Cough helps clear materials from the airways and prevent them from going to the lungs. The materials may be particles that have been inhaled or substances from the lungs and/or airways. Most commonly, material coughed up from the lungs and airways is sputum (also called phlegm—a mixture of mucus, debris, and cells ejected from the lungs). But sometimes a cough brings up blood. A cough that brings up either is considered productive. Older children (and adults) typically cough material out, but younger children usually swallow it. Some coughs do not bring anything up. They are considered dry or nonproductive.
Cough is one of the most common reasons parents bring their children to a health care practitioner.
(See also Cough in Adults Cough in Adults Cough is a sudden, forceful expulsion of air from the lungs. It is one of the most common reasons people see a doctor. The function of a cough is to clear material from the airways and to protect... read more .)
Causes of Cough in Children
Likely causes of cough depend on whether the cough has lasted less than 4 weeks (acute) or 4 weeks or more (chronic).
Common causes
For acute cough, the most common cause is
For chronic cough, the most common causes are
Postnasal drip (drainage of fluid from the nose down the throat)
Less common causes
Acute cough may also result from a foreign body (such as a piece of food or a piece of a toy) inhaled into the lungs (aspiration) or less common respiratory infections such as pneumonia Overview of Pneumonia Pneumonia is an infection of the small air sacs of the lungs (alveoli) and the tissues around them. Pneumonia is one of the most common causes of death worldwide. Often, pneumonia is the final... read more 
, pertussis Pertussis Pertussis is a highly contagious infection caused by the gram-negative bacteria Bordetella pertussis, which results in fits of coughing that usually end in a prolonged, high-pitched,... read more (whooping cough), or tuberculosis Tuberculosis (TB) Tuberculosis is a chronic contagious infection caused by the airborne bacteria Mycobacterium tuberculosis. It usually affects the lungs. Tuberculosis is spread mainly when people breathe... read more 
.
Chronic cough may also result from aspiration of a foreign body, hereditary disorders such as cystic fibrosis Cystic Fibrosis (CF) Cystic fibrosis is a hereditary disease that causes certain glands to produce abnormally thick secretions, resulting in tissue and organ damage, especially in the lungs and the digestive tract... read more or primary ciliary dyskinesia, a birth defect of the airways or lungs, inflammatory disorders involving the airways or lungs, or may be stress-related (also known as a habit or psychogenic cough).
Evaluation of Cough in Children
Not every cough requires immediate evaluation by a doctor. Knowing which symptoms may indicate a serious cause can help parents decide whether contacting a doctor is needed.
Warning signs
The following symptoms are of particular concern:
Difficulty breathing
An ill appearance
Spasms of uncontrollable, repetitive coughing followed by a high-pitched intake of air (sounds like a whoop)
When to see a doctor
Children who have warning signs should be taken to a doctor right away, as should those whose parents think they may have inhaled a foreign body. If children have no warning signs but have a frequent harsh or barking cough, parents should call the doctor. Doctors typically want to see such children within a day or so, depending on their age, other symptoms (such as fever), and medical history (particularly a history of lung disorders, such as asthma or cystic fibrosis). Otherwise healthy children who have a cough occasionally and have typical cold symptoms (such as a runny nose) may not need to be seen by a doctor.
Children with a chronic cough and no warning signs should be seen by a doctor, but a delay of a few days to a week is generally not harmful.
What the doctor does
Doctors first ask questions about the child's symptoms and medical history. Doctors then do a physical examination. What they find during the history and physical examination often suggests a cause of the cough and the tests that may need to be done (see Table: Some Causes and Features of Cough in Children Some Causes and Features of Cough in Children 
).
Information about the cough helps a doctor determine its cause. Therefore, a doctor may ask
What time of day does the cough occur?
What factors—such as cold air, body position, talking, eating, drinking, or exercise—trigger or relieve the cough?
What does the cough sound like?
Did symptoms begin suddenly or gradually?
What are the child’s other symptoms?
Does the cough bring up sputum or blood?
A nighttime cough can be caused by asthma or postnasal drip. Coughing at the beginning of sleep and in the morning when waking usually is caused by inflammation of the sinuses (sinusitis Sinusitis Sinusitis is inflammation of the sinuses, most commonly caused by a viral or bacterial infection or by an allergy. Some of the most common symptoms of sinusitis are pain, tenderness, nasal congestion... read more ). Coughing in the middle of the night is more consistent with asthma Asthma in Children Asthma is a recurring inflammatory lung disorder in which certain stimuli (triggers) inflame the airways and cause them to temporarily narrow, resulting in difficulty breathing. Asthma triggers... read more 
. A barky cough suggests croup Croup Croup is an inflammation of the windpipe (trachea) and voice box (larynx) typically caused by a contagious viral infection that causes cough, a loud squeaking noise (stridor), and sometimes... read more or sometimes a cough that is left over from a viral upper respiratory infection. A cough that started suddenly in a child with no other symptoms suggests possible inhalation of a foreign body. Contrary to what many people think, whether sputum is yellow or green or thick or thin does not help distinguish bacterial infection from other causes.
When children are 6 months to 4 years old, parents are asked about the possibility of swallowing a foreign body (such as a small toy) or small, smooth, firm foods (such as peanuts or grapes). Doctors also ask whether the child has had any recent respiratory infections, frequent bouts of pneumonia, allergies, or asthma or has been exposed to tuberculosis or other infections, as may occur during travel to certain countries.
A physical examination is done. To check for breathing problems, doctors observe the child's chest, listen to it with a stethoscope, and tap (percuss) it. Doctors also check for cold symptoms, swollen lymph nodes, and abdominal pain.
Testing
Tests may or may not be needed depending on symptoms and the causes that doctors suspect. For children with warning signs, doctors typically measure the oxygen concentration in blood using a clip-on sensor (pulse oximetry Pulse oximetry Both arterial blood gas testing and pulse oximetry measure the amount of oxygen in the blood, which helps determine how well the lungs are functioning. Arterial blood gas tests are invasive... read more ) and take a chest x-ray Chest Imaging Chest imaging studies include X-rays Computed tomography (CT) CT angiography Magnetic resonance imaging (MRI) read more . These tests are also done if children have a chronic cough or if a cough is worsening. Doctors may also do other tests depending on what they find during the history and physical examination (see Table: Some Causes and Features of Cough in Children Some Causes and Features of Cough in Children ).
For children without warning signs, tests are rarely done if the cough has lasted 4 weeks or less and cold symptoms are present. In such cases, the cause is usually a viral infection.
Tests also may not be needed if symptoms strongly suggest a cause. In such cases, doctors may simply start treatment for the presumed cause. However, if symptoms persist despite treatment, tests are often done.
Treatment of Cough in Children
Treatment of cough focuses on treating the cause (for example, antibiotics for bacterial pneumonia or antihistamines for allergic postnasal drip).
To relieve cough symptoms, parents have often been advised to use home remedies such as having the child inhale moist air (as from a cool-mist vaporizer or in a hot shower) and drink extra fluids. Although these remedies are harmless, there is little scientific evidence that they make any difference in how children feel.
Cough suppressant drugs (such as dextromethorphan and codeine) are rarely recommended for children. Cough is an important way for the body to clear secretions from the airways. Also, these drugs may have side effects, such as confusion and sedation, and there is very little evidence that they help children feel better or recover more quickly. Expectorants, which are supposed to thin and loosen mucus (making it easier to cough up), are also usually discouraged in children.
Key Points about Cough in Children
Usually, the cause of cough can be identified based on results of the doctor's examination.
In children aged 6 months to 4 years, a foreign body in the airways must be considered.
Chest x-rays are taken if children have warning signs or a cough that has lasted more than 4 weeks.
Usually, cough suppressants and expectorants are not recommended.
