Possible causes and evaluation of persistent cough

A persistent or chronic cough is a common symptom, and there are many possible causes. The annoying effects of coughing, such as insomnia, sore chest muscles, and leaking urine, can affect your quality of life and interfere with your daily activities.

If you have a lingering cough, you might also wonder if it’s worse than a cold or allergies. What does it mean if your cough won’t go away?


Persistent cough is defined as a cough that lasts for a period of time Eight weeks or more. It may be a dry cough, or you may cough up mucus (phlegm) along with expectoration.

A persistent cough can also be called “chronic,” “lingering,” or “nagging.”

A subacute cough is one that lasts three to eight weeks, while an acute cough (such as that caused by the common cold) lasts less than three weeks

possible reason

There are many possible causes of a persistent cough. Most of the time, treatment can help relieve your cough so you can sleep better, feel more energetic, and stop the chest pain caused by your cough.

While the most common cause is usually not serious, sometimes a cough can have a serious cause, such as lung cancer.

Most common cause in adults

The most common causes of cough in children and adults are not the same, and the evaluation and treatment of persistent cough will depend on a person’s age, other relevant symptoms, and past medical history.

post-nasal drip

Postnasal drip from hay fever (allergic rhinitis), sinus infections, nasal polyps, or other medical conditions is the most common cause of chronic cough. These are called upper respiratory diseases.

Seasonal allergic rhinitis comes and goes in a seasonal pattern, and there may not be a consistent pattern of allergy causes throughout the year.


Asthma can cause persistent and intermittent coughing and often other symptoms such as wheezing and shortness of breath. When asthma attacks, these symptoms usually come together.

Cough variant asthma is a type of asthma in which cough is the most obvious symptom.

acid reflux

Gastroesophageal reflux disease (GERD) can cause chronic cough. Some people have no typical symptoms such as heartburn, and the only symptom may be a chronic cough.

Cough caused by GERD usually worsens after lying in bed at night.

Eosinophilic bronchitis

Although many people have not heard of eosinophilic bronchitis, it is one of the top four causes of chronic cough in adults. Eosinophilic bronchitis is caused by an immune cell response.

Because lung function tests are usually normal, diagnosis can be a little challenging. This condition usually responds to inhaled steroids.

Most common cause in children

Causes of chronic cough in young children may include:

  • asthma
  • Prolonged episodes of bacterial bronchitis
  • Upper respiratory tract cough syndrome, a post-infection cough that sometimes persists for weeks after an upper respiratory tract infection

Other common reasons

Less common but not uncommon causes of chronic cough include:

  • Smoker’s cough is a common cause of persistent cough.
  • Worldwide, tuberculosis is a common cause of chronic cough.
  • ACE inhibitors can cause a dry cough. Examples of these drugs include Vasotec (enalapril) and Zestril (lisinopril).
  • Chronic bronchitis, a form of chronic obstructive pulmonary disease (COPD), commonly affects smokers and may also be related to environmental exposures and other factors.
  • Whooping cough (whooping cough) is uncommon because of immunizations. This infection can affect unvaccinated people, or people who have been vaccinated but have a weakened immune system.

less common causes

There are many other less common conditions that can cause a cough. Some of these can be life-threatening and can worsen if not diagnosed and treated quickly.

Less common causes of persistent cough include:

  • Lung cancer: For only 2% of people with persistent cough, lung cancer is the underlying cause. About 57% of lung cancer patients cough. Cough features associated with lung cancer are difficult to distinguish from coughs from other causes.
  • Tumors in or near the lungs: Chronic cough may occur due to other tumors in the chest, such as lymphoma. Persistent cough may also occur due to lung metastases from other cancers such as breast, colon, bladder, and prostate cancer.
  • Lung diseases: including emphysema, bronchiectasis, and sarcoidosis.
  • Fungal infections: including coccidioidomycosis, histoplasmosis, and tuberculosis.
  • Sarcoidosis: Sarcoidosis is a disease in which granulomas form throughout the body, including the lungs. It usually causes a dry cough.
  • Inhalation of a foreign body: This can lead to a persistent cough and possibly infection.
  • Heart failure: Fluid buildup in the lungs caused by heart failure can lead to a persistent cough or wheezing with bloody mucus.

Should you be worried?

There are many reasons for a cough, and treatments vary widely. While nothing to worry about, ignoring a persistent cough is never a good idea.

Lung cancer has many different symptoms, and coughing may be one of them.

About half of people with lung cancer have a persistent cough at the time of diagnosis, and 2% of people with a chronic cough are found to have lung cancer.

The time between the onset of symptoms, such as a persistent cough, and the diagnosis of lung cancer can be months, and we know that lung cancer is most treatable in its early stages.

You can’t really tell if you might have lung cancer based on the characteristics of your cough. The diagnosis of lung cancer relies on biopsy and imaging studies.

It is also important to note that a chest X-ray may not identify lung cancer.

As a final note on lung cancer, keep in mind that non-smokers get lung cancer too—up to 20 percent of people who die from long-term cancer have never smoked or used tobacco.

When to see your healthcare provider

Be sure to make an appointment with your doctor if your cough persists.

If you experience chest pain, shortness of breath or dizziness, or cough up blood, you should seek immediate medical attention.

Questions you may be asked during your visit may include:

  • How long have you been coughing?
  • Has the cough worsened?
  • Is the cough steady or does it come and go?
  • Is it worse after a meal or at night?
  • Is the cough dry, or does it keep coughing up phlegm (mucus)?
  • Are you coughing up blood?
  • What other symptoms have you experienced? For example, fever, shortness of breath, allergy symptoms, wheezing, or unexplained weight loss?
  • Do you have any other medical problems?
  • Does anyone in your family have similar symptoms? Do you have a family history of bronchitis, asthma, emphysema or lung cancer?
  • Do you, or have you ever, smoked?
  • Have you been exposed to secondhand smoke?
  • What medications are you taking (including herbal supplements)?
  • Have you traveled recently?


Depending on the severity of your cough, your healthcare professional will provide you with treatment to control your symptoms and make you feel more comfortable. They may also recommend testing to determine the cause.

Blood tests can be done to look for any evidence of infection.

You may have a chest X-ray or a computed tomography (CT) scan of the chest. If you have symptoms of sinusitis, a CT scan of your sinuses may be recommended.

Other tests that may be recommended include:

  • allergy test
  • Pulmonary function tests to screen for changes in asthma and emphysema
  • An esophageal pH test to test whether acid reflux may be causing a persistent cough is an uncommon test
  • If chest imaging shows findings that look like tumors, bronchoscopy to check for foreign bodies or to evaluate your airways for tumors
  • Laryngoscopy to examine your throat and voice box


Treatment will depend on the underlying cause, and how much the cough interferes with daily activities.

VigorTip words

If you have a chronic cough, be sure to get tested. Serious causes such as cancer produce better outcomes when treatment is started early. Even if your cough isn’t caused by a serious cause, you’ll feel better and sleep better once it’s effectively treated.

Frequently Asked Questions

  • What is a persistent cough?

    A persistent cough is one that lasts eight weeks or longer. It is sometimes called a chronic, lingering or nagging cough. A persistent cough can be wet or dry and may be initially triggered by illness, allergies, or asthma.

  • What causes a persistent cough?

    Postnasal drip is a common cause of persistent cough. This can be due to allergies, colds, sinus infections, or nasal polyps. Asthma—especially cough variant asthma—or acid reflux can also be the cause of chronic cough. Smoking, ACE inhibitors, and long-term COVID can also cause persistent cough, as can chronic obstructive pulmonary disease (COPD).

    Less common causes include lung cancer, tumors in or near the lungs, emphysema, bronchiectasis, sarcoidosis, tuberculosis, and heart failure.

  • What is a prolonged COVID cough?

    A COVID cough is usually a dry cough that can last for weeks or months after contracting COVID. While the cough is usually dry, some people may develop a wet or dry cough.

    Consult your doctor if you experience a persistent COVID cough. You may need prescription medication to treat your cough.

    Things you can try to help ease your COVID cough include staying hydrated, drinking warm water or tea with honey and lemon, sucking on hard candies or cough lozenges, or taking over-the-counter cough medicines.