Cough

A cough is defined as “a sudden explosive expiratory manoeuvre that tends to clear material (sputum) from the airways”. In other words, coughs have a purpose, and in order to treat them effectively the underlying cause needs to be identified and treated.  Coughing protects the respiratory system by clearing it of irritants and secretions. Most people cough once or twice an hour (while awake) to maintain airway hygiene, but coughing frequently and persistently is not the norm.

By asking questions the pharmacist can ascertain whether the cough is due to less serious conditions such as colds and flu, allergic conditions or postnasal drips, or if it is due to a more serious problem like asthma, TB or even lung cancer.

Questions that will help in determining the type and severity of a cough:

• How long has the patient been coughing?
• Did it start suddenly or has it come on gradually?
• Has there been any recent change in the cough?
• Are there any associated symptoms – sputum production, chest or throat pain, shortness of breath, hoarseness?
• What factors trigger the cough – cold air, eating or drinking, talking, time of day, exercise?
• What does the patient think is causing the cough?

In general the classification of a cough is deemed acute if present for less than three weeks, sub acute when more than three weeks but less than eight. Chronic coughing is diagnosed when there has been persistent coughing for more than eight weeks.

When patients present with a persistent cough of more than 3 weeks and have some or all of the following symptoms, a doctor should be consulted:

• discoloured (green/yellow) or blood-stained sputum or nasal discharge
• rapid breathing, wheezing, worsening cough
• associated chest pain
• high fever, patient getting worse not better
• smokers and/or patients older than 40 years

These patients could have an underlying Chronic Obstructive Pulmonary Disease (COPD) which would need a medical diagnosis and treatment.

Causes

Possible causes or triggers for coughs include the following:

• infection: leading cause
• tobacco smoke
• allergic rhinitis and sinusitis with postnasal drip
• asthma
• irritation (occupational, environmental or physical agents)
• cardiac conditions
• pulmonary conditions
• gastroesophageal reflux
• side effects of certain medications

Less serious causes such as acute coughing for less than three weeks could be due to a cold or flu virus or an exogenous seasonal irritant that causes allergic rhinitis.

A cough triggered by cold air or exercise is probably due to asthma, a long-standing history of a morning cough that persists until sputum is produced is characteristic of chronic bronchitis, and a cough that is seasonal and/or associated with rhinitis and wheezing is typical of an allergic response.

Associated symptoms often highlight the probable cause e.g. a patient with pneumonia is usually unwell with a high temperature and sputum may be purulent or blood-stained, a patient with TB usually complains of night sweats and weight loss, and a patient with tracheitis will have a sore throat and a dry barking cough.

As a major function of the cough reflex is clearing secretions from the airways, it is important to ask questions about sputum production: what the sputum looks like – quantity, colour, thickness, presence or absence of blood – and how easy it is to clear. This may provide important clues as to the underlying cause of the cough.

Management

The most important component of managing a cough is identifying and then treating the underlying cause. Once the patient’s condition has been thoroughly assessed, specific medications can be prescribed to treat the primary pathology e.g. antibiotics for a bacterial infection, and inhaled bronchodilators if there are signs of bronchospasm. If there are no signs of a bacterial infection (fever, purulent sputum) nor bronchospasm, and the cough is irritating but not severe, then a simple linctus can be given for symptom relief.

• Cough suppressants: Pharmacists are often asked for a cough suppressant – exercise caution if it is a productive cough: sputum needs to be cleared. If mucus is retained and stasis promoted then infection can easily develop. Cough suppressants do have a limited role in patients with dry (non-productive) coughs, where the cough is exhausting the patient and preventing rest and sleep. Once any serious underlying cause has been excluded, a cough suppressant may be prescribed for a few nights. Most commonly used are dextromethorphan (e.g. Benylin^® Dry Cough), pholcodeine (e.g. Pholtex^® Junior and Forte) and noscapine (e.g. Nitepax^®).

• A cough, particularly a nocturnal cough, may be the only symptom of asthma. This could be the only other indicator for asthma especially if there is a family history of atopy (asthma, hay fever, eczema). These patients may also notice that exercise or cold air triggers the cough. Refer these patients to their doctors to confirm the diagnosis and to get the correct treatment. Asthma is a chronic inflammatory condition that requires treatment both of the acute episode and long-term prophylactic (preventative) treatment. Encourage all known asthmatics to comply with their treatment regimen. Patients often “feel well” and stop their medication, not realising that the inflammatory (silent) component of their illness may still be active, despite few or mild symptoms.

• Nocturnal cough may also be an early sign of congestive heart failure. Ask about ankle oedema, shortness of breath on exertion and how many pillows are required to sleep at night. If unsure, refer.

• Following a viral infection, the cough may persist for some time due to irritable airways. These patients often respond well to a bronchodilator e.g. salbutamol (Venteze^®) or ipratropium bromide (Atrovent^®) in aerosol form.

• Mucolytics e.g. Solmucol®, Mucospect® are best reserved for selected cases with chronic tenacious sputum production. The most effective (and inexpensive) way to increase bronchial secretions and liquefy viscous bronchial fluids in patients is to keep them well hydrated with oral fluids and to keep a humidifier in the room and/or do frequent steam inhalations.

• Allergic rhinitis/postnasal drip typically presents as a cough that occurs mostly or only at night and first thing in the morning, and is less noticeable, or even absent, during the day. There may be allergy-related symptoms such as itchy eyes, sneezing and a runny nose, and a postnasal drip may cause a “frog in the throat” or leave a bad taste in the mouth. Steaming and gargling can help to relieve mild symptoms. More severe cases usually respond well to a trial  treatment with a topical anti-histamine e.g. Rhinolast^® nasal spray, or an oral antihistamine e.g. Telfast^®. Symptoms should improve rapidly if the diagnosis is correct.

• Tuberculosis (TB) is an extremely common condition in South Africa, especially in lower socio-economic groups. Typical symptoms are a cough that persists for more than 3 weeks, low-grade fever and night sweats, weight loss (more than 5kg), loss of appetite, fatigue, general malaise and blood stained sputum. These patients should be referred to the nearest municipal clinic. Here, sputum samples will be taken and tested to confirm the diagnosis, and chest x-rays ordered if necessary. In children a tuberculin PPD skin test will be conducted. TB treatment is given for 6 months and is free of charge. Patients must be encouraged to comply with, and complete, the treatment regimen, to help decrease the risk of drug-resistant strains.

This is a summary of some of the active ingredients commonly prescribed for coughs and their associated side effects:

Conclusion

Taking a comprehensive history of the cough, associated symptoms and nature of the sputum, can provide the pharmacist with many helpful clues as to the underlying cause of the cough. Giving specific medication to treat the underlying cause is the most effective way to clear the cough. Additional symptom relief may be required in some cases if symptoms are particularly troublesome.  One of the products that is safe to recommend for the whole family is Prospan®.  It is currently the most popular product prescribed by paediatricians.

The pharmacist has an important role to play in the management of coughs, as the majority of coughs will respond well to over the counter remedies. However, be aware of the symptoms that indicate a more serious problem and know when to refer patients for further investigations.

Supplied by Austell Laboratories in the interest of pharmacy education