Next time you catch a nasty cold, you may want to skip the ginseng, Chinese medicine, homeopathy or mega-doses of vitamin C. A large review of studies looking at treatment and prevention of the common cold found little evidence that alternative remedies do any good.
There's a chance that zinc may shave a day off your cold, however – if you can stomach swallowing a zinc lozenge every two hours.
But the evidence even for zinc remains shaky, said co-author Dr. Michael Allan, a professor of family medicine at the University of Alberta and co-author of the report, published Monday in the Canadian Medical Association Journal.
"I don't think it's strong enough for me to prescribe it yet," Allan said, "but it's a reasonable bet that zinc might work."
Zinc treatment for colds does not appear to work in children, he added. But Allan and co-author Dr. Bruce Arroll of the University of Auckland, New Zealand, found that taking zinc sulphate daily was "likely beneficial" in preventing colds in kids, although they noted a high risk for bias in corresponding studies.
The case for honey as a cough treatment is stronger, Allan said. The researchers found that taking a spoonful of honey near bedtime reduced coughs in children – and helped kids and parents get more sleep.
Although no research was done on adults, three studies on children had nearly identical results, Allan said: "Honey certainly seems to reduce coughs in young children." But he added that honey is not recommended for babies under 12 months because of the risk of botulism.
Other than zinc and honey, cold sufferers have limited options for prevention and treatment, Allan said.
The CMAJ review confirmed that the only proven way to prevent colds is hand-washing, or using an alcohol-based hand disinfectant.
The researchers found some evidence that probiotics may help prevent upper respiratory tract infections, but noted that studies used different organisms and formulations of probiotics (pills and liquids), making it difficult to determine which probiotics actually worked.
Five trials of the Cold-FX brand of North American ginseng showed no significant reduction in colds. Seven trials found that vitamin C was an ineffective treatment for colds. Other go-to remedies, including gargling, vapour rubs, echinacea, humidified air, homeopathy and nasal irrigation with a Neti pot, were of "unclear benefit" because findings were inconsistent and studies were poorly designed, the authors wrote.
Cold medications containing antihistamines with decongestants and/or pain medications show moderate benefit in treating colds in adults and older children – but not in kids under 5. Nasal sprays with ipratropium, a drug used to treat allergies and chronic obstructive pulmonary disorder, may help a runny nose but not congestion, the authors concluded.
Not surprisingly, ibuprofen and acetaminophen reduce pain and fever, but ibuprofen appears better for fever in children, the authors found.
Antibiotics may be the worst treatment for colds overall. Not only are they ineffective, Allan said, but they also carry the risk of diarrhea and allergy in children and adults, and may trigger rashes in kids.
"There is absolutely no reason to use antibiotics in something you suspect is the common cold," he said. Allan noted that some individuals may respond better to an alternative treatment than others, and noted the power of the placebo effect. If a patient has a remedy they swear by, such as ginseng, "I'm not going to talk them out of it," he said.
But the only evidence-based treatments for the common cold include rest, liquids, analgesics for pain or fever and a spoonful of honey for coughs.
"That's all there is," Allan said.