It's that time of year again! We're counting our sick days, stockpiling over-the-counter immunity boosters and washing our hands like maniacs. We spoke to Dr. David White, associate professor of family and community medicine at the University of Toronto, to help us sort out what works and what doesn't when it comes to the common cold and flu.

1. Vitamin C boosts immunity
The belief: It is long-held popular opinion that taking daily doses of vitamin C will help prevent the development of a cold or flu.

The truth: Dozens of clinical trials on the subject have been conducted with relatively inconclusive results for the average adult, meaning the jury is still out on this natural remedy. But a recent study has shown physically active people under heavy physical stress (athletes and soldiers in extreme cold) seem to benefit from a supplementation of the vitamin, with a 50 percent reduction in cold occurrences among participants.

2. Echinacea speeds up your recovery
The belief: Derived from a native Indian medicinal plant, this herbal supplement is thought to shorten the duration and lessen the severity of the common cold and flu when taken at the onset of symptoms.

The truth: There is very little scientific research to support the efficacy of the centuries-old cure-all. "It's popular, it's probably not harmful, and people often use it to both prevent and treat colds, but echinacea falls more into the category of not proven to be effective," says White.

3. Steam soothes symptoms
The belief: Using water vapours – either from a hot shower, a room humidifier or a steam pot – will provide relief from congestion.

The truth: "Humidification is important and it's a very natural way to make yourself feel better," says White. "It's not a cure but it helps you cope with your symptoms and to keep up the fluids internally, which is helpful for both colds and fevers."

4. Zinc kills colds
The belief: Taking zinc, an essential mineral, as a supplement will help shorten the lifespan of a cold.

The truth: A study published in 2012 showed that when high doses of zinc were taken orally, the duration of symptoms in adult patients was reduced. But participants were also more likely to suffer from adverse effects such as nausea, and the quality of the evidence was only moderate.

5. A magic pill exists
The belief: There are over-the-counter products that will stop a virus in its tracks.

The truth: "Be pretty cautious about extravagant claims of things that are thought to prevent or cure colds," says White. "The viruses themselves change pretty regularly, so it's hard to see how one particular remedy would be across-the-board effective against a whole range of viruses that cause things that we call colds." For true influenza, however, the best preventative measure is to get the flu shot; it will effectively protect you and the at-risk people you come in contact with.

6. Cold weather makes you sick
The belief: If you head outside with wet hair, accidentally get your feet wet or forget to wear a hat on a cold winter day, you will "catch" a cold or flu.

The truth: "Without a virus, you can't get sick, but there are always some truths to those myths," says White. "Canadian winters are cold and dry, which is tough on your mucus membranes. It may just be harder for them to function and we may be more susceptible to viruses because of that reason, so there could be an association between the two, but it's not a direct cause."

7. Feed a cold, starve a fever
The belief: As the old saying goes, your best defence against a cold is to stay nourished, while fasting puts an end to the flu.

The truth: "It's not true in the literal sense," explains White. "In general, if we're sick enough to have a fever, we don't feel much like eating anyway. The main thing with both colds and [the] flu is to keep your fluids up. You want to stay hydrated." Up your intake of H2O as well as warm liquids, like chicken soup or tea with honey and lemon, which help soothe an aching throat.

8. Stress makes you vulnerable
The belief: Burning the candle at both ends is an open invitation for a rhinovirus to take hold.

The truth: White confirms there is strong statistical evidence supporting the claim that people who are stressed or sleep deprived are more likely to get both bacterial and viral infections. "There have been studies that show people who rate their stress higher and are exposed to a virus are more likely to contract it," he says. Rest up and practise relaxation techniques – taking care of yourself is the best defence against viral infections. 

For cold and flu treatments that are proven to work, try these five natural remedies.