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Coughing is a protective respiratory reflex, its function being to clear the airways of foreign particles or secretions that can block or irritate the airways. A cough can be a voluntary or an involuntary response to mechanical, inflammatory and chemical irritation in the tracheobronchial tree.
Gather patient information
Coughing can be a symptom of a range of infectious and non-infectious disorders with different clinical presentations, symptom duration and accompanying signs.
Coughs can be classified in three ways:
• Acute—lasting less than three weeks
• sub acute—lasting three to eight weeks
• Chronic—persisting for more than eight weeks.
They are also classified as productive or non‑productive. A productive (wet or ‘chesty’) cough expels from the lower respiratory tract secretions that could potentially impair ventilation and the lungs’ ability to resist infection. Secretions can be expelled with varying degrees of difficulty and can be clear, purulent, discolored or malodorous, although this is not considered a reliable diagnostic indicator. A non‑productive (dry or ‘hacking’) cough does not serve a functional physiological purpose.
The causes of cough can be differentiated according to the onset and duration of symptoms (as noted), although there is some overlap in the potential causes across the three classifications.
Acute cough can be caused by infection, exacerbation of a pre-existing condition, or environmental or occupational exposure to irritants. It can also be associated with a serious underlying condition.
The most common cause of acute cough is a viral upper respiratory tract infection (e.g. the common cold). Such a cough presents with a sudden onset and can be accompanied by fever and other flu-like symptoms (rhinorrhoea, sore throat). Viruses appear to cause a transient increase in cough reflex sensitivity. The cough is usually non-productive or produces a small amount of clear or white sputum. It is often worse in the evening and is generally self-limiting, lasting 7 to 10 days. Infants and young children can develop croup, a viral infection that is preceded by cold-like symptoms; this cough has a harsh, barking quality and is often associated with difficulty breathing and an inspiratory stridor.
Coughs lasting more than 14 days can indicate a secondary bacterial infection (e.g. bronchitis, sinusitis) with bacterial colonisation and purulent sputum following an acute upper respiratory viral infection. Bacterial infection can, however, also present as an acute cough with a more sudden onset. Pneumonia is characterised by a short, dry, painful cough accompanied by fever and in some cases malaise, breathlessness, chills and headaches; the cough is initially non-productive but rapidly becomes productive, with red-stained sputum.
Recent-onset cough can be a symptom of a serious underlying condition such as an acute exacerbation of chronic obstructive pulmonary disease or asthma, pneumonia, acute pulmonary embolism or foreign body aspiration.
Sub acute cough
Post-infectious cough is a common cause of sub acute cough. It tends to present as a persistent non-productive cough that can last for up to eight weeks following an acute respiratory tract infection. Among the causes can be airway inflammation, disruption of epithelial integrity, mucus hyper secretion and transient airway hyper‑responsiveness. Subacute cough usually resolves without treatment, but if it is persistent and disruptive referral for inhaled corticosteroid therapy might be required. Antibiotic therapy has no role.
The following are other causes of post-infectious cough:
• Upper airway cough syndrome (postnasal drip syndrome) can result from persistent inflammation of the sinuses. It can also be due to allergic or vasomotor rhinitis, rhinitis medicamentosa or pregnancy-associated rhinitis. It is characterized by frequent clearing of the throat, coughing when laughing or talking for prolonged periods, and exacerbation of coughing when lying down.
• Whooping cough (Bordetella pertussis) can present as a worsening cough following an initial two-week virus-like illness, with fits of coughing accompanied by post-tussive vomiting or an inspiratory whooping sound, or both.
• Gastro-oesophageal reflux disease (GORD) can be a complication of vigorous coughing; increased abdominal pressure from coughing induces or aggravates pre-existing GORD.
Chronic cough can be associated with a number of medical conditions or medications.
The age, pregnancy and breastfeeding status of the patient should be ascertained because this can affect the advice provided. Hypersensitivity or adverse reactions to other medicines or products should also be ascertained in order to guide the choice of treatment.
The predominant cause of cough in children of all ages is upper respiratory tract infection (e.g. croup). Young children generally experience 6–12 respiratory tract infections a year, most of them being viral. Other causes are more likely to be age-related:
• Infants can have structural abnormalities of the airways.
• Toddlers might be harbouring a foreign body or have asthma (nocturnal cough, wheeze, difficulty breathing, atopy, family history).
• Children can have asthma or chronic rhinitis. A productive cough is abnormal in children and
usually has an identifiable specific cause.
Medical and lifestyle history
The following medical conditions, medications or triggers can contribute to chronic cough:
• Allergic rhinitis:. This often presents as a seasonal, non-productive cough accompanied by signs and symptoms of nasal inflammation, such as nasal discharge, blockage or itching, nocturnal snoring and sneezing.
• Asthma: Poorly controlled asthma is a common cause of episodic coughing. It can be accompanied by chest tightness, expiratory wheeze, and/or exertional breathlessness and can be associated with a family history of the disorder. Symptoms can occur after exposure to trigger factors such as cold or exercise, or they can occur spontaneously at night.
• Chronic bronchitis: This is the most common cause of chronic cough. It is usually caused by tobacco smoking and is often associated with COPD.
• Chronic rhinosinusitis: This condition is characterized by chronic nasal or upper airway symptoms such as mucopurulent drainage, nasal obstruction or facial pressure.
• Environmental exposures: These include inhaled irritants such as tobacco smoke, dust, pollutants, allergens (dust mite, pollen) and chemicals (e.g. chloramines in swimming pools).
• Gastro-oesophageal reflux disease: Coughing associated with GORD can be caused by activation of the cough reflex as a result of acid-induced inflammation in the larynx or pulmonary aspiration of refluxate. Symptomatic heartburn occurs in only a minority of those affected, and the diagnosis is often made after a response to empiric treatment.
• Medications: These include ACE inhibitors (producing an irritating, tickling, or scratching sensation in the throat), beta-blockers and NSAIDs.
• Protracted bacterial bronchitis: In this instance the cough is wet, moist or productive and occurs without any identifiable specific cause and with a normal chest x-ray and spirometry. It is commonly treated with medium-term antibiotic therapy (2–6 weeks).
• Other conditions: These include tuberculosis, bronchiectasis, obstructive sleep apnoea, heart failure, carcinoma of the lung (associated symptoms can be dyspnoea, weight loss and fatigue), interstitial lung disease and psychogenic cough.
Assess patient needs
The need to refer
Referral for further investigation is necessary when a cough is accompanied by some or any of the following symptoms:
• Chest pain—possible cardiovascular cause
• Persistent fever
• Stridor and other respiratory noises—suggestive of whooping cough or croup
• Wheeze—possible asthma
• Shortness of breath—possible asthma, pulmonary embolism, congestive heart failure
• Discolored or purulent sputum –– thick, yellow or green (possible bronchiectasis or bronchitis) –– blood stained (possible lung cancer or tuberculosis) –– rust coloured (possible pneumonia) –– frothy and pink–red (possible heart failure)
• Pain on inspiration—possible pleurisy or pneumothorax.
Referral is also recommended in the following cases:
• Suspected adverse drug reaction
• Recurrent nocturnal cough, especially in children—possible asthma
•A cough that recurs regularly, especially in chronic smokers over 45 years of age
• A history or symptoms of chronic underlying disease associated with cough—e.g. asthma, COPD, chronic bronchitis
• A cough that becomes worse during self-treatment
• A cough that lasts longer than three weeks— could be indicative of a more serious underlying condition, although symptoms that are suggestive of postnasal drip or rhinitis, which can last for more than three weeks, might not necessitate referral if suitably managed.
Selection of medication for self-care of cough depends on the nature of the cough (productive or non‑productive) and its cause. Antitussives, expectorants and mucolytics are commonly found in cough medicine formulations.
Antitussives—cough suppressants such as pholcodine, dextromethorphan, dihydrocodeine and codeine— depress the cough reflex and have been used in an attempt to control disruptive cough symptoms associated with viral infections, despite the underlying cause being self-limiting. They should not be used in the case of coughs with significant mucus production and should be avoided in cases of asthma and COPD.
Although often used to reduce the frequency and intensity of coughing, antitussives do not resolve the underlying cause of the problem. Recent studies have found commonly prescribed antitussives such as codeine and dextromethorphan have limited or no efficacy relative to placebo in humans with chronic cough.
Expectorants—such as guaifenesin, ammonium salts and senega—can be useful in cases of excessive mucus production: they facilitate the removal of secretions by ciliary transport and coughing, although their clinical efficacy is unproven. Ammonium salts are contra‑indicated in cases of hepatic and renal impairment. Guaifenesin has also been shown to have antitussive properties: it reduces subjective measures of acute cough and inhibits cough-reflex sensitivity in patients with an upper respiratory tract infection, in whom cough receptors are transiently hypersensitive.
Note that the use of cough mixtures that combine an antitussive and an expectorant is not recommended.
Mucolytics—such as bromhexine—reduce mucus viscosity and facilitate the expulsion of thick, intractable secretions. Their use can reduce the frequency and duration of exacerbations in some patients with chronic bronchitis or COPD. They might, however, disrupt the gastric mucosal barrier and should be used with caution in patients with a history of peptic ulcer disease.
A number of other ingredients are also used in cough medicines:
• Antihistamines: Sedating antihistamines have been used for their anticholinergic effect and can be tried if the cough is associated with postnasal drip or allergic rhinitis. They should be avoided in the case of a productive cough because of the risk of forming viscid mucus plugs.
• Decongestants: These can be useful if a patient has nasal congestion but should otherwise be avoided. They are contra-indicated in cases of hypertension, hyperthyroidism, coronary heart disease and diabetes and with concurrent monoamine oxidase inhibitors.
• Demulcents: Honey and other demulcents have been used as traditional remedies to soothe the throat and reduce irritation contributing to a cough. They can be a safe alternative for children.
Treating cough in children
A 2008 Cochrane review reported that cough medicines for children aged <12 years were no better than placebo, and there was limited evidence to support the use of
over-the-counter cough medicines in children with acute cough. Cough and cold preparations containing varying combinations of antihistamine, antitussive, expectorant and decongestant ingredients are no longer recommended for use in children aged <6 years because of a lack of evidence for effectiveness and reports of serious adverse effects.
The function of the cough reflex is to clear secretions from the respiratory tract, and retention of these secretions can result in potentially harmful airway obstruction. In rare instances a cough can cause insomnia or repeated vomiting in a child, and in these circumstances the use of a cough suppressant might be helpful. Medication should, however, only be supplied once it has been established that there is no underlying condition requiring referral or specific therapy.
Provide counselling supported
How to use the medicine
Once a medicine has been chosen the patient should be told how to use it, the correct dose and any specific precautions:
• Dextromethorphan: Adult dose is 10–20 mg every four hours or 30 mg every six to eight hours. Maximum 120 mg daily.
• Dihydrocodeine: Adult dose is 10–20 mg three to four times a day.
• Pholcodine: Adult dose is 10–15 mg three to four times a day.
• Codeine: Adult dose is 15–30 mg three to four times a day.
• Bromhexine: Adult dose is 8–16 mg three times a day.
Most reports of serious adverse effects of these products in children have been associated with use not in accordance with the directions—i.e. misuse, medication error, accidental overdose and concurrent use of multiple products.
Always read and follow the instructions on the medicine label. Do not exceed the recommended dose, the frequency of dosing or the duration of use. Always use a medicine-measuring spoon or a medicine measure supplied with the product or obtained from a pharmacy. Kitchen spoons do not measure medicines accurately and can cause unintended overdose.
A number of cough medicine ingredients can have adverse effects:
• Dextromethorphan: Generally non-sedating with few side effects at recommended doses. Can cause hallucinations in large doses. Risk of serotonin toxicity when used with other serotonergic drugs: avoid or use combination with caution. Should not be taken within 14 days of a monoamine oxidase inhibitor.
• Codeine and dihydrocodeine: Can cause constipation and drowsiness and enhance the
effects of central nervous system depressants. Risk of dependence with prolonged use.
• Pholcodine: Less likely than codeine or dihydrocodeine to cause constipation and respiratory depression. Less likely to produce dependence.
• Guaifenesin: Generally well tolerated. Nausea and vomiting are the most common adverse effects.
• Ammonium salts: Large doses can cause nausea and vomiting.
• Antihistamines (sedating): Can result in formation of viscid mucus plugs if used for treatment of productive cough.
• Bromhexine: Adverse effects include nausea, vomiting, diarrhoea and allergic reactions.
• Decongestants: Can cause cardiovascular and central nervous system stimulation.
Additionally, some cough syrups contain a high level of sorbitol, which can cause osmotic diarrhoea if large or frequent doses are given.
Simple non-pharmacological strategies such as the use of steam, non-medicated lozenges and demulcents, adequate hydration, reducing voice use and avoiding throat clearing can be effective in reducing cough, especially when there is an irritative component.
Steam inhalations can promote expectoration. There is no evidence that adding substances such as menthol or eucalyptus to inhaled steam offers any further benefit. When used, they should be at a dilution of 5 mL in about 500 mL of hot (not boiling) water. Alternatively, steam can be inhaled during a hot shower.
Demulcents—such as glycerol, simple linctus, lemon and honey—are muco-protective agents that form a film over mucus membranes and can relieve the irritation that causes coughing by coating the throat. Oral intake of fluids is accepted as a safe and beneficial method of encouraging expectoration.e cough. Cough and cold preparations containing varying combinations of antihistamine, antitussive, expectorant and decongestant ingred