What is a cough?

Coughing is your body's way of getting rid of any foreign material or mucus in your lungs. Coughing can be a response to breathing in dust or fumes that irritate the nerve endings in the airways. It can also be a symptom of a medical problem, such as a lung infection caused by bacteria or viruses, or a long-term lung disease such as asthma or chronic obstructive pulmonary disease.

Bacteria

Microscopic, single-celled organisms with DNA but no definite nucleus. Bacteria are the cause of many human diseases.

Infection

Entry into the body of microorganisms that can reproduce and cause disease.

Mucus

A thick, viscous liquid that is secreted for lubrication and to form a protective lining over certain tissues.

Nerve

One or more fibres that transmit signals of sensation and motion between the brain or spinal cord and other parts of the body.

Viruses

A microscopic infectious agent that replicates itself only within cells of living hosts; a piece of nucleic acid (DNA or RNA) wrapped in a protein coat.

Common causes of cough

Irritants

Coughing is sometimes a natural reaction to breathing in particles and gases that can irritate the airways in the lungs. Common irritants include allergens, smoke and air pollution.

Adult man coughing.Coughing is a natural reaction to irritants. 

Colds and flu

Colds and flu are common conditions that can cause coughing. They are a result of viral infections that affect the upper respiratory tract. As well as coughing, colds and flu can cause a sore throat and a stuffy or runny nose. The flu can also cause a fever and usually has worse symptoms than a cold.

Bronchitis

Bronchitis is a type of chest infection that affects the lungs. It occurs when the airways in the lungs become inflamed by presence of viruses, bacteria, smoke or air pollution. The lung inflammation causes the production of mucus, which results in a narrowing of the lung airways and coughing.

Pneumonia

Pneumonia is a lung infection that is usually caused by bacteria or viruses. It can cause a bad cough, a fever and difficulty breathing. Pneumonia is most likely to develop after having a cold or flu. It can affect people of any age, but is more common in young children, the elderly and other people with weak immune systems

Bronchiolitis

Bronchiolitis is a type of chest infection that commonly affects infants under 12 months of age. It is typically caused by viruses. At first, the symptoms of bronchiolitis may appear similar to a common cold, including a runny nose, fever and coughing. As it progresses, bronchiolitis may cause wheezing and rapid breathing.

Pertussis

Pertussis, which is also known as whooping cough, is a very contagious disease that commonly affects children under two years of age. It can also occur in older children and adults. It causes inflammation in the lungs, which leads to a distinctive 'whooping' cough. The coughing usually comes in fits of repeated fast coughs, which can last for a minute or two. The fits of coughing can be violent and leave the person gasping for air.

Croup

Croup is a common childhood condition characterised by a barking-sounding cough and noisy breathing. It occurs when an infection with a virus causes inflammation and swelling of the voice box and windpipe, making it harder to breathe. The condition most commonly affects children under five years of age. This is because up until this age, their small, soft windpipes are more likely to be affected by swelling.

Asthma

Asthma is a common disease that affects the lungs. It occurs when the airways inside the lungs are very sensitive to certain particles that enter the lungs during normal breathing and can also be brought on by exercise. As well as coughing, the main symptoms of asthma include episodes of wheezing, feeling out of breath and tightness in the chest.

Chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a condition that affects the lungs and is commonly caused by smoking. The main symptoms of COPD include feeling out of breath after exertion or, in severe cases, even when resting, but it can also cause coughing, mucus production, wheezing and tightness in the chest.

Heartburn 

Heartburn, or gastro-oesophageal reflux disease (GORD), is a type of indigestion that occurs when the stomach contents reflux up into the oesophagus. The main symptom of heartburn is a burning sensation in the lower chest and throat after eating. It can also cause coughing, especially at night or when lying down.

Allergens

An environmental substance that, although not harmful in itself, elicits a vigorous reaction from the immune system.

Bacteria

Microscopic, single-celled organisms with DNA but no definite nucleus. Bacteria are the cause of many human diseases.

Fever

An increase in body temperature above the normal temperature range. Fever is often caused by the body's immune reaction to infection.

Immune systems

The organs and cells involved in protecting the body against infection.

Infections

Entry into the body of microorganisms that can reproduce and cause disease.

Inflammation

A body’s protective immune response to injury or infection. The accumulation of fluid, cells and proteins at the site of an infection or physical injury, resulting in swelling, heat, redness, pain and loss of function.

Mucus

A thick, viscous liquid that is secreted for lubrication and to form a protective lining over certain tissues.

Oesophagus

Also called the gullet or food pipe, it is the muscular tube connecting the throat and stomach. It is lined with a mucous membrane. After ingestion, food and drink travel down the oesophagus to be digested in the stomach.

Reflux

An abnormal, backwards flow of fluid within the body.

Upper respiratory tract

The nose, sinuses, larynx and trachea parts of the respiratory tract which function to carry air to and from the lungs.

Viral

Pertaining to an illness caused by a virus.

Viruses

A microscopic infectious agent that replicates itself only within cells of living hosts; a piece of nucleic acid (DNA or RNA) wrapped in a protein coat.

Wheezing

Breathing with a whistling or rattling sound in the chest.

Methods for diagnosis

To determine the cause of your cough, a doctor will conduct a physical examination and ask you about your symptoms. During a physical examination they may use a stethoscope to listen for unusual sounds from your lungs during deep breathing.

If your doctor suspects that your cough is caused by a lung infection, they may ask you for a sample of mucus, phlegm or blood, which can then be tested for presence of bacteria or a virus. If you have a long-term cough, they may conduct some lung function tests that may help to diagnose a long-term lung condition such as asthma or chronic obstructive pulmonary disease

A man in hospital gown undergoing a physical examination by a doctor.The cause of the cough may be determined from a series of examinations.  

Bacteria

Microscopic, single-celled organisms with DNA but no definite nucleus. Bacteria are the cause of many human diseases.

Infection

Entry into the body of microorganisms that can reproduce and cause disease.

Mucus

A thick, viscous liquid that is secreted for lubrication and to form a protective lining over certain tissues.

Virus

A microscopic infectious agent that replicates itself only within cells of living hosts; a piece of nucleic acid (DNA or RNA) wrapped in a protein coat.

Phlegm

A thick, viscous substance secreted by the lining of the throat and airways, and/or from the lungs.

Medication for coughs

Coughs are usually treated by identifying and treating the underlying cause of the cough. Many different medications are also available to reduce the severity of the cough, or break down the mucus and phlegm that is then easier to dislodge from the lungs. The most suitable cough medication will depend on whether it is a dry, tickly cough or a cough that produces mucus or phlegm, so it is important to speak to your doctor or pharmacist about which type of cough medication is best for you.

Some common types of cough medication include:

  • Demulcents, which form a protective layer over the throat to help reduce coughing;
  • Mucolytics, which thin the mucus;
  • Expectorants, which loosen mucus from the airways, and;
  • Suppressants, which reduce the urge to cough.

Many over-the-counter cough medications are generally not recommended for children under six years of age without a doctor's advice. 

Mucus

A thick, viscous liquid that is secreted for lubrication and to form a protective lining over certain tissues.

Phlegm

A thick, viscous substance secreted by the lining of the throat and airways, and/or from the lungs.

When to seek medical attention

Some of the conditions that cause coughing can have complications and result in a serious illness, particularly for elderly people, children and people with weak immune systems. If coughing leads to difficulty in breathing or there are traces of blood in the phlegm, it is best to seek medical attention as soon as possible.

Immune systems

The organs and cells involved in protecting the body against infection.

Phlegm

A thick, viscous substance secreted by the lining of the throat and airways, and/or from the lungs.