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What is a cough?

Acute cough is usually caused by a viral or bacterial infection and lasts less than four weeks2.

It usually stops when the infection clears up2. Chronic cough lasts longer than 4 weeks2.  In children the definitions may be somewhat different, where acute cough is one that lasts less than 3 weeks and a prolonged acute cough lasts for 3 to 8 weeks (subacute cough).3 The British Thoracic Society defines chronic cough in children as a cough that lasts more than 8 weeks.3

The most common cause of chronic cough is smoking-related bronchitis5. In non-smokers, it is usually related to reflux, asthma, upper airways diseases, chronic lung disease and medication5. Chronic cough associated with upper airways diseases (such as chronic allergic rhinitis or chronic rhinosinusitis) is known as upper airways cough syndrome (UACS) and is one of the leading causes of chronic cough around the world5.

The sound a cough makes is caused by a sudden release of compressed air from the opening of the vocal cords and varies in depth, tone and loudness1. These sounds can help identify the underlying cause of the cough6.

Types

The simplest distinction is between wet (productive) cough and dry (non-productive) cough6.

Wet cough

A wet cough is characterised by coughing up mucous (phlegm) or you can hear mucous while coughing1,6. It is usually the result of a lower-respiratory tract infection6.

Dry cough

If you don’t produce mucous after coughing, it’s known as a dry cough6. This is usually the result of an upper-respiratory tract infection6.

Other types of cough:

Barking cough

Also called habit cough, this is most common in children aged 8 – 13 years but can be seen in children as young as 3 years and as old as 161. The sound can range from a soft cough with throat clearing to a barking cough or even coughing spasms1. The main sign that a cough is a habit is that it happens when the child is awake and stops when he/she is asleep1.

Children’s chronic cough

Cough is a common reason for children to be taken to a healthcare provider and the second most common symptom in respiratory illness after runny nose3. Cough is an important protective mechanism in children, as it keeps the airway clear3. It can be a sign of respiratory and lung infection3. A chronic cough in children can be divided into specific cough, where the underlying condition is known, and non-specific cough, where there’s no sign of an underlying condition, even after a detailed examination3. In addition, chronic cough is divided into wet and dry cough3. It should always be investigated3. Most simple respiratory infections in children are over within 3 weeks3. The cough begins in the first 2 days and lasts on average 5 days3. Healthy children cough about 11 times a day3.

Acute cough

Drying out and irritation of the membranes in the throat trigger the cough reflex, so treatment should form a soothing, anti-inflammatory film over the mucous membrane, lubricate the throat and promote salivation and swallowing2. Substances that can be used include2:

  • Honey – although not in children under 1 year because of the risk of infantile botulism
  • Polysaccharides
  • Sweet cough syrup.

Subacute cough

This is a cough that lasts 3-8 weeks and usually follows a viral or bacterial infection3.

Whooping cough (pertussis)

This is a highly infectious bacterial infection that can infect both adults and children9. It starts with cold-like symptoms and a dry cough, which typically lasts 1 to 2 weeks9. This develops into coughing spasms that may last up to a minute, with gasping for air in between, which is what makes the characteristic whoop9. These coughing spasms may also lead to vomiting which may result in dehydration9. The cough can last up to 3 months1.

Coughing in asthma

In asthma, cough is often accompanied by wheezing and breathlessness, although in some cases, there will only be the cough with no wheezing – this is called cough-dominant asthma1.

Causes

Wet cough

Possible causes for wet cough include3:

  • Bacterial bronchitis (all ages, most often 6 months to 3 years)
  • Inhaling a foreign object (most often 0 to 2 years)
  • Smoking (active smoking or passive smoke inhalation), which leads to chronic bronchitis10.

Rare causes of a wet cough include3:

  • Persistent bacterial bronchitis (all ages)
  • Complicated pneumonia (all ages)
  • Immune deficiency with recurring pneumonia (all ages)
  • Tuberculosis (TB), but the cough may also be dry (all ages)
  • Cystic fibrosis (diagnosis mostly made before the age of two)
  • Primary ciliated dyskinesia (all ages)
  • Lung malformation with recurring pneumonia (all ages, but cough in the first four weeks of life should raise suspicion)
  • Recurrent aspiration (all ages).

Dry cough

Common causes include:

  • Asthma (2 – 3 years of age)3
  • Asthmatic bronchitis (definitely < 36 months)3
  • Allergic rhinitis (> 36 months) – more commonly known as hay fever3,7
  • Rhinosinusitis (all ages) – when the child’s nasal passages become inflamed; commonly called sinusitis3,8
  • Post-infectious cough, e.g. from whooping cough or viral infections (all ages)3
  • Gastroesophageal reflux (all ages, most often 0 to 2 years)3
  • Cough receptor hypersensitivity after viral infections (all ages)3
  • Enlarged tonsils (2 to 15 years)3
  • Habit cough (5 to 6 years and most often teenagers).1,3
  • Upper airway cough syndrome – a.k.a. postnasal drip – the most common cause of chronic cough11
  • COVID-196

Rare causes of dry cough include3:

  • Ear canal irritation (all ages)
  • Medically triggered (all ages)
  • Interstitial lung disease (all ages)
  • Heart failure (all ages).

Diagnosis

In children, a healthcare provider will start by ruling out habit cough, which can be determined simply by taking a detailed history1. Once habit cough has been ruled out, the healthcare provider will use the information from the history to guide them in considering possible underlying causes for the cough1. In the case of non-specific cough, the healthcare provider may choose to wait for 2 weeks, watch for developments, and then review again12.

In adults, the healthcare provider will first rule out potential triggers12. These include12:

  • Using ACE-inhibitor medication
  • Environmental factors
  • Smoking
  • Chronic obstructive pulmonary disease (COPD)
  • Red flags that suggest a serious underlying condition.

They will then do a clinical examination and begin treatment, focusing on common causes of cough first12. If necessary, they may refer you for X-rays12.

Treatment

Treatment principles

It is best to treat the underlying condition3. If the underlying cause of the cough can be identified, the healthcare provider will begin the necessary treatment for the cause12. If not, they can begin initial treatment with the options listed below12.

Treatment options

In adults, initial treatment options for chronic cough include:

  • Decongestant combined with first-generation antihistamine11,12
  • Intranasal corticosteroids11,12
  • Saline nasal rinse12
  • Antihistamine11,12
  • Cough medicine.11

In children, treatment options for allergic rhinitis and cough include3:

  • Oral antihistamines
  • Intranasal corticosteroids
  • Limiting exposure to allergens.

Prevention

Ways to help prevent the spread of germs that cause respiratory illnesses include13:

  • Covering your mouth and nose with a tissue when coughing or sneezing
  • Throwing away used tissues in the bin
  • Coughing and sneezing into your elbow instead of your hands
  • Washing hands frequently with soap and water for at least 20 seconds
  • Using hand sanitiser that contains at least 60 % alcohol when no soap and water are available
  • Avoiding close contact with people who are sick
  • Avoiding close contact with other people when you are sick.

Helpful tools

Different cough medicines work in different ways and include14:

  • Antitussives – reduce the urge to cough
  • Expectorants – increase mucous production, making it easier to remove.
  • Mucolytics – make mucous thinner and easier to cough up
  • Antihistamines – reduce congestion and mucous production as a result of allergy
  • Antihistamine-decongestant combinations – reduce congestion, as well as reducing mucous production resulting from allergy  
  • Honey – kills bacteria.