Cough : Causes, Symptoms, Diagnosis & Treatment

Last Updated: 13/08/2022

Cough is an unconditioned reflex act that occurs in response to stimulation of specific receptors and is manifested by forced exhalation after a period of tension of the respiratory muscles. The symptom is usually caused by diseases of the respiratory system, but can develop when inhaled toxic substances, foreign bodies, congestion in the lungs. To identify the cause of the cough, x-rays, spirometry, fibrobronchoscopy, and laboratory tests are performed. For the relief of symptoms, antitussive and expectorant drugs, mucolytics are used.

general characteristics

A cough is a forced exhalation through the mouth with characteristic sounds. Often it is preceded by a feeling of soreness or scratching in the throat, tightness in the chest. In most cases, the coughing act is accompanied by pain in the chest. Cough may result in the release of yellow-green, "rusty", glassy and other types of sputum, typical of certain diseases. With a prolonged coughing attack, reflex vomiting is sometimes possible, the blueness of the nasolabial triangle due to hypoxia.

More often, coughing occurs against the background of other symptoms of damage to the respiratory system: sore throat, chest, nasal congestion. When the vocal apparatus is involved, the symptom is combined with hoarseness up to aphonia. In severe illness, coughing shocks can follow one after another without interruption, which is called a cough reprise. The presence of a persistent cough in a patient, especially with the release of purulent or bloody sputum, a violation of the general condition is a direct indication for a visit to a pulmonologist.

Development mechanism

The cough act is a complex reflex defense mechanism that is necessary to cleanse the airways of foreign bodies, toxins and excess mucus. The cough reflex begins with irritant receptors in the larynx and tracheobronchial tree, which are innervated by fibers of the vagus nerve. The most sensitive to external influences are the vocal cords, the epiglottis, the bifurcation zone of the trachea into the bronchi. The receptors respond to mucus, chemicals, pollutants, and large foreign bodies.

Excitation from irritant nerve endings is directed to the cough center located in the medulla oblongata and to the neurons of the reticular formation. These structures are responsible for the coordinated work of all muscle groups involved in the act of coughing. The first phase of the reflex includes a deep short breath lasting about 2-3 seconds, which is accompanied by a spasm of the muscles of the larynx and glottis, an increase in the tone of the muscles of the bronchi. Intrathoracic pressure can reach 14mm Hg. Art.

This is followed by a sharp contraction of the abdominal muscles, the diaphragm to overcome the increased resistance with a rapid exhalation through the mouth. The air flow velocity during coughing reaches 50-12 m/s, which is 25-3 times higher than during quiet breathing. Together with a stream of air, droplets of mucus, dust, and foreign particles are removed from the bronchopulmonary system. Forced expiration ends a single coughing act, but with excessive irritation of the receptors, the reflex can be repeated many times.

There are no sensitive nerve endings in the lung parenchyma itself, therefore, with primary lesions of the lungs, coughing indicates the progression of the disease, the involvement of the bronchi or pleura in the pathological process. The cough reflex can also be formed in cardiac pathology, which contributes to an increase in pressure in the pulmonary vascular system. This leads to the release of the liquid part of the blood into the alveoli and interstitial tissue, which ends with irritation of the receptors, an intense cough, which is aggravated in a horizontal position.



Cough is not a specific sign of any disease, but its diagnostic value increases with the identification of specific features of the appearance of a symptom. When classifying, they are guided by the presence or absence of sputum, timbre, frequency, duration, frequency of occurrence during the day. The most common and important for diagnosis is the allocation of varieties of coughing act, depending on the presence of a secret:

  • Dry cough . It is not accompanied by secretion from the respiratory tract. The appearance of a symptom is observed in the initial stage of bronchitis, pneumonia, with the localization of the inflammatory process in the larynx or trachea. An attack can occur with damage to the pleura, mediastinum, compression of the airways by volumetric formations, fibrosing processes in the lungs.
  • Wet cough . Always ends with sputum, which may have a different color, viscosity and smell. Purulent sputum is more typical for inflammatory diseases of the respiratory tract, "vitreous" - for an attack of bronchial asthma. The presence of blood streaks may indicate neoplasms in the lungs, pathology of the cardiovascular system.

There is a classification according to volume and timbre, there is a "barking" cough, characteristic of laryngitis, false croup in children, deaf weakened in chronic obstructive bronchitis, silent, indicating the destruction of the vocal cords. A bitonal cough is distinguished into a separate category, in which an additional high tone sounds, most often indicating the development of tumorous bronchoadenitis in childhood.

In diagnostic terms, it is important to classify the symptom according to the time of manifestation: morning cough is more often detected in smokers and asthmatics, nocturnal attacks are pathognomonic for tuberculosis and cardiac asthma. With inflammation of the respiratory tract, there is no connection between the symptom and the time of day. According to the mechanism of symptom formation, central (neurotic), associated with direct excitation of reflex zones in the brain in neurosis, and reflex cough, caused by irritation of the nerve endings of the respiratory system, upper esophagus, are distinguished.

Causes of cough

Causes of a superficial cough

The symptom occurs in healthy people when inhaling air polluted with pollutants, pungent odors. Coughing is usually associated with damage to the upper respiratory tract. There are the following causes of superficial cough:

  • SARS : influenza, adenovirus infection.
  • The defeat of the ENT organs : chronic tonsillitis, bacterial pharyngitis and rhinopharyngitis, postnasal drip syndrome.
  • Childhood infections : the initial period of measles and rubella, parapertussis.
  • allergic processes .
  • Foreign bodies of the respiratory tract .
  • Complications of pharmacotherapy : taking antihypertensive drugs (ACE inhibitors, beta-blockers), antiarrhythmic drugs.
  • Rare causes : neurosis of the pharynx, thyroid cancer.

Causes of a deep dry cough

Intense cough paroxysms without sputum production are most characteristic of the localization of the pathological process in the lower respiratory tract. The symptom can be combined with chest pain, shortness of breath. An attack of dry deep cough is provoked by the following reasons:

  • Inflammatory processes in the respiratory organs : laryngotracheitis, bronchitis, whooping cough.
  • Tuberculosis : pulmonary form, acute disseminated variant, damage to the lymph nodes of the mediastinum.
  • Non-inflammatory diseases of the bronchi : Williams-Campbell syndrome, bronchial foreign body, broncho-obstructive syndrome.
  • Pulmonary diseases : pneumosclerosis, acute atelectasis, malignant tumors.
  • Causes of the pleura : benign and malignant tumors, pleurisy, pneumothorax.
  • Allergic pathology : bronchial asthma, alveolitis, asthmatic bronchitis.
  • Diseases of other organs : diverticula of the esophagus, dilated cardiomyopathy, pericarditis.
  • Occupational diseases : berylliosis, silicosis, silicosis.

Causes of wet cough

Normally, after coughing, a tiny amount of clear mucus is separated from a person, but more often a wet cough is caused by damage to the respiratory system. Usually, after coughing up sputum, the patient feels relief. Common causes of cough with phlegm:

  • Bronchitis : purulent (including its complication - bronchiectasis), obstructive, atrophic.
  • Pulmonary pathology : viral and bacterial pneumonia, hemosiderosis, echinococcosis.
  • Inflammation of the larynx and trachea .
  • Pulmonary edema : with complications of acute heart failure, cardiac asthma, severe lesions of the respiratory system.
  • Tumors : bronchioloalveolar carcinoma, bronchial carcinoid, squamous cell carcinoma.

Causes of barking cough

Cough paroxysms with a characteristic loud (“barking”) sound are observed when the pathological process spreads to the mucous membrane of the larynx and the vocal cords. The development of a barking cough is most often caused by:

  • Laryngeal lesions : laryngitis, true croup in diphtheria, false croup.
  • Respiratory tract infections : whooping cough, parainfluenza, adenovirus pharyngitis.
  • Tracheal diseases : complications after intubation, dyskinesia, stenosis.
  • Allergic diseases : bronchial asthma, allergic laryngitis.
  • Rare causes : berylliosis, exudative pericarditis, bronchial tuberculosis.


The most common causes of coughing are diseases of the respiratory system, so the examination is organized by a pulmonologist. To make a diagnosis, it is necessary to use a complex of instrumental methods and laboratory tests that are aimed at identifying morphofunctional disorders and signs of pathological processes. The most diagnostic value are:

  • Examination of ENT organs . To visualize the mucous membrane of the upper respiratory system, rhinoscopy, pharyngoscopy and laryngoscopy are prescribed. During the search for the cause of the symptom, attention is paid to inflammatory changes in tissues, volumetric formations, the nature and amount of sputum on the walls of organs. A smear is taken from the throat for bacterioscopy.
  • Sputum analysis . Microscopic and bacteriological examination of the discharge helps to establish the etiology of the disease. With prolonged dry cough, it is necessary to exclude infection with Koch's stick, for which sputum is sown on special nutrient media. If necessary, the study is supplemented with express methods for detecting tuberculosis.
  • X-ray methods . X-ray is recognized as the "gold standard" for diagnosing pneumonia as the main cause of cough. X-ray studies are informative in case of bronchial involvement and damage to mediastinal structures, which are often accompanied by cough. X-ray images are performed in two projections. Computed tomography is indicated for a detailed study of the structures of the chest cavity.
  • Serological reactions . Determination of antibodies to various viral and bacterial pathogens in the blood is necessary to verify the diagnosis. Modern laboratory methods are used - ELISA, RIF, PCR. Additionally, a biochemical blood test is performed to detect signs of acute inflammation; if allergies are suspected, changes in the immunogram are indicative.
  • Other instrumental methods . To visualize the structures of the bronchial tree, bronchoscopy is prescribed, during which a biopsy of pathologically altered areas is possible for cytomorphological analysis. Contrast bronchography under local anesthesia is recommended for possible tumor neoplasms.

When respiratory causes of cough are excluded, additional diagnostic methods are used: contrast radiography of the esophagus, ECG, ultrasound of the heart. To determine the degree of respiratory disorders, the gas composition of the blood is determined. In case of violations of the function of external respiration, spirography is performed with an assessment of the main indicators - forced expiratory volume, vital capacity of the lungs. Some patients need to consult an immunologist-allergist.

Inhalations for coughing



Help before diagnosis

To reduce the frequency of coughing attacks, patients are advised to avoid strong odors, sudden changes in air temperature, and limit the consumption of spicy foods and carbonated drinks. A plentiful warm drink is recommended: teas, herbal teas, dried fruit compotes. In order to clean the respiratory tract and stimulate sputum discharge, gargling with antiseptic solutions, inhalations are used. Persistent cough that lasts more than 2-3 days, accompanied by chest pain or shortness of breath, is an indication for seeking medical help and determining its cause.

Conservative therapy

Medical tactics depend on the underlying disease, the intensity and duration of cough paroxysms. With a superficial cough, softening inhalations and rinsing are sufficient, a deep dry or wet cough requires the use of specific drug therapy. Treatment is supplemented with physiotherapeutic methods, chest massage to facilitate expectoration of sputum. Taking into account the leading cause of cough, the doctor prescribes various groups of drugs:

  • Mucolytics . Means dilute sputum, improve its discharge during coughing fits. Preparations provide sanitation of the bronchial tree and accelerate recovery. As a rule, they are combined with expectorants to mutually enhance the pharmacological effects.
  • Antibiotics . Antibacterial drugs are taken for purulent inflammatory processes in the bronchial tree and lungs. The most effective are beta-lactams, macrolides. In severe SARS, antiviral agents are needed.
  • Anti-tuberculosis drugs . For the treatment of tuberculosis, there are separate drug regimens that include at least 3 drugs. To reduce side effects, vitamins and immunomodulators are prescribed.
  • Bronchodilators . Beta-adrenergic agonists, theophylline are indicated for paroxysms of cough, which are caused by reversible or irreversible bronchial constriction. In severe obstruction, glucocorticosteroids are administered by inhalation.
  • Antiallergic . The most commonly used drugs from the group of H1-histamine receptor blockers, mast cell membrane stabilizers, leukotriene inhibitors. In severe bronchial asthma, hormonal agents are used.

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