The prevention and treatment of viral respiratory disorders
A briefing from the Board of Science
September 2007
Symptom-relief
While it is possible to get immunised against particular viruses by vaccination, the huge number of different viruses that cause the common cold make it almost impossible to ensure complete protection.There are a number of effective treatments which, rather than treating the viral infection, focus on relieving the symptoms. The most reliable treatment is a combination of fluids and plenty of rest; relieffrom symptoms however, allows more comfortable recovery.
A number of steps can be taken in order to alleviate the symptoms of the common cold and influenza. These include a warm and humid environment and high fluid intake, especially hot liquids. There are also a number of pharmaceutical treatments and home remedies.
Medication
There are a wide variety of pharmaceuticals available which treat the symptoms of the common cold, these include:
- analgesics – such as paracetamol, ibuprofen, codeine or aspirin (children under 16 should not take aspirin, as doing so during a viral infection increases the risk of developing Reye’s syndrome)39
- throat lozenges – typically contain ingredients with analgesic, anaesthetic or antiseptic activity
- decongestants – such as pseudoephedrine and phenylephrine reduce the inflammation in the nasal passages by constricting local blood vessels. Decongestant nasal sprays should not be used for longer than a week. After that, they can cause rebound congestion, meaning a return of congestion after stopping use [see reference 40]
- cough suppressants – such as dextromethorphan work to suppress the cough reflex of the brain or by diluting the mucus in the lungs
- first-generation anti-histamines and anti-cholinergics – such as diphenhydramine and dicyclomine reduce mucus secretion and thus combat blocked/runny noses but also may make the user drowsy. [see reference 41]
While there is little scientific evidence behind the majority of home remedies, many have some basis in medical or scientific theory, as to their effects. Some examples of such remedies include:
- warm drinks – chamomile, herbal infusions, hot toddies etc. These work by soothing the irritated respiratory passages with their steam and soothing sore throats with their liquid heat
- spicy foods – mustard, curry, chillies etc. These can alleviate congestion, although they may also irritate an already tender throat
- steam inhalation – breathing hot air exposes the virus to excessive heat, which kills the rhinovirus as it cannot survive at elevated temperatures for more than a few minutes. It is also believed that breathing steam may help to loosen mucus in the nose and lungs so that it can be removed by coughing
- gargling with salt water – reduces inflammation of the throat and nasal tissue, helping to reduce irritation and ease breathing
- vitamin C – may both prevent and reduce the effects of the common cold when administered in large doses. Research showed that vitamin C reduced the incidence of colds by 50 per cent in six trials with physically stressed participants, and that regular vitamin C supplementation shortened the duration of colds in children by 14 per cent and in adults by eight per cent. [see reference 42] Recent evidence however, suggests that this may only be true of large doses of vitamin C if at all [see reference 43]
- Echinacea – this is a herbal remedy commonly used to ward off colds. Some studies have shown that it helps with cold symptoms, but others found that it does not help at all. Most of the studies were of poor quality, however and therefore unreliable [see reference 44]
- research has shown that chicken soup, which has long been used as a remedy for symptoms of the common cold, can slow the activity of certain white blood cells (neutrophils). This is thought to lead to an anti-inflammatory effect which could temporarily ease the symptoms of illness [see reference 45]
- other home remedies include hot compresses, liquorice, caffeine, menthol and lemon.
- sinus pain
- shortness of breath or painful breathing
- a sore throat that does not improve after four or five days
- pain around the neck glands
- discoloured or bloody discharge from the nose or throat
- persistent or worsening cough
- severe headache
- a fever over 100ºF (38ºC) for more than four or five days.