Cough That Lasts May Be Sign of Underlying Problem
April 6, 2012
Dear Mayo Clinic:
What could cause a cough that lasts for months? I take antihistamine tablets and use nasal saline spray but still cough throughout the day and at night.
Coughing is a normal reaction to irritants in your respiratory system. Coughing forcefully expels foreign bodies, mucus and other irritants, such as pollution, from your throat and clears them from your airway.
However, when a cough lasts too long, it may be a sign of an underlying problem or disease. Moreover, coughing itself becomes a problem. The forces exerted on your body by persistent coughing can result in direct physical problems — such as damage to your vocal cords, rupture of small blood vessels in your airway, fainting spells, hernias or even broken ribs. It can also harm the quality of your life, sleep and social life.
When a cough lasts longer than six to eight weeks, it's considered a chronic cough. Diagnosing the cause can be time-consuming, but is usually a critical first step which involves systematically eliminating probable causes through history taking, testing and trying different treatments. Common causes of chronic cough include:
- Postnasal drip — This is a sensation of mucus trickling from the back of your nose down into your throat. It may be due to hay fever, allergies or irritants. How postnasal drip causes a cough is still not clearly understood. In some cases, this sensation may not even be noticed. In chronic cough, postnasal drip may be due to inflammation of your nasal passages including your sinuses.
- Asthma — While unusual, asthma can present with only a cough. This is known as cough variant asthma. It doesn't necessarily mean that you will develop chronic asthma with wheezing.
- Gastroesophageal reflux disease (GERD) — With GERD, stomachacid, digestive enzymes andbile back up (reflux) into youresophagus. It may reach up to thevoice box. In severe cases, refluxmaterial may get into the lungs.These substances are irritating to your respiratory tract and can trigger a cough.
Coughing itself may cause acid reflux, turning it into a vicious cycle. While heartburn is common in reflux, not everyone with reflux experiences it. Hoarseness, throat clearing, the sensation of a tickle in the throat and cough — usually when in an upright position — may be associated with GERD affecting the throat. This is called laryngopharyngeal reflux (LPR).
- Pertussis — Chronic cough may be due to an unrecognized case of whooping cough (pertussis).
- Angiotensin-converting enzyme (ACE) inhibitors — Takento lower blood pressure, drugs inthis class include enalapril (Vasotec),lisinopril (Zestril) and others.Chronic cough can occur long after these drugs have been started. And, it may take two to three weeks for a cough to improve after stopping these medications.
- Lung disorders — Chronic cough can be caused by airway damage called bronchiectasis, and by a condition that causes asthma-like symptoms, but with normal lung function (eosinophilic bronchitis).
In smokers, persistent cough and phlegm production (chronic bronchitis) is common. Throat or lung cancer may be suspected in a smoker or former smoker who has a chronic cough that changes abruptly or lasts for more than one month following smoking cessation, or if they cough up blood or note a change in their voice.
Usually, chronic cough can be stopped by treating an underlying cause. In about 90 percent of cases, the underlying cause is postnasal drip, asthma or GERD. If sinus disease or reflux is suspected, response to treatment may help determine the cause. Sometimes, there can be more than one cause that needs to be addressed.
Depending on your diagnosis, treatment may include:
- Antihistamine allergy medications and decongestants — Theseare standard treatments for postnasaldrip. If you can identify a triggerthat causes symptoms, avoiding that triggermay be helpful. Nasal corticosteroidsprays also may be of value.
- Inhaled asthma medications — These reduce inflammation and spasms and open your airways.
- Drugs to suppress stomach acid — These help manage acidreflux. Additional measures for reducingacid reflux include losingweight if you're overweight, eatingmeals three to four hours before lyingdown for bed or elevating thehead of your bed a few inches.
- Antibiotics — If your coughing is suspected of being caused by a bacterial infection, such as a persistent sinus infection or a lung infection, antibiotics may help.
- Not smoking and avoiding secondhand smoke — In additionto causing chronic bronchitis,smoking irritates your lungs and canworsen coughs from other causes.
If no cause for your cough is found, or if the cause can't be effectively treated, drugs may be prescribed to suppress the cough, loosen mucus or relax airways.
— Kaiser Lim, M.D., Pulmonary and Critical Care Medicine, Mayo Clinic, Rochester, Minn.