Now, a new review finds that some methods seem to work better than others, namely hand washing and zinc supplements for prevention of a cold, and decongestants and pain relievers for treatment.
For preventing colds, frequent hand washing came out on top, said study leader Dr. Michael Allan, director of evidence-based medicine in family medicine at the University of Alberta, in Canada.
Besides hand washing, daily zinc supplements appeared to help kids avoid colds, some research found, and Allan said it would probably work for adults. The evidence was not strong, however.
"It wouldn't be something I'd recommend on a regular basis," he said. Zinc use can lead to nausea and has an unpleasant taste, he noted.
For the study, Allan's team reviewed hundreds of published studies looking at the best ways to prevent and treat colds. The review is published in the Jan. 27 issue of CMAJ (Canadian Medical Association Journal).
Some evidence also suggests that probiotics -- the "good bacteria" found in some yogurts and elsewhere -- helped prevent colds. However, the studies included various combinations of probiotics, so making comparisons about which is best was difficult, Allan said.
For the prevention of colds, the evidence wasn't clear for gargling with water (and no benefit was found from gargling with an iodine solution), ginseng, exercise, garlic, homeopathy, echinacea or vitamins C or D.
For the treatment of colds, antihistamines by themselves didn't help. But they did help somewhat when used in combination with decongestants, pain relievers or both -- but only in children over age 5 and adults. For fever in kids, he said, parents can use acetaminophen or ibuprofen, "but ibuprofen is superior to acetaminophen; it's a more potent fever reducer."
Nasal sprays with ipratropium (Atrovent) -- prescribed for allergies and other conditions -- may help runny noses but don't seem to help congestion, Allan found.
For the cough associated with cold, children over the age of 1 who get a single dose of honey at bedtime had reduced cough, Allan said. Honey should not be given to children younger than 1 due to risk of botulism poisoning.
Many other old favorite treatments fell short, Allan found. Vapor rub was linked with burning of skin, eyes and nose. No clear benefit was found for nasal irrigation, humidified air, echinacea, Chinese medicinal herbs, ginseng or vitamin C. Intranasal zinc spray should not be used, Allan said. It has no clear benefit and could lead to loss of smell.
Even without evidence of benefit, Allan said many of his patients swear by the remedies that have helped them in the past. As long as they present no harms, he tells them to go ahead.
"People have individual reactions to medicines that are not predictable," he said. "There is also, of course, the placebo effect -- you think it's going to work [and you feel better]."
The finding that hand washing is the best preventive rings true, said Dr. Aaron Glatt, a spokesman for the Infectious Diseases Society of America and executive vice president of Mercy Medical Center, in Rockville Centre, N.Y.
Most treatments for the common cold, Glatt agreed, have minimal benefits. Whatever cold remedy is chosen, he added a caveat: "If you have an underlying disease, see a doctor to be sure there are no complications."
For example, anyone with heart or lung disease should be aware a cold may impact them more strongly than others. "Those types of patients should check in with their doctor," Glatt said.
Visit the American Academy of Pediatrics for more on colds in kids.