It’s the middle of cold and flu season which brings with it an increasing number of patients seeking assistance with a cough. An important physiological reflex that protects the airways from aspiration of foreign materials, a cough can be a common symptom of different upper and lower respiratory tract diseases. One of the most common symptoms for which people seek medical attention, cough can be divided into three categories based on duration: acute, sub-acute cough, and chronic cough.

The most common cause of a cough is a respiratory tract infection, such as a cold or flu [Image: Freepik].

ACUTE COUGH (LASTS <3 WEEKS)

In most patients, the cause of acute cough is viral or bacterial and tends to be the result of upper respiratory tract infections such as acute bronchitis or tracheobronchitis. Most of these infections are viral in nature and tend to be self-limiting. The cough itself lasts less than three weeks and disappears once the trigger is gone. A cough that results from a cold (most common) is usually not a serious threat to a patient’s health.

Patients with a cold typically also complain of nasal stuffiness, runny nose, throat clearing, and a sore or scratchy throat. They may also feel like they have mucus dripping down the back of the throat. An acute cough can also be caused by inhaling irritants such as pollens or strong fumes, or may be the first symptom of inadequate control of asthma. Less commonly, an acute cough can be a result of more serious conditions such as pneumonia or heart failure.

“Although it’s impossible to predict whether an acute cough will become chronic, it’s important to take note that repeated cases of acute cough can be an indicator of an underlying chronic condition like asthma,” advised Muhammed Vally and Dr Mohamed Irhuma (Wits University lecturers in Pharmacology).

Treatment

The first step in the treatment of acute cough is to determine if the cough is caused by a serious condition or an acute upper respiratory infection, lower respiratory tract infection or an exacerbation of a pre-existing condition. A cough that is accompanied by a cold usually resolves without any specific medicinal treatment.

The patient should be informed that as the illness is self-limiting and harmless, no drugs need to be given, but that medications to relieve the symptoms can be prescribed. To prevent transmission, a patient should be advised to cough into their elbow rather than the hand. Frequent hand washing at times of the year when colds are prevalent is a sensible measure.

SUB-ACUTE COUGH (LASTS 3-8 WEEKS)

Sub-acute coughs are usually the result of bronchial hyper-responsiveness following a specific infection. The cough tends to be bothersome even after the inciting infection has completely resolved. According to the ACCP Evidence-Based Clinical Practice Guidelines, patients who complain of a persistent cough that lasts for three weeks after experiencing the acute symptoms of an upper respiratory tract infection may have a postinfectious cough.

Such patients are considered to have a subacute cough as this condition typically lasts between 3-8 weeks. “The cough may be caused by an upper airway irritation from inflammation, postnasal drip, or clearing of the throat due to rhinitis, tracheobronchitis or both, with without the oropharynx,” advised Dr John Mark Madison (Professor of Pulmonary, Allergy and Critical Care Medicine at University of Massachusetts).

“The characteristics of this cough, particularly in children, tends to be their paroxysmal nature as well as the inspiratory whoop associated with them. Some of the non-infectious causes of subacute coughs include gastroesophageal reflux disease (GORD), bronchial asthma and upper airway cough syndrome,” advised Vally and Dr Irhuma.

Treatment

The first step in diagnosing subacute cough is to determine whether the cough has followed a respiratory infection. According to the American Family Physician practice guidelines, if the cough does not appear to be postinfectious, it should be managed as if it were a chronic cough. Patients suspected of being infected with Bordetella pertussis (whooping cough) should have a nasopharyngeal swab for culture and those with confirmed whooping cough should receive macrolide antibiotics and be isolated for five days beginning on the first day of treatment. If the cough is not caused by bacterial sinusitis or Bordetella pertussis, treatment with inhaled ipratropium should be initiated to lessen the cough. If the patient’s cough persists, inhaled corticosteroids should be considered.

CHRONIC COUGH (LASTS >8 WEEKS)

Despite its protective role, excessive coughing can cause heightened self-consciousness and changes in lifestyle. A cough lasting for more than 8 weeks is considered as chronic. It is most commonly caused by smoking, asthma, upper airway cough syndrome (or postnasal drip syndrome, upper respiratory tract infection or gastroesophageal reflux disease (GORD). A Chest x-ray can be used to determine if the patient’s chronic cough is a symptom of a more serious condition such as pulmonary fibrosis, pulmonary neoplasm, or pneumonia.

A chronic cough may also be a complication of drug therapy such as the use of angiotensin converting enzyme (ACE) inhibitors. “Some of the less common causes of chronic cough include a varying number of diseases such as non-asthmatic eosinophilic bronchitis, chronic bronchitis, neoplasms, and even foreign bodies,” said Vally and Dr Irhuma.

Treatment

Determining the cause of a chronic cough is crucial to effective treatment. In many cases, more than one underlying condition may be the cause of a chronic cough. If a patient is a smoker, discuss plans to quit smoking and provide information to help achieve this. For patients on ACE inhibitor medication you should explore switching them to a different medicine that doesn’t have a cough as a side effect. Mayo Clinic advised medications used to treat chronic cough may include:

  • Antihistamines, corticosteroids, and decongestants: are standard treatment for allergies and postnasal drip.
  • Inhaled asthma drugs: the most effective treatments for asthma-related cough are corticosteroids and bronchodilators, which reduce inflammation and open the airways.
  • Antibiotics: if a bacterial, fungal, or mycobacterial infection is causing the chronic cough, a doctor may prescribe medications to address the infection.
  • Acid blockers: when lifestyle changes don’t take care of acid reflux, patients may need medications that block acid production. Some people need surgery to resolve the problem.