What causes a chronic cough?
A chronic cough is when a cough lasts longer than 8 weeks in adults or 4 weeks in children. Common causes include asthma, allergies, gastroesophageal reflux disease (GERD), or bronchitis. Less commonly, it can be a sign of a more severe condition, such as a heart cough or lung disease.
In this article, we take a close look at the causes and symptoms of a chronic cough, ways to treat it, and when to see a doctor.
What causes a chronic cough?
A variety of factors can cause a chronic cough. Sometimes, more than one factor may be responsible.
When an adult has a cough that persists for more than 8 weeks, it is considered a chronic cough.
Some of the more common causes of chronic cough include:
- Asthma. Asthma occurs when a person's upper airways are especially sensitive to cold air, irritants in the air, or exercise. One type of asthma, known as cough-variant asthma, specifically causes a cough.
- Bronchitis. Chronic bronchitis causes long-term inflammation of the airways that can cause a cough. This can be a part of an airway disease called chronic obstructive pulmonary disease (COPD) that typically occurs as a side effect of smoking.
- Gastroesophageal reflux disease (GERD). GERD occurs when acid comes back up from a person's stomach and into their throat. The result can be chronic irritation in the throat that leads to a cough.
- Lingering after-effects of infection. If a person has had a severe infection, such as pneumonia or the flu, they might still experience lingering effects that include a chronic cough. Even though most of their symptoms have gone away, the airways may still remain inflamed for some time.
- Postnasal drip. Also known as upper airway cough syndrome, a postnasal drip is the result of mucus dripping down the back of the throat. This irritates the throat and triggers a cough reflex.
- Blood pressure-lowering medications. Medications known as angiotensin-converting enzyme (ACE) inhibitors can cause a chronic cough in some people. These medications end in -pril and include benazepril, captopril, and ramipril.
Some less common causes of a chronic cough include:
- Aspiration. Aspiration is the medical term for when food or saliva goes down the airway instead of the food pipe. The excess fluid can collect bacteria or viruses and may lead to irritation of the airway. Sometimes aspiration can lead to pneumonia.
- Bronchiectasis. Excess mucus production can cause the airways to become larger than normal.
- Bronchiolitis. Bronchiolitis is a common condition that affects children. It is caused by a virus that causes inflammation of the bronchioles, which are small airways in the lungs.
- Cystic fibrosis. Cystic fibrosis causes excess mucus in the lungs and airways, which can cause a chronic cough.
- Heart disease. Sometimes coughing and shortness of breath can be symptoms of heart disease or heart failure. This is called a heart cough. A person with this condition may notice their cough worsens when they are lying completely flat.
- Lung cancer. While rare, persistent coughing can be a sign of lung cancer. A person with this disease may also experience chest pain as well as blood in their sputum.
- Sarcoidosis. This is an inflammatory disorder that causes small growths to develop in the lungs, lymph nodes, eyes, and skin.
A cough is typically the result of something that is irritating the airways causing the muscles in the chest and stomach to contract. The irritation also causes the glottis that covers the airways to open quickly, causing air to rush out. The result is a cough.
A cough can be 'dry' or 'wet'. A dry cough is a non-productive one, meaning the cough does not produce mucus. People who smoke cigarettes and those who take ACE inhibitors tend to have a dry cough. A wet cough is one that produces mucus or sputum. This is the case when, for example, a person has postnasal drip or cystic fibrosis.
When to see a doctor
A doctor will listen to a person's lungs to help determine the cause of a chronic cough.
A chronic cough can become a medical emergency. If a person experiences the following symptoms along with a chronic cough they should seek emergency treatment:
- a fever greater than 103°F
- coughing up blood
- chest pain
- shortness of breath or difficulty catching their breath
If a chronic cough interferes with a person's everyday activities, it often warrants further examination by a doctor. Other symptoms that may mean a person needs to see their doctor include:
- appetite loss
- coughing up a lot of mucus
- night sweats
- unexplained weight loss
To make a diagnosis, a doctor will begin by asking the person when their symptom first appeared, what makes the symptoms better, and what makes them worse. They will ask about the person's medical history and lifestyle habits, such as whether they smoke. A doctor will likely also listen to the person's lungs using a stethoscope.
Sometimes a doctor will require further testing to help with diagnosis. Tests may include:
- taking a sputum sample and evaluating it for the presence of blood or cancerous cells
- imaging scans, such as X-rays or computed tomography scans to determine if there are signs of lung disease or inflammation
- a bronchoscopy, where a doctor views the lungs for signs of irritation or disease
Each of these tests, as well as a variety of other tests, can help a doctor identify the underlying causes of a chronic cough.
Raising the head with extra pillows may help GERD-related coughs.
Treatments for a chronic cough depend upon the underlying cause. If a doctor cannot determine the exact cause straight away, they might decide to treat the most common contributing factors for a chronic cough.
Postnasal drip is a common cause, so a doctor may recommend the person takes decongestants or antihistamines. These medications can help to dry up secretions and reduce inflammation that can lead to postnasal drip. Decongestant or nasal steroid sprays may also help.
Other treatments may be more specific to a particular underlying medical condition. For example, a person may be able to control their GERD through making lifestyle changes and taking medications that reduce the effects of acid on the stomach. Examples of these changes can include:
- eating several small meals a day
- avoiding foods known to cause GERD, such as caffeine, citrus fruits, tomato-based foods, high-fat foods, chocolate, or peppermint
- refraining from lying down until two hours after eating
- sleeping with the head of the bed raised or using extra pillows to elevate the head
- taking medications, such as ranitidine (Zantac), cimetidine (Tagamet), or famotidine (Pepcid)
Those who have a cough related to ACE inhibitors may wish to talk to their doctor. There are some medications that may be able to reduce high blood pressure without causing a cough.
Unless side effects are serious, a person should not stop taking medication without first speaking to their doctor.
Smoking cigarettes can increase the risk of developing a chronic cough. Exposure to second-hand smoke can also increase a person's risk. The smoke can irritate the airways and lead to a chronic cough as well as lung damage.
Exposure to chemicals in the air, such as from working in a factory or laboratory, can also lead to long-term coughing.
Taking ACE inhibitors is a significant risk factor for coughing. According to the New England Journal of Medicine, an estimated 20 percent of people who take ACE inhibitors develop a cough.
Coughing can be problematic if it interferes with a person's daily life. A chronic cough can have the following additional effects:
- affecting a person's ability to sleep well if coughing keeps them up at night
- daytime fatigue
- difficulty concentrating at work and school
Although rare, very severe coughing can cause the following complications:
- urinary incontinence
- broken ribs
Most cases of a chronic cough can be treated, typically with over-the-counter treatments. However, sometimes a chronic cough can indicate a more serious cause that a doctor should evaluate.