

What is a post-viral cough?

A post-viral cough may follow a respiratory infection.
A cough may linger after a person has recovered from a viral infection, and the medical term for this issue is a post-viral cough.

According to a 2017 review, a post-viral cough that continues after recovering from a cold or flu typically disappears on its own after a few days. If it continues for 3 weeks or more, healthcare professionals consider the post-viral cough to be persistent.

A 2016 review reports that post-viral coughs sometimes last 3–8 weeks.

Causes
A cough may persist after recovery from the flu for a few different reasons.

Respiratory infections
Beyond the flu, the following infections can lead to a post-viral cough:

• bronchitis
• the common cold
• croup
• pneumonia
• pharyngitis
• bronchiolitis
• According to a 2020 review, a post-viral cough can be caused by increased sensitivity of cough receptors in the body or temporary bronchial hyper-responsiveness.

Older research, from 2006, suggests that coughs tend to persist after recovery from infection due to extensive inflammation in the lining of the airways.

Also, the researchers observe, if the cough originates in the lower airways, excess mucus production may be responsible.

Other underlying medical conditions
Meanwhile, separate health issues can cause a cough to linger after a person has recovered from an infection.

In this case, the cough is linked to the underlying condition, not the infection. In other words, it is not post-viral.

Asthma
Asthma causes the airways to become swollen and sensitive.

If a person with asthma develops the flu, which then causes additional inflammation in the airways, this can trigger asthma attacks or worsen asthma symptoms.

People may not be aware that they have asthma. Because the symptoms can be very mild, it may be easy to mistake them for persistent effects of a respiratory infection, for example.

Other symptoms of asthma include:

• difficulty breathing
• chest tightness
• wheezing
• shortness of breath
• Laryngeal pharyngeal reflux
• Laryngeal pharyngeal reflux (LPR) involves acid from the stomach traveling up through the esophagus and into the throat.

The acid tends to irritate and inflame the vocal cords, and a cough is a common symptom of this issue, according to the International Foundation for Gastrointestinal Disorders.

It may be difficult for someone with this reflux to distinguish the cause of their cough, as LPR often begins after an upper respiratory illness, the foundation reports.

Other symptoms of LPR may include:

• frequent throat clearing
• hoarseness
• a feeling that something is stuck in the throat
• Obstructive sleep apnea
• According to 2015 research, obstructive sleep apnea (OSA) can cause a chronic cough. The connection remains unclear, but it may involve OSA causing:

airway inflammation
gastroesophageal reflux disease, or GERD
cough reflex sensitivity
Symptoms of OSA include:

• snoring
• daytime fatigue
• pauses in breathing
• memory and concentration difficulties
• irritability
• headaches
• dry mouth
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Diagnosis
If a person is experiencing a persistent cough following a viral infection, they should talk to a doctor.

The doctor may perform a physical examination and ask about other symptoms. Let the doctor know about the recent infection.

They may order an X-ray of the chest, to look for signs of any underlying condition that could be causing the cough.

To check for any current infection, the doctor may run tests on a sample of sputum, the thick substance that the lungs create during an upper respiratory infection.

If the doctor has ruled out other possible underlying causes, they may diagnose post-viral cough. This issue may last 3–8 weeks.

Treatment
To help ease a cough at home, a person can try:

• breathing in steam from a hot shower or bath to open the airways
• drinking warm broths and teas
• avoiding irritants such as pollen, smoke, and dust
• using a humidifier
• If these techniques do not work, a doctor may recommend over-the-counter or prescription medications.

Some that can relieve a post-viral cough include:

• antihistamines
• decongestants
• cough suppressants
• ipratropium, a prescription inhaled medication that prevents mucus production and opens the airways
• oral or inhaled corticosteroids, prescription medications that can reduce inflammation
• As always, it is important to review any current medications with the doctor.

When to see a doctor
A post-viral cough can clear within a few days or weeks without treatment. However, if there is ever any doubt about the cause of a cough, talk to a healthcare provider.

Also, it is important to let the doctor know if any treatments are not working. They may be able to recommend other options.

If a post-viral cough lasts longer than 8 weeks, talk to the doctor, as there may be a different underlying cause.

Summary
A post-viral cough is one that lingers after a person has recovered from a viral infection. It may last 3–8 weeks.

These coughs typically clear up on their own, but treatments and home care techniques can help

In some cases, an underlying health issue causes a chronic cough that may resemble a post-viral cough. Viral infections can exacerbate the issue.

Talk to a doctor if a cough lasts longer than 8 weeks, if the cause of a cough is unclear, or if a persistent cough is causing any concern.