Just pass the tissues… Evidence on remedies for the common cold

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 reviewsIn systematic reviews we search for and summarize studies that answer a specific research question (e.g. is paracetamol effective and safe for treating back pain?). The studies are identified, assessed, and summarized by using a systematic and predefined approach. They inform recommendations for healthcare and research. 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 treatmentSomething done with the aim of improving health or relieving suffering. For example, medicines, surgery, psychological and physical therapies, diet and exercise changes. 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 prevalenceThe proportion of a population who have a particular condition or characteristic. For example, the percentage of people in a city with a particular disease, or who smoke., 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?

Vitamin C

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 trialsClinical trials are research studies involving people who use healthcare services. They often compare a new or different treatment with the best treatment currently available. This is to test whether the new or different treatment is safe, effective and any better than what is currently used. No matter how promising a new treatment may appear during tests in a laboratory, it must go through clinical trials before its benefits and risks can really be known., involving 11,306 participants. Unfortunately, the review did not confirm Pauling’s findings. Taking regular Vitamin C did not reduce the incidenceThe number of new occurrences of something in a population over a particular period of time, e.g. the number of cases of a disease in a country over one year. of colds in the general populationThe group of people being studied. Populations may be defined by any characteristics e.g. where they live, age group, certain diseases., 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 riskA way of expressing the chance of an event taking place, expressed as the number of events divided by the total number of observations or people. It can be stated as ‘the chance of falling were one in four’ (1/4 = 25%). This measure is good no matter the incidence of events i.e. common or infrequent. 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.

Paracetamol

A 2015 Cochrane review of four randomizedRandomization is the process of randomly dividing into groups the people taking part in a trial. One group (the intervention group) will be given the intervention being tested (for example a drug, surgery, or exercise) and compared with a group which does not receive the intervention (the control group).   controlled trialsA trial in which a group (the ‘intervention group’) is given a intervention being tested (for example a drug, surgery, or exercise) is compared with a group which does not receive the intervention (the ‘control group’). (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 evidenceThe certainty (or quality) of evidence is the extent to which we can be confident that what the research tells us about a particular treatment effect is likely to be accurate. Concerns about factors such as bias can reduce the certainty of the evidence. Evidence may be of high certainty; moderate certainty; low certainty or very-low certainty.  Cochrane has adopted the GRADE approach (Grading of Recommendations Assessment, Development and Evaluation) for assessing certainty (or quality) of evidence. Find out more here: https://training.cochrane.org/grade-approach 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.

Antihistamines

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 placeboAn intervention that appears to be the same as that which is being assessed but does not have the active component. For example, a placebo could be a tablet made of sugar, compared with a tablet containing a medicine. (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.

Antibiotics

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.

Corticosteroids

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

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.

Steam inhalation

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 interventionA treatment, procedure or programme of health care that has the potential to change the course of events of a healthcare condition. Examples include  a drug, surgery, exercise or counselling.  .

Garlic

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.)

Vaccines

The Cochrane review (2017) which looked at the evidence for potential vaccines found only one studyAn investigation of a healthcare problem. There are different types of studies used to answer research questions, for example randomised controlled trials or observational studies. trialling a vaccine against adenovirus. There was no evidence of a difference between the vaccine and placebo in preventing the common cold.

In summary

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.

Honey

 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

 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.