Cough

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Overview
A cough, also known as tussis is a sudden, often repetitive, spasmodic contraction of the thoracic cavity, resulting in violent release of air from the lungs, and usually accompanied by a distinctive sound.

Coughing is an action the body takes to get rid of substances that are irritating the air passages. A cough is usually initiated to clear a buildup of phlegm in the trachea. Coughing can also be triggered by a bolus of food entering the trachea rather than the esophagus due to a failure of the epiglottis. Frequent or chronic coughing usually indicates the presence of a disease. Provided the patient is a non-smoker and has a normal chest X-ray, the cause of chronic cough in 93% of all patients is due to asthma, heartburn or post-nasal drip. Other causes of chronic cough include chronic bronchitis and medications such as ACE inhibitors. Coughing can happen voluntarily as well as involuntarily.

Physiology
A cough is a protective, primitive reflex in healthy individuals. The cough reflex is initiated by stimulation of two different classes of afferent nerves, namely the myelinated rapidly adapting receptors, and nonmyelinated C-fibers with endings in the lungs.

Cause
A persistent cough can be debilitating, socially distressing, and adversely impair quality of life. One of the more common presentations to a medical practitioner is a dry cough. The common causes of chronic dry coughing include post-nasal drip, gastroesophageal reflux disease, asthma, post viral cough and certain drugs such as beta blockers, ACE inhibitors and aspirin. If a cough lasts for more than three weeks, multiple causes are likely and symptoms will abate only when all the causes are treated will the patient be symptom free. Individuals who smoke often have a smoker's cough, a loud, hacking cough which often results in the expiration of phlegm.

Coughing may also be used for psychological or social reasons, such as the coughing before giving a speech. This is known as psychogenic, habit or tic coughing, and may increase in frequency in social situations featuring conflict.

Given its irritant nature to mammal tissues, capsaicin is widely used to determine the cough threshold and as a tussive stimulant in clinical research of cough suppressants.

Nonproductive Cough

 * Smoker's cough
 * Aspiration
 * Congestive heart failure
 * Postnasal drip
 * Most common cause of chronic cough in nonsmokers
 * GERD
 * Second most common cause of chronic cough in nonsmokers
 * Asthma/reactive airway disease
 * ACE inhibitor use
 * Pneumonia
 * Typical pneumonia is characterized by acute or subacute onset of fever, dyspnea, fatigue, pleuritic chest pain, and cough
 * Atypical pneumoniais characterized by more gradual onset, dry cough,headache, fatigue, and minimal lung signs
 * Acute bronchitis
 * Most commonly caused by viruses
 * Postviral bronchitis may last beyond 6 weeks
 * Aspirated foreign body
 * Lung cancer
 * COPD
 * Sarcoidosis
 * Cryptogenic organizing pneumonia
 * Filarial disease

Productive Cough

 * Postnasal drip
 * Tuberculosis
 * COPD
 * Lung cancer
 * Smoker's cough
 * Asthma with secondary infection
 * Pneumonia
 * Bronchitis

Complete Differential Diagnosis of Cough Sorted by Frequency of Causes
In alphabetical order.

Most Common Causes

 * Allergic Rhinitis
 * Asthma
 * Bronchiectasis
 * Gastroesophageal Reflux Disease (GERD)
 * Post-nasal drip

Other Causes

 * Abacavir
 * Abatacept
 * Abrin
 * ABVD
 * ACE inhibitor
 * Acetylmorphone
 * Achalasia
 * Acute bronchitis
 * Acute Chest Syndrome
 * Acute viral nasopharyngitis (common cold)
 * Acyclovir
 * Adalimumab
 * Adefovir
 * Adenoid hypertrophy
 * Adenoviridae
 * Albuterol
 * Alcoholism
 * Alefacept
 * Alfuzosin
 * Aliskiren
 * Allergic bronchopulmonary aspergillosis
 * Amiodarone
 * Amlodipine and Benazepril
 * Amphotericin B
 * Anagrelide
 * Anastrozole
 * Aortic arch anomalies
 * Aphthovirus
 * Ascaris infection
 * Aspergillosis
 * Aspirated foreign bodies
 * Atazanavir
 * Atelectasis
 * Atopic rhinitis
 * Atrial myxoma
 * Atypical pneumonia
 * Benazepril
 * Bepridil
 * Beriberi Heart Disease
 * Bevacizumab
 * Bitolterol
 * Blastomycosis
 * Bordetella pertussis
 * Bortezomib
 * Brimonidine
 * Bronchial stenosis
 * Bronchial web
 * Bronchiolitis
 * Bronchitis
 * Bronchogenic cyst
 * Budesonide
 * Busulfan
 * Byssinosis
 * Cadmium poisoning
 * Caplan's Syndrome
 * Captopril
 * Carvedilol
 * Cerumenosis
 * Cervical mass
 * Cetuximab
 * Cevimeline
 * Chest tube
 * Chickenpox
 * Chlamydophila pneumoniae
 * Chlorambucil
 * Choking
 * Cholesterol pneumonia
 * Chronic beryllium disease
 * Chronic Fatigue Syndrome
 * Chronic Obstructive Pulmonary Disease
 * Ciliary dyskinesia
 * Cladosporium
 * Cladribine
 * Clobutinol
 * Clofarabine
 * Clofedanol
 * CMV Pneumonitis
 * Coccidioidomycosis
 * Community-acquired pneumonia
 * Congenital nephrotic syndrome
 * Congestive Heart Failure
 * Co-trimoxazole
 * Cromolyn Sodium
 * Croup
 * Cryptococcosis
 * Cystic fibrosis
 * Cytarabine
 * Dacarbazine
 * Dactinomycin
 * Darbepoetin Alfa
 * Diborane
 * Docetaxel
 * Domiodol
 * Dornase alfa
 * DTPA
 * Ear foreign body
 * Efalizumab
 * Efavirenz
 * Emtricitabine
 * Enalapril
 * Enfuvirtide


 * Epinastine
 * Eplerenone
 * Epoetin Alfa
 * Eprosartan
 * Erlotinib
 * Esophageal atresia
 * Esophageal cancer
 * Esophageal dysmotility
 * Estradiol Topical
 * Etanercept
 * Fasciolosis
 * Fexofenadine
 * Filariasis
 * Floxuridine
 * Fludarabine Phosphate
 * Fluorouracil
 * Fluticasone and Salmeterol
 * Fluvastatin
 * Fosamprenavir
 * Fosinopril
 * Gabapentin
 * Ganciclovir
 * Gefitinib
 * Gemcitabine Hydrochloride
 * Glyburide and Metformin
 * Gnathostomiasis
 * Goiter
 * Goodpasture's syndrome
 * Granisetron
 * Hair in the ear canal
 * Hamman-Rich syndrome
 * Hay fever
 * Histoplasmosis
 * Histrelin
 * Human ehrlichiosis
 * Human flu
 * Hypotension
 * Ibandronate
 * Idiopathic Pulmonary Fibrosis
 * Ifosfamide
 * Iloprost
 * Imipramine
 * Infectious mononucleosis
 * Influenza
 * Insulin Human (rDNA Origin)
 * Interferon beta-1a Intramuscular
 * Interstitial pneumonia
 * Isoproterenol
 * Juvenile Myelomonocytic Leukemia (JMML)
 * Kaposi's sarcoma
 * Ketorolac
 * Lady Windermere syndrome
 * Lamivudine
 * Lamotrigine
 * Laryngeal cancer
 * Laryngitis
 * Laryngopharyngeal Reflux Disease
 * Laryngotracheal cleft
 * Lassa fever
 * Legionellosis
 * Letrozole
 * Levalbuterol
 * Lisinopril
 * Lomustine
 * Low humidity
 * Lower respiratory tract infection
 * Lung abscess
 * Lymphangitis carcinomatous
 * Lymphocytic interstitial pneumonia
 * Mallory-Weiss syndrome
 * Measles
 * Mechlorethamine
 * Mediastinal tumor
 * Melioidosis
 * Melphalan
 * Mercaptopurine
 * Mesalamine
 * Mesothelioma
 * Metaproterenol
 * Methotrexate
 * Metoprolol
 * Miliary tuberculosis
 * Mitomycin
 * Mitral stenosis
 * Moexipril
 * Moxifloxacin
 * Mucor stolonifer
 * Mycophenolic acid
 * Mycoplasma pneumoniae
 * Natalizumab
 * Nateglinide
 * Nedocromil
 * Nickel carbonyl
 * Nicotine nasal spray
 * Nilutamide
 * Nitrofurantoin
 * Nocardiosis
 * Occupational exposure of irritants
 * Omeprazole
 * Oxaliplatin
 * Oxcarbazepine
 * Paclitaxel


 * Pamidronate
 * Paprika splitter's lung
 * Paracoccidioidomycosis
 * Papillomatosis
 * Paragonimus Infection
 * Passive smoking
 * Pegaspargase
 * Peginterferon alfa-2a
 * Pemetrexed
 * Penbutolol
 * Pentamidine
 * Perindopril
 * Peripartum cardiomyopathy
 * Pertussis
 * Pharyngitis
 * Pimecrolimus topical
 * Pirbuterol acetate
 * Pleurisy
 * Pleuropulmonary blastoma
 * Plicamycin
 * Pneumocystis jirovecii pneumonia
 * Polymer fume fever
 * Post cerebrovascular accident
 * Primaquine
 * Procarbazine
 * Prograf
 * Psittacosis
 * Psychogenic cough
 * Pulmonary alveolar proteinosis
 * Pulmonary Embolism
 * Pulmonary hypertension
 * Pulmonary sequestration
 * Q Fever
 * Quinapril
 * Ramelteon
 * Ramipril
 * Rapidly progressive glomerulonephritis
 * Rhinovirus
 * Ribavirin
 * Right Ventricular Outflow Tract Obstruction
 * Risedronate
 * Risperidone
 * Rosiglitazone
 * Rosuvastatin
 * Saccharopolyspora rectivirgula
 * Salicylate sensitivity
 * Salmeterol
 * Saquinavir
 * Sarcoidosis
 * Schistosomiasis
 * Sevelamer
 * Severe acute respiratory syndrome
 * Sick building syndrome
 * Silicosis
 * Sirolimus
 * Smoking
 * Sodium stibogluconate
 * Spironolactone
 * Sporotrichosis
 * Strep throat
 * Subglottic hemangioma
 * Subglottic stenosis
 * Sulindac
 * Superior Vena Cava Syndrome
 * Tacrolimus
 * Tamsulosin
 * Thermoactinomyces sacchari
 * Thermoactinomyces vulgaris
 * Thioguanine
 * Thiotepa
 * Thoracentesis
 * Thoracic Aortic Aneurysms
 * Thymoma
 * Tipranavir
 * Tobacco smoking
 * Tocainide
 * Tonsillolith
 * Topotecan Hydrochloride
 * Tracheal stenosis
 * Tracheitis
 * Tracheoesophageal fistula
 * Tracheomalacia
 * Trandolapril
 * Transfusion-associated graft versus host disease
 * Trichinosis
 * Trimetrexate Glucuronate
 * Tuberculosis
 * Tularemia
 * Typhoid fever
 * Upper respiratory tract infection
 * Valganciclovir
 * Vinorelbine Tartrate
 * Viralcough
 * Vorinostat
 * Yersinia Pestis Infection
 * Zanamivir
 * Ziprasidone

Complete Differential Diagnosis of the Causes of Cough
(By organ system)

Complications
The complications of coughing can be classified as either acute or chronic. Acute complications include cough syncope (fainting spells due to decreased blood flow to the brain when coughs are prolonged and forceful), insomnia, cough-induced vomiting, rupture of blebs causing spontaneous pneumothorax, subconjunctival hemorrhage or "red eye", coughing defecation and in women with a prolapsed uterus, cough urination. Chronic complications are common and include abdominal or pelvic hernias, fatigue fractures of lower ribs and costochondritis.

Treatment
Coughs can be treated with cough medicines. Dry coughs are treated with cough suppressants (antitussives) that suppress the body's urge to cough, while productive coughs (coughs that produce phlegm) are treated with expectorants that loosen mucus from the respiratory tract. Centrally acting cough suppressants, such as codeine and dextromethorphan reduce the urge to cough by inhibiting the response of the sensory endings by depolarization of the vagus nerve. A recent study indicates that, because of the presence of theobromine in chocolate, 50 grams of dark chocolate may be an effective treatment for a persistent cough.

Gargling with salt and warm water can also be helpful by reducing phlegm.

During injections
Coughing during an injection can lessen the pain of the needle stick caused by a sudden, temporary rise in pressure in the chest and spinal canal, inhibiting the pain-conducting structures of the spinal cord.

Additional Resource

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