In a blog for non-medical readers, Lynda Ware, Senior Fellow in General Practice with Cochrane UK, gives a round up of twelve Cochrane systematic reviews on remedies for the common cold. Now with additional evidence for winter 2018.
It’s that time of year again – coughs and sneezes spreading diseases – and widespread snotty misery prevails. Myths and old wives’ tales abound about how best to prevent and treat the common cold. We have probably all tried most of them: feeding colds and starving fevers, hot honey and lemon, hot toddies, echinacea, vitamin C, paracetamol, decongestants up the nose or into the mouth, steam inhalations (did your mother stick you over a bowl of steaming hot water with a towel draped over your head? – so embarrassing), vapour rubs – the list goes on.
Remembering that nothing really made that much difference leads neatly to this overview of twelve Cochrane systematic reviews on the treatment and prevention of the common cold. And, sad to relate, nothing much has changed.
The common cold is viral in origin with over 200 viruses potentially laying claim to being involved. The rhinovirus is the commonest cause. The illness is usually self-limiting, with symptoms typically lasting one to two weeks, but it can lead to significant time off work and school, as well as using up doctors’ appointments. It is characterised by a runny nose, sore throat, congestion, cough, malaise and sometimes mild fever. On average adults may get 2-4 colds per year and young children as many as 6-8. A quoted statistic is that half a billion adults in USA alone experience common colds every year – that’s a considerable number of paper tissues!
Despite its prevalence, a cure for the common cold has eluded medical science and treatment is aimed at relieving symptoms. There is also no foolproof way of preventing it either.
What did the Cochrane reviews look at?
There was great excitement in the 1970s when Linus Pauling, (a Nobel laureate twice over), concluded from placebo-controlled trials that Vitamin C could prevent and alleviate the common cold. Further research followed and a Cochrane review, published in 2013, found 29 clinical trials, involving 11,306 participants. Unfortunately, the review did not confirm Pauling’s findings. Taking regular Vitamin C did not reduce the incidence of colds in the general population, although there was a modest reduction in the duration and severity of symptoms.The only people who appeared to derive some benefit were those who undertook short bursts of extreme exercise, such as marathon runners and skiers. In this group the risk of getting a cold was halved.
Trials looking at taking high dose Vitamin C at the onset of cold symptoms showed no consistent effect on the duration and severity of symptoms and more research is needed to clarify these findings.
Oral antihistamine / decongestant / analgesic combinations
These combination preparations are widely available over-the-counter (OTC) in pharmacies and supermarkets. A Cochrane review from 2012 (27 trials, 5117 participants) concluded that they have some general benefit in relieving symptoms and aiding recovery in adults and older children. The most effective combination is an antihistamine/decongestant combo but the benefits must be weighed against side-effects such as drowsiness, dry mouth, sleep disturbance and dizziness.
A 2015 Cochrane review of four randomized controlled trials (RCTs) with 758 participants concluded that paracetamol may relieve nasal obstruction and runny nose but it does not appear to help other symptoms such as sneezing, sore throat, cough and malaise. The quality of evidence in the included trials was low to moderate and further high-quality studies are needed to determine more confidently just how effective paracetamol really is in providing symptom relief.
Non steroidal anti-inflammatory drugs (NSAIDs)
A 2015 Cochrane review (9 RCTS, 1069 participants) concluded that NSAIDs help pain symptoms but not really much else and of course are associated with side-effects such as irritation of the stomach lining.
45% of the participants taking antihistamines (Cochrane review 2015, 18 trials, 4342 participants) found that the severity of overall symptoms was improved short-term compared to 38% of participants taking placebo (a dummy tablet). This difference was no longer evident from day 3 onwards and there was an increased risk of side-effects such as sleepiness.
Common colds are caused by viruses, which are unaffected by antibiotics. A Cochrane review (2013) looked at the use of antibiotics in the treatment of colds and purulent rhinitis. Perhaps not surprisingly, antibiotics were not shown to be effective and were associated with side-effects.
Nasal decongestants used alone
Multiple doses of nasal decongestant may help a little with nasal congestion (Cochrane review 2016) but it was unclear whether this actually was of benefit to the patient. It is important not to exceed the recommended dosing schedules.
These drugs act as powerful anti-inflammatory agents in other upper respiratory infections but current evidence (Cochrane review 2015) does not support the use of intranasal corticosteroids to relieve the symptoms of the common cold. However, there were only three trials included in the review. Further high quality research is needed.
Echinacea is widely used in Europe and North America for common colds. A Cochrane review (2014) showed that some Echinacea products may be more effective than placebo in treating colds but the overall evidence for clinically relevant effects was weak. There was some evidence of a small preventative effect.
Inhaled steam has been used for decades (see earlier reference to my childhood humiliation!) thinking that it helps drain away mucus more effectively and possibly destroys the cold virus. A Cochrane review (2017) of six trials with 387 participants showed no consistent benefit for this intervention.
A single trial with 146 participants showed that taking garlic every day for three months might prevent occurrences of the common cold but the evidence was of low quality and more research is needed to validate this finding. (Cochrane review 2014.)
The Cochrane review (2017) which looked at the evidence for potential vaccines found only one study trialling a vaccine against adenovirus. There was no evidence of a difference between the vaccine and placebo in preventing the common cold.
As things stand, we are destined to continue to suffer from colds. There is as yet no effective vaccine available and no conclusively proven preventative measure that can help keep us immune.
OTC antihistamine and decongestant preparations taken alone or in combination may help a little in relieving symptoms.
Otherwise, its down to common sense …… and pass the tissues.
For winter 2018, there’s more news…
Since posting this blog two interesting reviews have been published on the effects of honey and Vitamin D in relieving or preventing the common cold.
A Cochrane systematic review was published in April 2018 looking at the effects and harms of honey in helping relieve cough in children.
The review shows that honey is probably effective in relieving cough symptoms and may be as effective as OTC preparations. A simple remedy our grandmothers would endorse. You can read more in my blog here.
Vitamin D is best known for its effect on calcium metabolism and for keeping our bones healthy. It would appear to have benefits in preventing the common cold as well. Prof. Adrian Martineau led a team of authors of a systematic review published in the BMJ in 2017, which investigated the effect of Vitamin D on upper respiratory infections (URTIs). The review concluded that there is high certainty evidence that vitamin D supplements help prevent URTIs, especially in those who have a deficiency.
Public Health England recommends that we take a Vitamin D supplement in the winter months since we see little sunshine – a crucial factor in the production of Vitamin D. It now seems that this advice comes with bonuses…!
References may be found here.
Lynda Ware has nothing to disclose.
Page last updated: 20 November 2018.