Chronic cough is usually defined as a cough that lasts for three weeks or longer. It is a very common problem and is the fifth most common symptom for which outpatient care is sought.
Although chronic cough is usually not serious, it can be associated with a variety of unpleasant effects, including physical exhaustion, self-consciousness, insomnia, headache, dizziness, muscle strain, hoarseness, excessive perspiration, and leakage of urine during coughing. In addition, the patient’s mood may be disturbed because of an underlying worry that “something is wrong.”
In almost all cases, an underlying cause for chronic cough can be found and treated.
The most common causes of chronic cough are postnasal drip, asthma, and gastroesophageal reflux disease (GERD). These three causes are responsible for up to 90 percent of all cases of chronic cough. Less common causes include infections, medications, and chronic lung diseases.
Postnasal drip is the most common cause of chronic cough. Postnasal drip is a condition that develops when secretions from the nose chronically drip into the back of the throat. These secretions can cause throat inflammation and trigger a cough.
Underlying causes of postnasal drip include allergies, colds, and sinusitis. In addition, some people have chronic inflammation of the nasal passages and runny nose, which can also cause postnasal drip.
People with postnasal drip may complain of symptoms including stuffy or runny nose, sensation of liquid in the back of the throat, or frequent throat clearing. Some people may have so-called “silent” postnasal drip; they have postnasal drip but don’t realize it. The physician will sometimes suspect postnasal drip based on the appearance of the patient’s throat. The physician will always consider, and sometimes treat, postnasal drip in a patient with chronic cough when no other apparent cause is present.
Asthma is generally reported to be the second most frequent cause of chronic cough in adults and is the leading cause in children. A cough caused by asthma is often accompanied by wheezing and shortness of breath; however, some people have a condition, known as cough variant asthma, in which cough is the only symptom of asthma.
A diagnosis of asthma as the cause of the cough is also suspected when the patient has a history of multiple allergies, or has a family history of asthma. Asthma related cough may be seasonal, may follow an upper respiratory infection, or may get worse on exposure to cold, dry air, or certain fumes or fragrances.
Gastroesophageal Reflux Disease
Gastroesophageal reflux disease, or GERD, is a disease in which acid from the stomach flows back (refluxes) into the tube connecting the stomach and the throat (the esophagus). The presence of this acidic material in the esophagus and/or its subsequent presence in the throat or even the lungs, can lead to chronic irritation and coughing. (See the “gastroesophageal reflux disease” brochure).
GERD is believed to be the third most common cause of chronic cough. Many patients with cough due to GERD complain of symptoms including heartburn or a sour taste in the mouth; however, these symptoms are absent in more than 40 percent of patients with cough due to reflux.
The doctor will ask the patient for a careful, detailed description of the history of the cough and of any other symptoms that may be present. In particular, the doctor will be interested in symptoms suggesting postnasal drip, asthma, or GERD. Taken together, these three conditions account for 90 percent of cases of chronic cough. In one study, these conditions were responsible for 99.4 percent of cases of cough in patients who were nonsmokers, did not take ACE inhibitors and had normal (or near normal) and stable chest x‑rays.
In most cases, the history and the patient’s response to treatment (see below) give the doctor enough information to determine the probable cause of the cough. The doctor may wish to obtain a chest x‑ray as part of the initial evaluation.
If asthma is suspected but cannot be confirmed, the doctor may perform lung function tests. These allow the doctor to study the pattern of airflow into and out of the lungs. A test called a methacholine challenge may also be used to help diagnose asthma. In this test, lung function is measured before and after a patient inhales a medicine called methacholine. A patient with asthma will have a decrease in lung function after inhaling this medicine. The effect of this medicine is short-lived, easily reversed with additional medication and generally not noticeable to the patient. It is a safe and commonly used test.
If the doctor needs additional information to confirm a diagnosis of GERD, a test may be ordered in which the acidity of the fluid in the esophagus is measured using a small probe that the patient swallows. Prolonged periods of high acidity suggest the presence of GERD.
If lung disease, such as bronchiectasis or lung cancer, is suspected, additional tests and a referral to a lung specialist may be required.
Treatment of chronic cough should be directed at the underlying cause. Treatment of the most common causes of chronic cough is discussed here. Patients with lung disease or less common causes of cough may be treated differently.
Treatment of postnasal drip
Patients with or without symptoms of postnasal drip may be treated for this condition to see if the cough improves. Therapy may include antihistamines and decongestants, nasal steroids, or ipratropium nasal spray. If sinusitis is suspected as the cause of the postnasal drip, antibiotics may be helpful.
Treatment of cough variant asthma
Patients whose cough is due to asthma will receive standard treatment for asthma, which includes inhaled bronchodilators and inhaled steroids. These inhaled medicines act to decrease inflammation (swelling) of the airways. In some cases, oral steroids are given for a limited period of time. (See the “managing asthma” brochure).
Treatment of gastroesophageal reflux
Cough due to GERD usually responds to a regimen that includes one or more of the following:
- Avoiding intake of substances that increase reflux, such as foods with high fat content, chocolate, and excessive alcohol.
- Stop smoking
- Eating three meals a day without snacking.
- Avoiding meals for two to three hours before lying down.
- Elevating the head of the bed while sleeping.
- Taking medication to decrease acidity in the stomach.
- These measures are usually effective in someone with confirmed GERD, but the time it takes for patients to see improvement in cough can be as long as six months. (See the “gastroesophageal reflux disease” brochure).
Your doctor is the best resource for finding out important information related to your particular case. Not all patients with chronic cough are alike and it is important that your situation is evaluated by someone who knows you and your history well.