Quiz: The Truth About the Common Cold

A lot depends on which virus you're dealing with. They can also survive for that long on things like your kitchen counter and that doorknob your preschooler just touched after wiping his nose without a tissue. If someone in your house has a cold, wipe surfaces with a virus-killing disinfectant.

Colds spread most easily before your symptoms start and during the first 2-4 days after they begin. You don't have to hide in a bubble, but try to avoid close contact with others when you're sick, and wash your hands frequently. Cover your mouth with a tissue when you sneeze or cough -- or use the crook of your elbow. (You don't usually touch people or objects with your elbow, so you're less likely to spread germs than if you cover your mouth with your bare hand.)

There are more than 200 viruses that can give you a cold. The most common is rhinovirus, which accounts for 50%-80% of common colds. Antibiotics don't work against viruses (only bacteria). Using them to treat a cold not only doesn't help but they may cause side effects.

"Don't go out with that wet head, you'll catch your death of cold!" Despite your mom's warnings, it doesn't put you at greater risk. You might feel chilled and uncomfortable, but colds are spread by germs, not the temperature.

Colds are spread by close contact, and in the winter we spend a lot more time inside, keeping warm. That means we're more exposed to other people -- and their germs. Winter air is also much drier than the air in spring and summer, and cold viruses tend to thrive in low humidity. (Running a humidifier in your bedroom during the coldest winter months can help with cold symptoms.)

Some people swear by Vitamin C. But there is very little proof that Vitamin C has any effect on preventing the common cold. However, a large analysis of studies showed that patients taking Vitamin C every day (at least 200 mg/day) had a small reduction in how long their colds lasted.

Reviews of studies of echinacea's effectiveness in fighting colds suggest the herbal extract may help prevent cold symptoms but does not shorten the duration of the illness. 

The best remedy for him is an old-fashioned one: Stay in bed and get plenty to drink. Don't give over-the-counter cold and cough medications to children under age 4. There's no evidence that these medicines help children. Any possible benefits are not worth the risk.

It helps break up your stuffy nose. Some studies suggest that it curbs the inflammation that leads to a sore throat. And when you're feeling run-down, the combination of lean protein and vegetables can help boost your strength to fight off illness.

Here's how to do it right: Wet your hands first, then apply soap, and scrub for at least20 seconds. That's how long it takes you to sing the "Happy Birthday" song twice. Hand sanitizers can also be a good supplement to regular handwashing.

Kids get between 6 and 10 colds every year -- including spring and summer -- so it's not unusual for your child to be sniffling and sneezing every other month, or even more often. If he's in day care, preschool, or another setting where he spends a lot of time with other kids, he'll get exposed to lots of germs.

Some people do run a slight fever along with a cold, but if you have a high temperature it's more likely the flu or a complication. Fatigue, while more common with the flu, also happens with colds.

It's not just your yoga teacher trying to persuade you to take another class: Studies show that people are more likely to catch a cold when they're under stress. You may be more vulnerable to getting sick if you face stress that lasts more than 1 month, like trouble at work or problems in your family relationships. And if stress is stealing valuable sleep, you're likelier to catch a cold. 

Mucus during a cold is usually clear or light yellow, but it can change to thick yellow or green-tinged mucus. This suggests the complication of rhinosinusitis, where the cold virus inflames the nasal passages and sinuses. You may also have nasal obstruction, facial pain, and headaches. Rarely, green-tinged mucus during a cold is caused by bacteria. 

It only protects you from the virus that causes the flu. Scientists are trying to create a vaccine for the common cold, but it's a tough job because there are hundreds of viruses that can cause one. It probably will be many years before any vaccine is effective against colds.