Children with acute cough do not generally require any complementary examination, since progress is usually self-limiting. A chest X-ray would be indicated if there is a clinical suspicion of pneumonia or a chronic respiratory disorder, hemoptysis, sudden onset of cough or an episode of choking that might suggest aspiration of a foreign body.22 In this case, inspiration and expiration X-rays should be taken, and if there is a clear suspicion, a rigid bronchoscopy should be performed, although a flexible bronchoscopy may initially be considered. In this setting, the characteristics of the cough may sometimes assist in the diagnostic procedure: for example, cough accompanied by wheezing suggests asthma; a hacking or metallic cough may be indicative of tracheomalacia, laryngomalacia or croup; a paroxystic cough with or without stridor may suggest pertussoid syndromes; a staccato cough may be due to Chlamydia trachomatis or Mycoplasma pneumoniae infection; and a croaking, strident cough may be psychogenic.

Treatment of URTIs requires antipyretics, good hydration and aspiration of secretions. There is no placebo-controlled evidence to suggest the usefulness of antitussive syrups, antihistamines or combinations of these; indeed the adverse effects are potentially very serious, so these products should be avoided.23–26 Honey has been shown to be more effective than placebo in the treatment of cough associated with URTI.27 Bronchodilators are ineffective in non-asthmatic children, and antibiotics are recommended if bacterial infection, streptococcal tonsillitis or pneumonia is suspected.4 Educating the public and healthcare professionals about the natural history of cough associated with URTI is very important for avoiding unnecessary consultations and examinations, since in the majority of the cases, the cough will resolve two weeks after onset.28

The time and evolution, type of cough, diurnal pattern, aggravating factors and triggers, quality of the cough (dry or productive) and associated symptoms should be evaluated from the clinical records4,36,37 (Table 2). It is essential that the characteristics of the cough, whether dry or productive, are evaluated, since productive, purulent chronic cough is pathological and requires investigation for suppurative diseases. If cough is accompanied by wheezing or breathing difficulties, the spectrum of possible etiological causes is wide: asthma, foreign body, recurrent aspirations, tracheobronchomalacia, bronchiolitis obliterans, interstitial diseases, chronic pulmonary disease in pre-term infants and heart diseases, among others. When it is associated with atopic dermatitis, allergic rhinitis or sensitivity to allergens, personal and family history of allergy or asthma, occurs at night and is exacerbated with exercise, cold or exposure to irritants or allergens, a diagnosis of asthma is more probable.35 If hemoptysis is observed, pneumonia, pulmonary abscesses, BE, CF, foreign bodies, tuberculosis, pulmonary hemosiderosis, tumors, pulmonary hypertension or pulmonary arteriovenous malformations must be excluded. Nasal obstruction, mucopurulent rhinorrhea and halitosis would suggest upper airway cough syndrome or posterior nasal drip.38 Persistent headache may be a symptom of sinusitis.39 Recurrent febrile syndrome, general malaise, constitutional symptoms and a generally productive cough would indicate the need for a contact study to rule out tuberculosis.40 In aspirative syndromes, cough is generally associated with food-related regurgitation and choking.41 Psychogenic cough is dry, hacking, repetitive and frequent during the day, and calms down or disappears during sleep; it is exacerbated in the presence of parents or caregivers and diminishes with distraction and sport. It is diagnosed exclusively in a healthy child who does not improve with medication.19,20 Finally, to guide diagnosis, it is always important to determine if the patient has received any type of treatment and what effect it has had on the cough, to enquire about environmental factors (smoking in the family, daycare attendance, animals, environmental irritants, etc.) and to look for alarm signs or symptoms (neonatal onset, cough during feeding, cough with sudden onset, suppurative cough with expectoration, nocturnal sweating, associated weight loss or signs of chronic pulmonary disease, etc.). Alarm signs and symptoms in the study of children with chronic cough are listed in Table 3.

Physical examination must be complete and detailed, including the ear, nose and throat. Diagnostic tests should be requested after a full history and clinical examination have been obtained.10,15 Chest X-ray is the first study12,13,36 and, depending on the results, the following tests should be considered (Fig. 2).

• a.

  Laboratory tests: full blood panel with immunoglobulins, in case of suspected immunodeficiencies in children with cough and recurrent bacterial infections.36

• b.

  Skin tests: tuberculin sensitivity test, sweat test (electrolytes in sweat with determination of chloride) and allergy study.13

• c.

  Microbiological study: sputum or nasopharyngeal aspirate culture for study of respiratory viruses, bacterial cultures and/or cellularity studies.12–14

• d.

  Other radiological studies: chest X-ray in inspiration and expiration in case of suspected foreign body. High-resolution computed axial tomography for suspected suppurative diseases, pulmonary malformations or severe infections. Upper gastrointestinal transit (UGT) for suspected foreign bodies in the esophagus, tracheoesophageal fistulas and extrinsic compressions.12–14

• e.

  Pulmonary function: spirometry can be carried out from the age of 3–4 years with appropriate training. A positive bronchodilator test suggests asthma, but to reach a diagnosis, complementary studies (metacholine, exhaled nitric oxide or induced sputum) are required when it is normal.13,42

• f.

  Fiberoptic bronchoscopy: this should be performed in all children with chronic cough and suspicion of airway abnormalities, foreign body inhalation, aspirations, if localized radiological changes are observed or for performing bronchoalveolar lavage and microbiological studies.12,13,39

• g.

  pH monitoring: this should be performed if GERD is suspected, even though normal results do not exclude the presence of non-acid reflux, which should be evaluated with impedance testing.13,38,43

Fig. 2.

Diagnostic algorithm of chronic cough in children.

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Taken from Saranz R. Diagnóstico y tratamiento de la tos crónica en pediatría. Arch Argent Pediatr. 2013;111:140–47.

Asthma. Children with asthma can begin with cough, but most children with non-specific cough do not have asthma.44 Recurrent dry cough may be due to increased sensitivity of cough receptors,5 frequently caused by URTI. BHR is associated with wheezing but not with persistent dry cough or nocturnal cough.45 Risk factors, the characteristics of the cough, presence of wheezing and spirometry can assist in reaching a diagnosis.13,14,35,42

Persistent Bacterial Bronchitis. Until recently, persistent bacterial bronchitis was understudied and underdiagnosed. It is defined as productive chronic cough secondary to airway infection that resolves with long-term antibiotic treatment, after other diseases have been ruled out.46 The most commonly involved microorganisms are Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis, and in some cases, more than one pathogen is isolated.29,47 Definitive diagnosis is carried out by bronchoscopy and bronchoalveolar lavage, but administration of antibiotics for 2–4 weeks can be tried to see if the clinical picture resolves before carrying out a bronchoscopy. Some patients with recurrent PBB require long and repeated cycles of antibiotics, for which reason some authors propose the possibility of long-term treatment with inhaled antibiotics.48 This is a disease entity that may be associated with asthma and involves a high level of morbidity, so it should be diagnosed and treated appropriately to avoid it progressing to BE.

Upper Airway Cough Syndrome or Posterior Nasal Drip. This is one of the main causes of chronic cough in adults, but it is less common in the pediatric population.15 It is due to mechanical stimulation of the afferent branch of the cough reflex in the upper airway by secretions that descend from the nose and/or the paranasal sinuses. In preschoolers, it is caused by repeated infections due to adenotonsillar hypertrophy and/or seromucous otitis. In schoolchildren, persistent rhinitis and/or turbinate hypertrophy should suggest atopy, and if nasal polyps are observed, CF should be ruled out.2,49

Gastroesophageal Reflux Disease. The association between GERD and non-specific chronic cough in children is widely debated, since there is little evidence that this disease alone causes cough.32 For the determination of acid GERD, 24-h pH testing is sensitive and specific, while impedance is required for the diagnosis of non-acid GERD.30 UGT assists in the diagnosis of vascular rings and other causes of mechanical compression.12–14

Functional Respiratory Disorders. It is important to recognize psychogenic cough and other functional respiratory disorders in pediatric patients, since they are difficult to diagnose and are frequently labeled as asthma or upper airway cough syndrome. Psychogenic cough is less common in males, and generally occurs in schoolchildren or teenagers who, after a URTI, begin with a dry, harsh, croaking cough that occurs intermittently during the day but then disappears when the subject is distracted or sleeping. It is generally very alarming for parents, teachers and others to observe, but the patient is usually surprisingly indifferent.19,20

Chronic cough should be treated after a thorough etiological study, the aim being to eliminate the causative agent, following clinical practice guidelines.12–14 The family must be reminded to avoid exposing the child to tobacco smoke and other environmental irritants.15

Treatment of Specific Cough. Chronic cough due to asthma requires treatment with bronchodilators and, depending on classification, with inhaled corticosteroids.42 In cases of allergic rhinitis, antihistamines and nasal steroids will be required.38 Sinusitis will require treatment with antibiotics.39 GERD should be treated with proton pump inhibitors and/or surgery.50 PBB needs long-term treatment (between 2 and 6 weeks) with amoxicillin–clavulanate or clarithromycin.29,46–48 Psychogenic cough requires investigation of the causes of stress or anxiety and subsequent psychological support.12–14,19,20

Treatment of Non-specific Cough. If the cough has a moderate impact, there is no underlying disease and the child is healthy, a period of observation is recommended before diagnostic tests or treatment are initiated, with a follow-up examination of the child after 6–8 weeks. If a decision is taken to carry out a trial treatment, the duration should be empiric and based on the recommendations of experts, given the lack of controlled studies in the pediatric population.4,12,16 A trial treatment with inhaled corticosteroids at half doses is recommended for predominantly dry cough (budesonide 400μg/day or equivalent) for 2–12 weeks, depending on the guidelines. The patient should be reassessed after 2–3 weeks and if there has been no response to treatment, it should be discontinued12,13 (Fig. 3). In cases of non-specific productive cough, initiating a course of antibiotics (amoxicillin–clavulanate) for 2–3 weeks may be considered. Chang et al.51 carried out a study in children with cough of more than 4 weeks’ duration, who were randomized to follow a previously defined treatment algorithm after 4 weeks or to continue the untreated observation period for 6–8 weeks. The primary endpoint of the study was resolution of cough at 6 weeks. The duration of cough was shorter in the early treatment group. In some patients, cough resolves spontaneously, irrespective of treatment, and the diagnosis of cough as “cough variant asthma” can only be established if symptoms recur after treatment withdrawal and respond again after it is reintroduced, so a positive response with inhaled corticosteroids does not confirm the diagnosis of asthma. The use of central action antitussives, non-opiate antitussives, mucolytics or expectorants is not indicated.4 The presence of more than one cause of cough may lead to a delay in response or treatment failure if underlying conditions are not treated.

Fig. 3.

Chronic non-specific cough treatment algorithm. IC: inhaled corticosteroids.

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