What is a cough?
A cough is a sudden, often involuntary, forceful release of air from the lungs. The cough reflex is one of the body's best defence mechanisms. Irritation or obstruction in the airways activates this reflex, and the strong rush of air helps clear material from the breathing passages. Coughs are generally described as either dry or productive. A cough is more helpful if it is producing and expelling something, such as yellowish pus. This kind of cough is termed ‘productive’ and usually should not be suppressed by drugs. Minor irritations in the throat can start the cough reflex, even though normal mucous/spittle are the only material to be expelled. This is called a ‘dry’ cough. Mucous from the nasal passages can drain into the throat and lungs (post-nasal drip) and trigger the cough reflex. Such coughs are not helpful and may be treated with cough suppressants. In diagnosing the cause of a cough, it is important to notice details about the cough, such as the type of cough, does it bring up mucous or pus, and so on. A cough that is caused by bronchitis or similar infection commonly lasts for up to 2 weeks. However, a cough that persists longer than this should be evaluated by a doctor.
A cough may indicate a serious condition if:
- blood is accompanied with cough
- it is accompanied by chest pain
- there is difficulty breathing or shortness of breath
- there is also unintentional weight loss
- there is a cough in an infant less than 3 months old
- coughing is accompanied by other symptoms such as fever or abdominal swelling.
- the cough is producing thick, foul-smelling, rusty or greenish mucous.
What are the causes?
- Smoking (smoke destroys the cells in the lining of the breathing tubes so that mucous cannot be expelled normally, leading to a chronic cough). This also includes passive smoking
- Common cold, influenza and other viral infections (with yellow or white mucous) are the most common causes
- Drugs (such as ACE inhibitors or expectorants) cause persistent, dry, non-productive coughs
- Stress (if the cough disappears during sleep, then stress may be the cause)
- Bacterial infection such as bronchitis, pneumonia, sinusitis or tracheitis
- Viral infection such as bronchiolitis, pneumonia, upper respiratory infection
- Congestive heart failure
- Environmental pollution
- Gastroesophagul reflux
- Postnasal drip
- Lung cancer
What is the diagnosis?
To determine the cause of a cough, a physician takes the medical history and performs an exam. Information regarding the duration of the cough, what other symptoms may accompany it, and what environmental factors may influence it aid the doctor in his or her diagnosis. The appearance of the sputum will also help determine what type of infection, if any, may be involved. The doctor may even observe the sputum microscopically for the presence of bacteria and white blood cells. Chest X-rays may help indicate the presence and extent of such infections as pneumonia or tuberculosis. If these actions are not enough to determine the cause of the cough, a bronchoscopy or laryngoscopy may be done. These tests use slender tubular telescopic instruments to inspect the interior of the bronchi and larynx.
How can cough be taken care of at home?
- Increasing humidity in the air helps relieve coughing. A vapourizer and a steamy shower are two ways to increase the humidity.
- Drink extra fluids to help thin secretions and make them easier to cough up.
- When a cold and a stuffy, runny nose accompany the cough, it is often caused by mucous dripping down the back of the throat. A decongestant that opens the nasal passages will relieve this postnasal drip, and is the best treatment for that type of cough.
- Decongestants are available as over-the-counter cold medications but ask your doctor before taking them. Don't give decongestants to a child under six years of age unless prescribed by the doctor. It is important to talk to your physician before using any cough medications for children under two.
- If you have high blood pressure (hypertension), consult the doctor before taking decongestants.
- Coughs due to chronic postnasal drip are probably caused by either sinus infection or allergy. If allergy is the cause, it is typically treated by avoiding the trigger (allergen) that is causing the allergy. In addition, anti-histamines and a steroid nasal spray are sometimes used to suppress the allergic inflammation.
- Dry, tickling coughs can be relieved by sucking on cough lozenges or hard candy. (However, never give a lozenge or hard candy to a child under 3 years old because it is a choking hazard.)
What is the treatment?
Treatment of a cough generally involves addressing the condition causing it. An acute infection such as pneumonia may require antibiotics, an asthma-induced cough may be treated with the use of bronchodilators, or an antihistamine may be administered in the case of an allergy. Physicians prefer not to suppress a productive cough, since it aids the body in clearing respiratory system of infective agents and irritants. However, cough medicines may be given if the patient cannot rest because of the cough or if the cough is not productive, as is the case with most coughs associated with colds or flu. The two types of drugs used to treat coughs are antitussives (drugs that suppress a cough) and expectorants (drugs that make mucous easier to cough up by thinning it).
What is the prognosis?
Since the majority of coughs are related to the common cold or influenza, most will end in seven to 21 days. The outcome of coughs due to a more serious underlying disease depends on the pathology of that disease.
What is the prevention?
It is important to identify and treat the underlying disease and origin of the cough. Avoid smoking and coming in direct contact with people experiencing cold or flu symptoms. Wash hands frequently during episodes of upper-respiratory illnesses.