Duke Medicine: How to catch a cold

If you are plagued by a scratchy throat, stuffy nose, or cough this winter, you may have one of over 200 cold-causing viruses to thank for it. When it comes to determining how you caught that cold or how best to relieve your symptoms, the theories are almost as numerous.

Duke internist Sabina Lee, MD, explains the facts behind some common-cold related tips and advice that circulate during cold and flu season each year.

"The term 'common cold' refers to a mild upper respiratory viral illness involving sneezing, nasal congestion and discharge, sore throat, cough, low-grade fever, headache, and fatigue," Lee says.

Though cold viruses can be passed through the air, direct contact with a sick person is the most common form of transmission.

Here are some common ways people think they can catch a cold -- and debunk or confirm those ideas.

The risk of person-to-person transmission depends on the amount of time people spend together, their contact with one another, and the amount of virus shed by the infected person.

The viruses that cause colds can stay alive on human skin for up to two hours, so the closer you are to a sick person, the greater your risk of touching something contaminated.

If you avoid travel on airplanes because you worry that sharing air with strangers will get you sick, it’s safe to pack your bags.

Airplane passengers needn’t worry about the air they breathe, Lee says, as there is no medical research to back up the idea that breathing recirculated air increases your chances of getting sick.

This is just not true, says Lee. “Being in the cold temperatures will not give you an infection.”

However, she adds, if you are outside with someone who is sick you will be exposed to his or her germs, which increases your risk of infection.

These are more myths with no medical basis, says Lee. It’s hard to say, but this idea might be traced to a German scientist who found that World War I soldiers who slept in wet trenches were four times more likely to get sick than those who slept in dry barracks. However, a number of other studies have found that damp conditions have no effect on catching a cold.

Since viruses cause colds, there’s little that antibiotics will do to ease your suffering. More bad news, Lee says, is that despite widespread belief in a number of natural and over-the-counter remedies, there is little clinical evidence to back them up.

A persistent cough is one of the hallmarks of a bad cold. “Several popular ‘cough medicines’ have minimal, if any, efficacy and often produce significant side effects, especially in children,” Lee says.

Instead, she recommends honey, which is more effective than many cough medications and has far fewer side effects.

Research has shown that vitamin C, vitamin D, and North American ginseng may reduce the longevity of cold symptoms when taken preventively, but they do little to help once a cold has taken hold.

Since vitamin C doesn't have many side effects, making sure you get plenty of it throughout cold season may help to ward off future colds.

Echinacea studies vary tremendously (depending on what part or type of the plant is used), which makes it difficult to draw conclusive results from them, Lee says. While the jury is still out on whether Echinacea will cure you, since the plant has few adverse effects, increasing your intake probably won’t hurt.

Zinc is another common remedy that yields unclear results. Taking a high dose of zinc is usually fine for two to three days, but longer use is not recommended.

If you do take zinc, Lee cautions, take pill or lozenges. Several intranasal gels and sprays have been linked to irreversible anosmia (inability to smell) and should be avoided.

Whooping cough -- or pertussis -- has recently had a surge in frequency. Although it may begin with symptoms similar to the common cold, whooping cough causes coughing attacks associated with vomiting and sometimes apnea.

If you suspect you have whooping cough, or if your cold leads to ear or sinus infection, it may be time to talk to your doctor. Individuals with asthma and congestive heart failure should know that colds may aggravate those conditions as well.