Zinc supplements and soap may be the best answer to the common cold, say experts.
New research suggests that when it comes to avoiding sniffles, simple solutions are not to be sneezed at.
A review of 67 randomly controlled trials (RCTs) indicated that washing hands was one of the most effective ways to keep colds at bay.
At least two studies also showed that zinc helped protect children, and may work for adults too.
Children who took a daily supplement of 10 or 15 milligrams of zinc sulphate had lower rates of colds and fewer sick days off school.
There was also some evidence that probiotics, which boost numbers of friendly bacteria in the gut, may help prevent colds.
On the other hand, the idea that taking vitamin C can stop you having a cold appeared to be a myth, according to the evidence.
The findings, from doctors Michael Allan, from the University of Alberta in Canada, and Bruce Arroll, from the University of Auckland, New Zealand, appear in the Canadian Medical Association Journal.
“Although self-limiting, the common cold is highly prevalent and may be debilitating,” the authors wrote. “It causes declines in function and productivity at work and may affect other activities such as driving..
“Much more evidence now exists in this area, but many uncertainties remain regarding interventions to prevent and treat the common cold. We focused on RCTs and systematic reviews and meta-analyses of RCTs for therapy, but few of the studies had a low risk of bias. However, many of the results were inconsistent and had small effects (e.g., vitamin C), which arouses suspicion that any noted benefit may represent bias rather than a true effect.”
Little can be done to treat the common cold, but the research suggested that antihistamines combined with decongestants and/or pain medication may be effective in adults and older children.
Pain and fever could be alleviated with drugs such as ibuprofen and paracetamol.
The benefits of other remedies such as ginseng, gargling, vapour rubs and homeopathy remained “unclear” said the researchers.
Honey had a slight effect in relieving cough symptoms in children older than one. But vitamin C and antibiotics showed “no benefit”.
Graham Keen, executive director of the Health Food Manufacturers’ Association (HFMA), said: “This new review contradicts pre-existing, robust evidence demonstrating a positive impact of vitamin C supplements in this area.
“For example, a large-scale Cochrane meta-analysis published in 2013 found that regular vitamin C supplementation seems to have a consistent effect in reducing the duration and severity of common cold symptoms.
“It is also important to note that these products are not designed for curing or preventing the spread of disease. Daily vitamin supplements provide important nutritional insurance for millions of users looking to safeguard their nutritional intake alongside a healthy diet.”