Causes^[1]

The most important causes are:

• Coryza, ie the common cold.
• Hay fever: this is usually seasonal and predictable each year.
• Perennial rhinitis: this is rhinitis which occurs all year round and is usually due to allergy .
• Rebound congestion can occur when topical decongestant drugs are stopped. These are usually drugs like ephedrine or xylometazoline drops but can include abuse of cocaine.^[2]
• Nasal polyps are usually the result of chronic allergy or inflammation but they also result in persistent nasal discharge.
• Cerebrospinal fluid (CSF) rhinorrhoea is a rare but important cause which can follow a head injury. The meninges are torn and cerebrospinal fluid leaks down the nose. Ascending infection may cause meningitis.

Diagnosis^[1]

The diagnosis of each is based largely on the history.

• When was the onset?
• Is there pyrexia, aching or malaise suggesting infection?
• Is there a predictable periodicity as with hay fever? If it is perennial, does going away on holiday make any difference?
• Are there watery eyes or wheezing, suggesting allergy?
• What is the discharge like? It may be clear and watery, viscous, yellow or green or possibly blood-stained.
• Has the patient tried self-medication? If so, what and with what result? Look out for long-term use of topical decongestants.
• Note occupation and hobbies, especially if linked to a dusty environment.
• Young adults may need to be asked specifically about cocaine.

If there is not rapid resolution, examination is required as there may be unexpected findings, including polyps or foreign bodies. Good light and a nasal speculum are required.

Investigations

• Culture will guide any antibiotic therapy.
• X-ray of sinuses may show clouding from infection.
• Specialist investigation (eg CT scanning and screening tests for cystic fibrosis) may be required to rule out the rarer causes.

Management of specific clinical scenarios

Coryza^[3][4]

Coryza is an extremely common condition caused by a rhinovirus, although a number of other viruses may cause similar symptoms. The incubation period is 12 to 48 hours. Spread is usually by airborne droplets from person to person. The habits of children make them very likely to distribute it to each other and to adults. The virus has such a tendency to mutate that there is no effective immunity after infection and the virus can go round a family and reinfect the original subject as it has mutated again. The first features of infection are a sore throat and temperature of about 38°C or 39°C. Swollen lymph glands are common. There is malaise and myalgia in the early stages. An initial watery discharge becomes more viscous with time and then fades away.

Coughing and sneezing occur. Otitis media may well occur in children under the age of 5 and especially in those below the age of 18 months. In small children the angle of the Eustachian tube to the pharynx is less acute and so coughing and sneezing are more likely to project material into the middle ear. Secondary infection of mucus can lead to sinusitis and even bronchitis, especially when immunity is impaired by diseases such as cystic fibrosis or by smoking. Being exposed to cold, especially if core temperature drops, does predispose to the illness and the virus grows best in tissue cultures just below 37°C. The Cochrane library has produced about a dozen reviews related to the common cold and the following recommendations can be made:

• Routine antibiotics - these do not prevent the development of complications. However, if the mucus becomes foul and coloured and, especially of there is clinical deterioration, then antibiotics are probably of value.^[5]
• Antihistamines - in monotherapy these are ineffective in children or adults and first-generation drugs cause sedation. In combination with decongestants they are effective in older children and adults but not younger children. The significance of this benefit is unclear.^[6]
• Decongestants - it is poorly appreciated that pseudoephedrine can cause sleep disturbance in older children and adults and nightmares in young children. Decongestants, topical or oral, are of unknown benefit for those under the age of 12. A single dose in older children or adults appears beneficial but the effects of repeated doses are unclear.^[7] Topical decongestants should not be used for more than 5 to 7 days without a break or they become ineffective and, when they are stopped, there is rebound congestion. One study found that xylometazoline nose drops caused a rapid improvement in nasal congestion; this effect was even more marked when combined with ipratropium.^[8]
• Antivirals - benefit from antivirals has not been demonstrated. Attention should be directed to less specific antiviral agents as there may be a number of viruses that can cause the illness.^[9]
• Vitamin C - in 1978 the Medical Research Council's common cold unit at Porton Down (renowned for its work on biological warfare) concluded a large trial that showed that megadose vitamin C is of no value in preventing the illness or in hastening resolution. Since then the literature on the subject has been vast and has mainly confirmed the findings as laid out in a Cochrane review.^[10] One study in 2009 found that regular vitamin C consumption might decrease the duration of cold symptoms but did not affect symptom severity or act as a prophylaxis.^[11] Many of the public believe that vitamin C is beneficial and the fact that many commercial preparations sold to treat the symptoms of a cold contain vitamin C helps to maintain this belief.
• A review found that positively-charged ionised zinc can shorten the common cold by 6-7 days. The study involved lozenges delivering 18 mg of ionised zinc and taken two-hourly. Ionised zinc was found to be strongly astringent, antirhinoviral, increases interferon-gamma (IFN-gamma) 10-fold, inhibited intercellular adhesion molecule-1 (ICAM-1) and inhibited the release of vasoactive ingredients from mast cell granules. Previous studies had used both ionised and non-ionised zinc preparations and therefore gave mixed results.^[12]
• Echinacea - the results of trials in the early treatment of colds in adults show some benefit but are inconsistent. There are no rigorous trials supporting its use in prevention.^[13] One study found an inhibitory effect on the activity of several commonly occurring respiratory bacteria including Haemophilus influenzae and Streptococcus pyogenes.^[14]

Persistent nasal discharge

This may be caused by allergy or infection but the constant production of excessive mucus predisposes to infection that may perpetuate the condition. Again a Cochrane review has examined the evidence. The conclusion was that in children with persistent nasal discharge or older children with radiographically confirmed sinusitis, antibiotics given for 10 days will reduce the probability of persistence in the short- to medium-term. The benefits appear to be modest and around 8 children must be treated in order to achieve one additional cure (number needed to treat (NNT) 8, 95% confidence interval (CI) 5 to 29). No long-term benefits are clear.^[15] There are a small number of small randomised controlled trials and further data may change the opinion. One such trial identified a subset of children who were likely to benefit, viz: those with predisposing factors, such as recurrent respiratory tract infections, allergic rhinitis, cystic fibrosis, immunodeficiency, ciliary dyskinesia, anatomic abnormalities or reflux. Amoxicillin was recommended as the first-line choice for mild cases, with an antibiotic that can deal with all possible resistent infections for severe cases.^[16]

Guidelines on the management of rhinosinusitis and nasal polyposis have been released by the British Society for Allergy and Clinical Immunology (BSACI). The available evidence suggests that treatment should be primarily medical, involving douching, corticosteroids, antibiotics, anti-leukotriene and antihistamines. Endoscopic sinus surgery should be reserved for complications, anatomical variations causing local obstruction, allergic fungal disease or patients who remain very symptomatic despite medical treatment.^[17]

Persistent nasal discharge can produce a postnasal drip (PND) that causes a chronic cough or even hoarseness from dripping down on to the vocal cords. Because it is unclear whether the mechanisms of cough are the PND itself or direct irritation or inflammation of the cough receptors located in the upper airway, there has been a recent move by respiratory physicians to replace the term PND with the term upper airway cough syndrome when discussing cough associated with upper airway conditions.^[18]

Allergy

Nasal discharge is often a feature of allergic phenomena. Allergic rhinitis may be seasonal, often due to pollen, or perennial, often due to the house dust mite. The 'summer cold' is often really hay fever. Treatment may consist of an antihistamine, preferably of a non-sedating nature or topical steroid or cromoglicate preparations. Congestion of the nasal mucosa can lead to nosebleeds.

Nasal polyps may also develop, leading to constant discharge, obstruction and anosmia.^[19] They may also lead to snoring or stuffy nose and nasal obstruction. The catarrhal child is likely to have impaired hearing with possible delay of speech and social delay.^[20] Hearing tests and screening in young children are important if there is cause for concern. Chronic suppurative otitis media may develop. Inflammation may also block the drainage ducts of the sinuses and cause acute sinusitis.^[21]

Less common causes

• Nasal injury and foreign bodies should not be forgotten. Small children push things into their noses and this may present as a foul and chronic discharge.^[22] In older patients there may even be unexpected lesions like a basal cell carcinoma.^[23]
• Wegener's granulomatosis is a rare condition that can present with nasal discharge, usually between the ages of 30 and 50.^[24]
• CSF rhinorrhoea implies fracture of the cribriform plate. There is a clear discharge of CSF that tests positive for glucose. A glucose oxidase stick can be used. CT scan and referral to a neurosurgeon are required.^[25]