Incidence	Cause
Most Likely	Viral infection
Likely	Upper airways cough syndrome (formerly known as postnasal drip and includes allergies), acute bronchitis
Unlikely	Croup, chronic bronchitis, asthma, pneumonia, ACE inhibitor induced
Very unlikely	Heart failure, bronchiectasis, tuberculosis, cancer, pneumothorax, lung abscess, nocardiasis, GORD

As viral infection is the most likely cause of cough encountered by pharmacists it is logical to ask questions that help to confirm or refute this assumption. However, it is important to differentiate other causes of cough from viral causes and also refer those cases of cough that might have more serious pathology. Asking symptom-specific questions will help the pharmacist to determine if referral is needed (Table 1.2).

Table 1.2

Specific questions to ask the patient: Cough

Question	Relevance
Sputum colour	Mucoid (clear and white) is normally of little consequence and suggests that no infection is present Yellow, green or brown sputum normally indicates infection. Mucopurulent sputum is generally caused by a viral infection and does not require automatic referral Haemoptysis can either be rust coloured (pneumonia), pink tinged (left ventricular failure) or dark red (carcinoma). Occasionally, patients can produce sputum with bright red blood as one-off events. This is due to the force of coughing causing a blood vessel to rupture. This is non-serious and does not require automatic referral
Nature of sputum	Thin and frothy suggests left ventricular failure Thick, mucoid to yellow can suggest asthma Offensive foul-smelling sputum suggests either bronchiectasis or lung abscess
Onset of cough	A cough that is worse in the morning may suggest upper airways cough syndrome, bronchiectasis or chronic bronchitis
Duration of cough	URTI cough can linger for more than 3 weeks and is termed ‘postviral cough’. However, coughs lasting longer than 3 weeks should be viewed with caution as the longer the cough is present the more likely serious pathology is responsible; for example, the most likely diagnoses of cough are as follows: at 3 days duration will be a URTI; at 3 weeks duration will be acute or chronic bronchitis; and at 3 months duration conditions such as chronic bronchitis, tuberculosis and carcinoma become more likely
Periodicity	Adult patients with recurrent cough might have chronic bronchitis, especially if they smoke Care should be exercised in children who present with recurrent cough and have a family history of eczema, asthma or hay fever. This might suggest asthma and referral would be required for further investigation
Age of the patient	Children will most likely be suffering from a URTI but asthma and croup should be considered With increasing age conditions such as bronchitis, pneumonia and carcinoma become more prevalent
Smoking history	Patients who smoke are more prone to chronic and recurrent cough. Over time this might develop in to chronic bronchitis and COPD

Clinical features of acute viral cough

Viral coughs typically present with sudden onset and associated fever. Sputum production is minimal and symptoms are often worse in the evening. Associated cold symptoms are also often present; these usually last between 7 and 10 days. Duration of longer than 14 days might suggest ‘post viral cough’ or possibly indicate a bacterial secondary infection but this is clinically difficult to establish without sputum samples being analysed.

Conditions to eliminate

Likely causes

Upper airways cough syndrome (previously referred to as postnasal drip): Postnasal drip has recently (2006) been broadened to include a number of rhinosinus conditions related to cough. The umbrella term of upper airways cough syndrome (UACS) is being adopted.

UACS is characterised by a sinus or nasal discharge that flows behind the nose and into the throat. Patients should be asked if they are swallowing mucus or notice that they are clearing their throat more than usual, as these features are commonly seen in patients with UACS. Allergies are one cause of UACS. Coughs caused by allergies are often non-productive and worse at night. However, there are usually other associated symptoms, such as sneezing, nasal discharge/blockage, conjunctivitis and itching oral cavity. Cough of allergic origin might show seasonal variation, for example hay fever. Other causes include vasomotor rhinitis (caused by odours and changes in temperature/humidity) and post-infectious UACS after an URTI. If UACS is present, it is better to direct treatment at the cause of UACS (e.g. antihistamines or decongestants) rather than just treat the cough.

Acute bronchitis: Most cases are seen in autumn or winter and symptoms are similar to viral URTI but patients also tend to exhibit dyspnoea and wheeze. The cough usually lasts for 7–10 days but can persist for three weeks. The cause is normally viral, but sometimes bacterial. Symptoms will resolve without antibiotic treatment, regardless of the cause.

Unlikely causes

Laryngotracheobronchitis (croup): Symptoms are triggered by a recent viral infection, with parainfluenza virus accounting for 75% of cases, although other viral pathogens implicated include the rhinovirus and respiratory syncytial virus. It affects infants aged between 3 months and 6 years old and affects 2 to 6% of children. The incidence is highest between 1 and 2 years of age and occurs in boys more than girls; it is more common in autumn and winter months. It often follows on from an URTI and occurs in the late evening and night. The cough can be severe and violent and described as having a barking (seal-like) quality. In between coughing episodes the child may be breathless and struggle to breathe properly. Typically, symptoms improve during the day and often recur again the following night, with the majority of children seeing symptoms resolve in 48 hours. Warm moist air as a treatment for croup has been used since the 19th century. This is either done by moving the child to a bathroom and running a hot bath or shower or by boiling a kettle in the room. However, UK guidelines (Prodigy, 2011) do not advocate humidification as there is no evidence to support its use.

Croup management is based on an assessment of severity. Advice by pharmacists should be that if symptoms persist beyond 48 hours or the child exhibits any symptoms of stridor then medical intervention is required. Standard treatment for those children with stridor would be oral or intra-muscular dexamethasone or nebulised budesonide.

Chronic bronchitis: Chronic bronchitis (CB), along with emphysema, is characterised by the destruction of lung tissue and collectively known as chronic obstructive pulmonary disease (COPD) The prevalence of COPD in the UK is uncertain. However, figures from the Health and Safety Executive (2010) estimate that over a million individuals currently have a diagnosis of COPD, and accounts for 25 000 deaths each year.

Patients with CB often present with a long-standing history of recurrent acute bronchitis in which episodes become increasingly severe and persist for increasing duration until the cough becomes continual. CB has been defined as coughing up sputum on most days for three or more consecutive months over the previous 2 years. CB is caused by chronic irritation of the airways by inhaled substances, especially tobacco smoke. A history of smoking is the single most important factor in the aetiology of CB. In non-smokers the likely cause of CB is UACS, asthma or gastro-oesophageal reflux. One study has shown that 99% of non-smokers with CB and a normal chest X-ray suffered from one of these three conditions.

CB starts with a non-productive cough that later becomes a mucopurulent productive cough. The patient should be questioned about smoking habit. If the patient is a smoker the cough will usually be worse in the morning. Secondary infections contribute to acute exacerbations seen in CB. It typically occurs in patients over the age of 40 and is more common in men. Pharmacists have an important role to play in identifying smokers with CB as this provides an excellent opportunity for health promotion advice and assessing the patient’s willingness to stop smoking.

Asthma: The exact prevalence of asthma is unknown due to differing terminologies and definitions plus difficulties in correct diagnosis, especially in children, and co-morbidity with COPD in the elderly. Best estimate of asthma prevalence in adults is approximately 4%, but it may be up to 10%. In children the figures are higher (10–15%) because a proportion of children will ‘grow out’ of it and be symptom free by adulthood.

Asthma is a chronic inflammatory condition of the airways characterised by coughing, wheeze, chest tightness and shortness of breath. Classically these symptoms tend to be variable, intermittent, worse at night and provoked by triggers. In addition, possible associated features are family or personal history of atopy and worsening symptoms after taking non-steroidal anti-inflammatory drugs (NSAIDs) or beta-blockers.

In the context of presentations to a community pharmacist, asthma can present as a non-productive cough, especially in young children where the cough is often worst at night. In these cases pay particular attention to other possible symptoms such as chest tightness, wheeze and difficulty in breathing, which may be frequent and recurrent and occur even when the child does not have a cold.

Pneumonia (community acquired): Bacterial infection is usually responsible for pneumonia and most commonly caused by Streptococcus pneumoniae (80% of cases), although other pathogens are also responsible, e.g. Chlamydia and Mycoplasma. Initially, the cough is non-productive and painful (first 24 to 48 hours), but rapidly becomes productive, with sputum being stained red. The intensity of the redness varies depending on the causative organism. The cough tends to be worst at night. The patient will be unwell, with a high fever, malaise, headache, breathlessness, and experience pleuritic pain (inflammation of pleural membranes, manifested as pain to the sides) that worsens on inspiration. Urgent referral to the doctor is required as antibiotics should be started as soon as possible.

Medicine-induced cough or wheeze: A number of medicines may cause bronchoconstriction, which presents as cough or wheeze. Angiotensin-converting enzyme (ACE) inhibitors are most commonly associated with cough. Incidence might be as high as 16%; it is not dose related and time to onset is variable, ranging from a few hours to more than 1 year after the start of treatment. Cough invariably ceases after withdrawal of the ACE inhibitor but takes 3 to 4 weeks to resolve. Other medicines that are associated with cough or wheeze are NSAIDs and beta-blockers. If an adverse drug reaction (ADR) is suspected then the pharmacist should discuss alternative medication with the prescriber, for example the incidence of cough with angiotension II receptor blockers is half that of ACE Inhibitors.

Very unlikely causes

Cough is a symptom of many other conditions, although the majority will be rarely encountered in community pharmacy. However, it is important to be aware of these rare causes of cough to ensure that appropriate referrals are made.

Heart failure: Heart failure is a condition of the elderly. The prevalence of heart failure rises with increasing age; 3 to 5% of people aged over 65 are affected and this increases to approximately 10% of patients aged 80 and over. Heart failure is characterised by insidious progression and diagnosing early mild heart failure is extremely difficult because symptoms are not pronounced. Often, the first symptoms patients experience are shortness of breath, orthopnoea and dyspnoea at night. As the condition progresses from mild/moderate to severe heart failure patients might complain of a productive, frothy cough, which may have pink-tinged sputum.

Bronchiectasis: Bronchiectasis is caused by irreversible dilation of the bronchi. Characteristically, the patient has a chronic cough of very long duration, which produces copious amounts of mucopurulent sputum (green-yellow in colour) that is usually foul smelling. The cough tends to be worse in the morning and evening. In long-standing cases the sputum is said to display characteristic layering with the top being frothy, the middle clear and the bottom dense with purulent particles.

Tuberculosis: Tuberculosis (TB) is a bacterial infection caused by Mycobacterium tuberculosis and is transmitted primarily by inhalation. After many decades of decline, the number of new TB cases occurring in industrialised countries is now starting to increase. In 2009, UK figures showed that over 9000 cases were notified – an increase of 4% on the previous year and the highest number for nearly 30 years. The incidence is higher in inner city areas (especially London and the West Midlands), among the elderly and immigrants from developing countries. TB is characterised by its slow onset and initial mild symptoms. The cough is chronic in nature and sputum production can vary from mild to severe with associated haemoptysis. Other symptoms of the condition are malaise, fever, night sweats and weight loss. However, not all patients will experience all symptoms. A patient with a productive cough for more than 3 weeks and exhibiting one or more of the associated symptoms should be referred for further investigation, especially if they fall into one of the groups listed above. Chest X-rays and sputum smear tests can be performed to confirm the diagnosis.

Carcinoma of the lung: A number of studies have shown that between 20 and 90% of patients will develop a cough at some point during the progression of carcinoma of the lung. The possibility of carcinoma increases in long-term cigarette smokers who have had a cough for a number of months or who develop a marked change in the character of their cough. The cough produces small amounts of sputum that might be blood streaked. Other symptoms that can be associated with the cough are dyspnoea, weight loss and fatigue.

Lung abscess: A typical presentation is of a non-productive cough with pleuritic pain and dyspnoea. It is more common in the elderly. Signs of infection such as malaise and fever can also be present. Later the cough produces large amounts of purulent and often foul-smelling sputum.

Spontaneous pneumothorax (collapsed lung): Rupture of the bullae (the small air or fluid filled sacs in the lung) can cause spontaneous pneumothorax but normally there is no underlying cause. It affects approximately 1 in 10 000 people, usually tall, thin men between 20 and 40 years old. Cigarette smoking and a family history of pneumothorax are contributing risk factors. This can be a life-threatening disorder causing a non-productive cough and severe respiratory distress. The patient experiences sudden sharp unilateral chest pain that worsens on inspiration. The symptoms often begin suddenly, and can occur during rest or sleep.

Gastro-oesophageal reflux disease: Gastro-oesophageal reflux disease (GORD) does not usually present with cough but patients with this condition might cough when recumbent (lying down). The patient might show symptoms of reflux or heartburn. Patients with GORD have increased cough reflex sensitivity and respond well to proton pump inhibitors. It should always be considered in all cases of unexplained cough.

Nocardiasis: Nocardiasis is an extremely rare bacterial infection caused by Nocardia asteroides; it is transmitted primarily by inhalation. It is very unlikely a pharmacist will ever encounter this condition and is included in this text for the sake of completeness. It has a higher incidence in the elderly population, especially men. The sputum is purulent, thick and possibly blood tinged. Fever is prominent and night sweats, pleurisy, weight loss and fatigue might also be present.

Figure 1.1 will aid the differentiation between serious and non-serious conditions of cough in adults.

Trigger points indicative of referral

Cough

Symptoms/signs	Possible danger/reason for referral
Chest pain Haemoptysis Pain on inspiration Wheeze and/or shortness of breath	All are symptoms outside remit of community pharmacist
Duration longer than 3 weeks Cough that recurs on a regular basis	Suggests non-acute cause of cough and requires further investigation
Debilitating symptoms in the elderly	This patient group at greater risk of complications
Persistent nocturnal cough in children	Suggests possible asthma

Fig. 1.1 Primer for differential diagnosis of cough in adults
Duration of cough
Coughs lasting longer than 3 weeks are considered chronic in nature. Most acute, self-limiting coughs usually resolve within 3 weeks; conditions with sinister pathology are more likely the longer the cough has been present. However, not all coughs that have lasted 3 weeks have to be referred automatically. Postnasal drip and seasonal allergies (e.g. hay fever) can persist for weeks and be managed by community pharmacists.
Referral symptoms
Certain symptoms warrant direct referral to the GP or even casualty. For example, shortness of breath, breathlessness (possible asthma), chest pain (possible cardiovascular cause) or pain on inspiration (pleurisy or pneumothorax).
Sputum colour
Sputum colour can be helpful in deciding when to refer. However, there is a common misconception that patients who present with green-yellow or brown sputum have a bacterial infection; this is not normally the case. If the cough has persisted for more than 7 to 10 days it is possible that an initial viral infection has become secondarily infected with a bacterial infection. This could indicate referral, especially if the symptoms are debilitating or if the patient is elderly.
Symptoms associated with infection
The patient might have associated symptoms of fever, rhinorrhoea and sore throat.
Haemoptysis
Blood in the sputum requires further investigation, especially if the person has had the symptoms for a period of time.
Trigger factors
Certain atmospheric factors can trigger cough. These factors include air temperature changes, pollution (e.g. cigarette smoke) and dry atmospheres (e.g. air conditioning).

Evidence base for over-the-counter medication

Cough is often trivialised by practitioners but coughing can impair quality of life and cause anxiety to parents of children with cough. Patients who exercise self-care will be confronted with a plethora of over-the-counter (OTC) medication and many will find the choice overwhelming. The pharmacist must ensure that the most appropriate medication is selected for the patient, but this must be done on an evidence based approach.

All the active ingredients to treat cough were brought to the market many years ago when clinical trials suffered from flaws in study design compared to today’s standards, thus clinical efficacy is therefore difficult to establish.

Expectorants

A number of active ingredients have been formulated to help expectoration, including guaifenesin, ammonium salts, ipecacuanha, creosote and squill. The majority of products marketed in the UK for productive cough contain guaifenesin, although products containing squill (e.g. Buttercup Syrup) are available. The clinical evidence available for any active ingredient is limited. Older ingredients such as ammonium salts, ipecacuanha and squill were traditionally used to induce vomiting as it was believed that at subemetic doses they would cause gastric irritation, triggering reflex expectoration. This has never been proven and belongs in the annals of folklore. Guaifenesin is thought to stimulate secretion of respiratory tract fluid, increasing sputum volume and decreasing viscosity so assisting in removal of sputum. Guaifenesin is the only active ingredient that has any evidence of effectiveness. Two studies identified by Smith, Schroeder & Fahey (Cochrane Review 2008) found conflicting results for guaifenesin as an expectorant. In the largest study (n = 239) participants stated guaifenesin significantly reduced cough frequency and intensity compared to placebo. In the smaller trial (n = 65) guaifenesin was stated to have an antitussive not expectorant effect.

Summary

Based on studies, guaifenesin is the only expectorant with any evidence of effectiveness. However, trial results are not convincing and guaifenesin is probably little or no better than placebo. Given its proven safety record, absence of drug interactions, placebo properties and the public’s desire to treat productive coughs with a home remedy it would seem reasonable to supply OTC cough medicines containing guaifenesin.

Cough suppressants (antitussives)

Cough suppressants act directly on the cough centre to depress the cough reflex. Their effectiveness has been investigated in patients with acute and chronic cough as well as citric-acid-induced cough. Although trials on healthy volunteers – in whom coughing was induced by citric acid – allowed reproducible conditions to assess the activity of antitussives, they are of little value because they do not represent physiological cough. Of greatest interest to OTC medication are trials investigating acute cough, because patients suffering from chronic cough should be referred to the GP.

Codeine is generally accepted as a standard or benchmark antitussive against which all others are judged. A review by Eddy et al (1970) showed codeine to be an effective antitussive in animal models, and cough-induced studies in humans have also shown codeine to be effective. However, these findings appear to be less reproducible in acute and pathological chronic cough. More recent studies have failed to demonstrate a significant clinical effect of codeine compared with placebo in patients suffering with acute cough. Greater voluntary control of the cough reflex by patients has been suggested for the apparent lack of effect codeine has on acute cough.

Pholcodine

Pholcodine, like codeine, has been subject to limited clinical trials, with the majority being either animal models or citric-acid-induced cough studies in man. These studies have shown pholcodine to have antitussive activity. A review by Findlay (1988) concluded that, on balance, pholcodine appears to possess antitussive activity but advocates the need for better, well-controlled studies.

Dextromethorphan

Trial data for dextromethorphan, like that for codeine and pholcodine, are limited. It has been shown to be effective in citric-acid-induced cough and chronic cough but studies assessing the efficacy of dextromethorphan in acute cough have shown it to be no better than placebo. It appears to have limited abuse potential and fewer side effects than codeine.

Antihistamines

Antihistamines have been included in cough remedies for decades. Their mechanism of action is thought to be through the anticholinergic-like drying action on the mucous membranes and not via histamine. There are numerous clinical trials involving antihistamines for the relief of cough and cold symptoms, most notably with diphenhydramine.

Citric-acid-induced cough studies have demonstrated significant antitussive activity compared to placebo and results from chronic cough trials support an antitussive activity for diphenhydramine. However, trials that showed a significant reduction in cough frequency suffered from having small patient numbers, thus limiting their usefulness. Additionally, poor methodological design of trials investigating the antitussive activity of diphenhydramine in acute cough makes assessment of its effectiveness difficult. A recent review concluded ‘Presumptions about efficacy of diphenhydramine against cough in humans are not unequivocally substantiated in literature’ (Bjornsdottir et al 2007). Less-sedating antihistamines, have also not been shown to have any benefit in treating coughs compared to placebo (Smith et al 2008).

Demulcents

Demulcents, such as simple linctus, are pharmacologically inert and are used on the theoretical basis that they reduce irritation by coating the pharynx and so prevent coughing. There is no evidence for their efficacy and they are used mainly for their placebo effect.

Combination cough mixtures

Many of the over-the-counter cough preparations are combinations of agents. Some of these include ingredients targeting other aspects of a common cold such as decongestants. It should be noted that some combination products contain sub-therapeutic doses of the active ingredients, while a few contain illogical combinations such as cough suppressants with an expectorant, or an antihistamine with an expectorant. If possible, these should be avoided.

Summary

Antitussives have been traditionally evaluated for efficacy in animal studies or cough-induced models on healthy volunteers. This presents serious problems in assessing their effectiveness because support for their antitussive activity does not come from patients with acute cough associated with URTI. Furthermore, there appear to be no comparative studies of sound study design to allow judgements to be made on their comparable efficacy. Compounding these problems is the self-limiting nature of acute cough, which further hinders differentiation between clinical efficacy and normal symptom resolution.

Antitussives therefore have a limited role in the treatment of acute non-productive cough. Patients should be encouraged to drink more fluid and told that their symptoms will resolve in time on their own. If medication is recommended then any active ingredient could be selected; side effect profile and abuse tendency rather than clinical efficacy will drive choice. On this basis, pholcodine and dextromethorphan would be first-line therapy and codeine, because of its greater side effect profile and tendency to be abused, should be reserved for second-line treatment. Antihistamines should not be used routinely, unless night-time sedation is perceived as beneficial to aid sleep.

Cough medication for children

Very few well-designed studies have been conducted in children. A review published in the Drug and Therapeutics Bulletin (Anonymous 1999) identified just five trials of sound methodological design. However, of these five trials, one study used illogical drug combinations (expectorant combined with suppressant) and a further three studies used combination products not available on the UK market.

In 2008 a Cochrane review examining the treatment of acute cough in both adults and children concluded there was no good evidence to support the effectiveness of cough medicines in acute cough (Smith et al 2008). In addition, there has been growing evidence of the potential harm that these agents can pose to young children, either due to adverse effects, or from accidental inappropriate dosing (Isbister et al 2010; Vassilev et al 2010). Based on the lack of efficacy and potential harm, the MHRA/CHM (in 2008 and 2009 respectively) recommended that cough and cold mixtures should not be used in children under 6 years of age, and should only be used in children aged 6 to 12 on the advice of a pharmacist or doctor and treatment limited to 5 days or less.

Furthermore, in October 2010, the MHRA announced that the risks associated with OTC oral liquid cough medicines containing codeine outweigh the benefits in children and young people under 18 years and therefore should no longer be used.

Practical prescribing and product selection

Prescribing information relating to the cough medicines reviewed in the section ‘Evidence base for over-the-counter medication’ is discussed and summarised in Table 1.3; useful tips relating to patients presenting with cough are given in Hints and Tips Box 1.1.

Hints and tips box 1.1: Cough

Treatment for children under 6	Parents should be advised to make the child drink more fluid and potentially try a non-pharmacological cough mixture such as a demulcent.
Insulin-dependent diabetics	People with insulin-dependent diabetes should be asked to monitor their blood glucose more frequently because insulin requirements increase during acute infections
Avoid theophylline	Theophylline is available as an OTC product (e.g. DoDo Chesteze), but it is best avoided because patients requiring medication to help with shortness of breath or wheeze are best referred
Avoid illogical combinations	Very few cough remedies now have illogical medicine combinations. However, there are still a few on the market and these are best avoided. For example, combinations of expectorants and suppressants (e.g. Pulmo Bailey)

Table 1.3

Practical prescribing: Summary of cough medicines

^*Included in some cough preparations (e.g. Benylin Children’s Night Cough & Benylin 4 Flu).

Cough expectorants

Guaifenesin

Almost all manufacturers include guaifenesin in their cough product ranges, including Benylin, Robitussin and Vicks. Children aged between 6 and 12 years should take 100 mg four times a day and the dose for adults – if it is going to work – must be 200 mg four times a day. Some products deliver suboptimal doses or the quantity taken in a single dose would be so large that the product only lasts 1 or 2 days. It is therefore advisable to always check the label of any branded guaifenesin product before recommendation to ensure the patient is receiving appropriate treatment. Guaifenesin-based products have no cautions in their use and no side effects; they are also free from clinically significant drug interactions so can be given safely with prescribed medication. Sugar-free versions (e.g. Robitussin range) are available.

Cough suppressants (codeine, pholcodine, dextromethorphan)

Codeine, pholcodine and dextromethorphan are all opiate derivatives and therefore – broadly – have the same interactions, cautions in use and side effect profile. They do interact with prescription-only medications (POMs) and also with OTC medications, especially those that cross the blood-brain barrier. Their combined effect is to potentiate sedation and it is important to warn the patient of this, although short-term use of cough suppressants with the interacting medication is unlikely to warrant dosage modification. Care should be exercised when giving cough suppressants to asthmatics because, in theory, cough suppressants can cause respiratory depression. However, in practice this is very rarely observed and does not preclude the use of cough suppressants in asthmatic patients. However, other side effects can occur (e.g. constipation), especially with codeine. If a cough suppressant is unsuitable, for example in late pregnancy and children, then a demulcent can be offered.

Codeine

The dose for adults and children over 18 is 5 mL three or four times a day.

Pholcodine

The adult dose is 5 to 10 mL (5 to 10 mg) three or four times a day. For children aged 6 to 12 years the dose is half the adult dose, 2.5 to 5 mL (2.5 to 5 mg). Sugar-free versions (e.g. Pavacol-D) are available.

Dextromethorphan

Dextromethorphan can also be given in children over the age of 6. One product is commercially available (Vicks Cough Syrup with honey for dry coughs) – the dose being 5 mL every six hours. For adults and children aged over 12, there are a number of products available. (e.g. Benylin dry cough original and non-drowsy; Covonia original Bronchial Balsam and Robitussin for Dry coughs). The dosing is standard – 10 mL four times a day.

Antihistamines

Routine use of antihistamines is unjustified in treating non-productive cough. However, the sedative side effects from antihistamines can, on occasion, be useful to allow the patient an uninterrupted night’s sleep.

All antihistamines included in cough remedies are first-generation antihistamines and associated with sedation. They interact with other sedating medication, resulting in potentiation of the sedative properties of the interacting medicines. They also possess antimuscarinic side effects, which commonly result in dry mouth and possibly constipation. It is these antimuscarinic properties that mean patients with glaucoma and prostate enlargement should ideally avoid their use, because it could lead to increased intraocular pressure and precipitation of urinary retention.

Demulcents

Demulcents, for example simple linctus, provide a safe alternative for at-risk patient groups such as the elderly, pregnant women, young children and those taking multiple medication. They can act as useful placebos when the patient insists on a cough mixture and will not take no for an answer. If recommended they should be given three or four times a day.

References

Bjornsdottir, I, Einarson, TR, Guomundsson, LS, et al. Efficacy of diphenhydramine against cough in humans: a review. Pharm World Sci. 2007;29(6):577–583.

Eddy, NB, Friebel, H, Hahn, KJ, et al. Codeine and its alternatives for pain and cough relief. Geneva: World Health Organ; 1970. [1–253].

Findlay, JWA. Review Articles: Pholcodine. J Clin Pharm Ther. 1988;13:5–17.

Isbister, GK, Prior, F, Kilham, HA. Restricting cough and cold medicines in children. Journal of Paediatrics and Child Health. 2012;48:91–98.

Smith, SM, Schroeder, K, Fahey, T. Over-the-counter (OTC) medications for acute cough in children and adults in ambulatory settings. Cochrane Database of Systematic Reviews. 2008. [Issue 1. Art. No.: CD001831. DOI: 10.1002/14651858.CD001831.pub3].

Vassilev, ZP, Kabadi, S, Villa, R. Safety and efficacy of over-the-counter cough and cold medicines for use in children. Expert Opinion Drug Safety. 2010;9(2):233–242.

Background

Colds, along with coughs, represent the largest caseload for primary healthcare workers. Because the condition has no specific cure and is self-limiting with two-thirds of sufferers recovering within a week, it would be easy to dismiss the condition as unimportant. However, because of the very high number of cases seen it is essential that pharmacists have a thorough understanding of the condition so that severe symptoms or symptoms suggestive of influenza are identified.

Prevalence and epidemiology

The common cold is extremely prevalent and like cough is caused by viral URTI. Children contract colds more frequently than adults with on average five to six colds per year compared to two to four colds in adults, although in children this can be as high as 12 colds per year. Children aged between 4 and 8 years are most likely to contract a cold and it can appear to a child’s parents that one cold follows another with no respite. By the age of 10 the number of colds contracted is half that observed in pre-school children. In the UK, colds peak in December and January, possibly due to increased crowding indoors during cold weather, especially among schoolchildren.

Aetiology

More than 200 different virus types can produce symptoms of the common cold, including rhinoviruses (accounting for 30–50% of all cases), coronaviruses, parainfluenza virus, respiratory syncytial virus and adenovirus. Transmission is primarily by the virus coming into contact with the hands, which then touch the nose, mouth and eyes (direct contact transmission). Droplets shed from the nose coat surfaces such as door handles and telephones. Cold viruses can remain viable on these surfaces for several hours and when an uninfected person touches the contaminated surface transmission occurs. Transmission by coughing and sneezing infected mucus particles does occur, although it is a secondary mechanism. This is why good hygiene (washing hands frequently and using disposable tissues) remains the cornerstone of reducing the spread of a cold.

Once the virus is exposed to the mucosa, it invades the nasal and bronchial epithelia, attaching to specific receptors and causing damage to the ciliated cells. This results in the release of inflammatory mediators, which in turn leads to inflammation of the tissues lining the nose. Permeability of capillary cell walls increases, resulting in oedema, which is experienced by the patient as nasal congestion and sneezing. Fluid might drip down the back of the throat, spreading the virus to the throat and upper chest causing cough and sore throat.

Arriving at a differential diagnosis

It is extremely likely that someone presenting with cold symptoms will have a viral infection. Table 1.4 highlights those conditions that can be encountered by community pharmacists and their relative incidence.

Table 1.4

Causes of cold and their relative incidence in community pharmacy

Incidence	Cause
Most likely	Viral infection
Likely	Rhinitis, rhinosinusitis, otitis media
Unlikely	Influenza

Most people will accurately self-diagnose a common cold and it is the pharmacist’s role to confirm this self-diagnosis and assess the severity of the symptoms as some patients, for example the elderly, infirm and those with existing medical conditions might need greater support and care. In the first instance, the pharmacist should make an overall assessment of the person’s general state of health. Anyone with debilitating symptoms that effectively prevents them from doing their normal day-to-day routine should be managed more carefully. Whilst it is likely that a patient will have a common cold, severe colds can mimic the symptoms of flu, which is the only condition of any real significance that has to be eliminated before treatment can be given, although secondary complications can occur. Asking symptom specific questions will help the pharmacist to determine if referral is needed (Table 1.5).

Table 1.5

Specific questions to ask the patient: The common cold

Question	Relevance
Onset of symptoms	Peak incidence of flu is in the winter months; the common cold occurs any time throughout the year Flu symptoms tend to have a more abrupt onset than the common cold – a matter of hours rather than 1 or 2 days Summer colds are common but they must be differentiated from seasonal allergic rhinitis (hay fever)
Nature of symptoms	Marked myalgia, chills and malaise are more prominent in flu than the common cold. Loss of appetite is also common with flu
Aggravating factors	Headache/pain that is worsened by sneezing, coughing and bending over suggests sinus complications If ear pain is present, especially in children, middle ear involvement is likely