Cough is a reflex that helps clear the airways of secretions, protects the airway from foreign body aspiration, and can be the manifesting symptom of a disease. Cough is one of the most common complaints for which parents bring their children to a health care practitioner.
Etiology of Cough in Children
Causes of cough differ depending on whether the symptoms are acute (< 4 weeks) or chronic (> 4 weeks). (See table Some Causes of Cough in Children Some Causes of Cough in Children 
.)
The most common cause of acute cough is
The most common causes of chronic cough are
Postnasal drip
Foreign body aspiration and diseases such as cystic fibrosis Cystic Fibrosis Cystic fibrosis is an inherited disease of the exocrine glands affecting primarily the gastrointestinal and respiratory systems. It leads to chronic lung disease, exocrine pancreatic insufficiency... read more 
and primary ciliary dyskinesia are less common, but they can all result in persistent cough.
Evaluation of Cough in Children
History
History of present illness should cover duration and quality of cough (barky, staccato, paroxysmal) and onset (sudden or indolent). The physician should ask about associated symptoms. Some of these symptoms are ubiquitous (eg, runny nose, sore throat, fever); others may suggest a specific cause: headache, itchy eyes, and sore throat (postnasal drip); wheezing and cough with exertion (asthma); night sweats (tuberculosis [TB]); and, in infants, spitting up, irritability, or arching of the back after feedings (gastroesophageal reflux). For children 6 months to 6 years, the parents should be asked about potential for foreign body aspiration, including older siblings or visitors with small toys, access to small objects, and consumption of small, smooth foods (eg, peanuts, grapes).
Review of systems should note symptoms of possible causes, including abdominal pain (some bacterial pneumonias), weight loss or poor weight gain and foul-smelling stools (cystic fibrosis), and muscle soreness (possible association with viral illness or atypical pneumonia but usually not with bacterial pneumonia).
Past medical history should cover recent respiratory infections, repeated pneumonias, history of known allergies or asthma, risk factors for TB (eg, exposure to a person who has known or suspected TB infection, exposure to prisons, HIV infection, travel to or immigration from countries that have endemic infection), and exposure to respiratory irritants.
Physical examination
Vital signs, including respiratory rate, temperature, and oxygen saturation, should be noted. Signs of respiratory distress (eg, nasal flaring, intercostal retractions, cyanosis, grunting, stridor, marked anxiety) should be noted.
Head and neck examination should focus on presence and amount of nasal discharge and the condition of the nasal turbinates (pale, boggy, or inflamed). The pharynx should be checked for postnasal drip.
The cervical and supraclavicular areas should be inspected and palpated for lymphadenopathy.
Lung examination focuses on presence of stridor, wheezing, crackles, rhonchi, decreased breath sounds, and signs of consolidation (eg, egophony, E to A change, dullness to percussion).
Abdominal examination should focus on presence of abdominal pain, especially in the upper quadrants (indicating possible left or right lower lobe pneumonia).
Examination of extremities should note clubbing or cyanosis of nail beds (cystic fibrosis).
Red flags
The following findings are of particular concern:
Cyanosis or hypoxia on pulse oximetry
Stridor
Respiratory distress
Toxic appearance
Abnormal lung examination
Interpretation of findings
Clinical findings frequently indicate a specific cause ( see Table: Some Causes of Cough in Children Some Causes of Cough in Children ); the distinction between acute and chronic cough is particularly helpful, although it is important to note that many disorders that cause chronic cough begin acutely and patients may present before 4 weeks have passed.
Other characteristics of the cough are helpful but less specific. A barky cough suggests croup Croup Croup is acute inflammation of the upper and lower respiratory tracts most commonly caused by parainfluenza virus type 1 infection. It is characterized by a brassy, barking cough and inspiratory... read more 
or tracheitis Bacterial Tracheitis Bacterial tracheitis is bacterial infection of the trachea, typically causing dyspnea and stridor. Diagnosis is by direct laryngoscopy and imaging findings. Treatment is with airway control... read more 
; it can also be characteristic of psychogenic cough or a postrespiratory tract infection cough. A staccato cough is consistent with a viral or atypical pneumonia Overview of Pneumonia Pneumonia is acute inflammation of the lungs caused by infection. Initial diagnosis is usually based on chest x-ray and clinical findings. Causes, symptoms, treatment, preventive measures, and... read more . A paroxysmal cough is characteristic of pertussis Pertussis Pertussis is a highly communicable disease occurring mostly in children and adolescents and caused by the gram-negative bacterium Bordetella pertussis. Symptoms are initially those of... read more or certain viral pneumonias (adenovirus). Failure to thrive or weight loss can occur with TB Tuberculosis (TB) Tuberculosis is a chronic, progressive mycobacterial infection, often with an asymptomatic latent period following initial infection. Tuberculosis most commonly affects the lungs. Symptoms include... read more 
or cystic fibrosis Cystic Fibrosis Cystic fibrosis is an inherited disease of the exocrine glands affecting primarily the gastrointestinal and respiratory systems. It leads to chronic lung disease, exocrine pancreatic insufficiency... read more . Nighttime cough can indicate postnasal drip or asthma Wheezing and Asthma in Infants and Young Children Wheezing is a relatively high-pitched whistling noise produced by movement of air through narrowed or compressed small airways. It is common in the first few years of life and is typically caused... read more . Coughing at the beginning of sleep and in the morning with waking usually indicates sinusitis Sinusitis Sinusitis is inflammation of the paranasal sinuses due to viral, bacterial, or fungal infections or allergic reactions. Symptoms include nasal obstruction and congestion, purulent rhinorrhea... read more 
; coughing in the middle of the night is more consistent with asthma. In young children with sudden cough and no fever or URI symptoms, the examiner should have a high index of suspicion for foreign body aspiration.
Testing
Children with red flag findings should have pulse oximetry and chest x-ray. All children with chronic cough require a chest x-ray.
Children with stridor, drooling, fever, and marked anxiety need to be evaluated for epiglottitis typically in an operating room by an ear, nose, and throat specialist prepared to immediately place an endotracheal or tracheostomy tube. If foreign body aspiration is suspected, chest x-ray with inspiratory and expiratory views should be done (or in some centers a chest CT).
Children with TB risk factors or weight loss should have a chest x-ray and purified protein derivative (PPD) testing or an interferon-gamma release assay.
Children with repeated episodes of pneumonia, poor growth, or foul-smelling stools should have a chest x-ray and sweat testing for cystic fibrosis.
Acute cough in children with upper respiratory infection symptoms and no red flag findings is usually caused by a viral infection. Testing is rarely indicated unless it is necessary for infection control (eg, a COVID-19 outbreak in a school or day care center). Many other children without red flag findings have a presumptive diagnosis after the history and physical examination. Testing is not necessary in such cases; however, if empiric treatment has been instituted and has not been successful, testing may be necessary. For example, if allergic sinusitis is suspected and treated with an antihistamine that does not alleviate symptoms, a head CT may be necessary for further evaluation. Suspected gastroesophageal reflux disorder Gastroesophageal Reflux in Infants Gastroesophageal reflux is the movement of gastric contents into the esophagus. Gastroesophageal reflux disease (GERD) is reflux that causes complications such as irritability, respiratory problems... read more unsuccessfully treated with an H2 blocker and/or proton pump inhibitor may require evaluation with a pH or impedance probe study or endoscopy.
Treatment of Cough in Children
Treatment of cough is management of the underlying disorder. For example, antibiotics should be given for bacterial pneumonia; bronchodilators and anti-inflammatory drugs should be given for asthma. Children with viral infections should receive supportive care, including oxygen and/or bronchodilators as needed.
Little evidence exists to support the use of cough suppressants and mucolytic agents. Coughing is an important mechanism for clearing secretions from the airways and can assist in recovery from respiratory infections. Use of nonspecific drugs for cough suppression is discouraged in children.
Key Points
Clinical diagnosis is often adequate.
A high index of suspicion for foreign body aspiration is needed if children are 6 months to 6 years of age.
Antitussives and expectorants lack proof of effect in most cases.
Obtain a chest x-ray if patients have red flag findings or chronic cough.
