It’s that time of year again – colds and flu are everywhere. But how much do we really know about them?

What causes a cold?

The common cold is caused by any of a number of viruses that can involve the upper respiratory tract. As your body reacts against the attacking virus, you get the symptoms of a cold -- including nasal congestion, sneezing, and sniffle.

What about the flu?

Influenza, or "the flu," is caused by one of several strains of the influenza virus. These viruses usually cause symptoms in the head and chest -- such as congestion, sore throat, or cough -- but also can cause intestinal symptoms such as nausea and vomiting. The influenza virus also can cause general symptoms such as fever, muscle aches, chills, or sweats.

Are people with strong lungs less susceptible to a cold or the flu?
Regular exercise, from aerobics to walking, boosts the immune system. People who exercise may still catch a virus that causes a cold or the flu, but they may have less severe symptoms and may recover more quickly than their friends who do not exercise.

Are people who have asthma or allergies at greater risk for catching a cold or flu? Yes. People who have asthma or allergies may already have inflamed and irritated lungs. If so, and if their bodies are already fighting one irritant or illness, it is more difficult for them to fight off a virus. Smokers are also more likely to have irritated lungs and are more likely to catch a cold or the flu.

Are you contagious before you show symptoms? If a co-worker is sniffing over the phone you share, is he or she contagious then?
The viruses that cause colds and the flu are spread by microscopic droplets from an infected person's respiratory system. It may be possible to catch the virus before symptoms show, via close contact such as kissing or sharing eating utensils. However, in general people need to have some symptoms, such as a runny nose or cough, in order to be contagious.

When your co-worker shows symptoms, he or she may indeed be spreading contagious droplets to your shared phone, to the doorknob of your office, etc. Your best defense is to wash your hands frequently. Why do young children always seem to have a cold? There are several reasons children catch colds so often. In day care and school they come in contact with lots of people, children and adults, who may be carrying a virus. Children don't always have good hygiene: They may wipe their noses with their hand instead of using a tissue, they may cough and forget to cover their mouth, or they may not wash their hands unless reminded. Also, adults have had longer to develop immunities to certain viruses. Children develop immunities to viruses only as they come in contact with them.

Should you starve a fever and feed a cold? You can treat both about the same. Make sure you are drinking fluids. In fact, drink more than usual. Avoid drinks that will rob your system of fluids, such as coffee, teas, and colas with caffeine. As for eating, use your appetite as a guideline. If you're not particularly hungry, try to eat some simple foods like white rice or broth. If you feel like eating a steak, go ahead!

How effective are home remedies such as a hot toddy or chicken soup? Like many cold remedies, a hot toddy or chicken soup might soothe your sore throat and help you sleep. However, there's no proof that either will drive the virus out of your body.

Can you catch cold by going out in the cold air or getting a chill? No. You need to be exposed to the virus (usually in the form of respiratory droplets from someone near you) in order for you to contract it. It is possible that cold air can irritate an existing condition, such as asthma. This may make your body more receptive to the virus, but only if you come in contact with it.

How effective are natural remedies such as Zinc, Echinacea, and vitamin C? In some individuals, natural remedies and preventive measures seem to help. However, researchers have not proved that these things can prevent a cold or the flu, reduce symptoms, or rid a body of a virus.