Nobody wants the common cold as a guest, but the upper respiratory infection keeps knocking at the door, never more frequently than during the winter holiday season.

Some experts have suggested it offers a service in building up a child’s general immunities. Bah, humbug to the cold bug on that, responds Dr. Jeffrey Kahn, director of infectious diseases in the department of pediatrics at University of Texas Southwestern Medical Center.

“I would not favor exposing young infants to respiratory viruses as this can lead to lower respiratory tract diseases like pneumonia and upper respiratory tract infections, which often lead to otitis media (ear infections), which can be serious and lead to increased use of antibiotics — not good,” Kahn said. “While I agree that there may be a prevailing germ phobia in our culture and not all microbes are bad, I would not put the cold viruses in this category.”

That said, here’s a look at common myths and how best to prevent and fight colds, according to Kahn and to Dr. Amber Hyde, an independent primary care physician at Methodist Mansfield Medical Center in Dallas; Dr. Paul Kim, a family practitioner associated with Baylor Regional Medical Center at Grapevine; and Dr. Janna Massar, an internist associated with Texas Health Presbyterian Hospital Plano.

• Colds are caused by cold weather.

No, they are caused by viruses. However, you might be more susceptible to colds in the winter months because you tend to go indoors in crowded environments where you are more likely to pick up other people’s viruses. Plus, there are some strains of cold viruses that thrive in the cold, and cold weather can dry out your sinuses, making them more vulnerable to infection.

• The best cure is vitamin C.

No, there’s no proof that vitamin C helps, but vitamins C and B-12 have fans among medical professionals, and they can’t hurt.

Some experts strongly recommend zinc lozenges, but because of divergent studies, the National Institutes of Health only asserts “zinc lozenges might be useful as a treatment option.” It recommends more research and caution, particularly after the U.S. Food and Drug Administration warned consumers to stop using three Zicam intranasal cold-remedy products containing zinc when some users lost their sense of smell.

In contrast, studies show that good old chicken soup, which seems to have anti-inflammatory properties, might reduce the length and severity of colds. Drinking lots of fluids, gargling with salt water and breathing warm, humidified air that moistens your sinuses can help, too, by easing congestion.

• You’re less likely to get sick if you wash your hands and use hand sanitizers.

Yes, hand sanitizers can reduce your chances of getting sick by killing the viruses that cause the common cold. Washing hands frequently with soap and water for 30 seconds at a time is recommended.

• You should rush to the doctor at the first symptom for antibiotics.

No, antibiotics can only kill bacteria in a bacterial infection; a cold is a viral infection for which there is no cure. Doctors vary on how soon an otherwise healthy adult should go in for help. Some believe you can lessen the severity and duration of the cold by prompt, aggressive action, while others say you should wait it out unless you have severe vomiting, nausea or diarrhea or severe shortness of breath. Kids, the elderly and those with weakened immune systems are the most vulnerable and should be treated right away.

• The flu is just a big cold — wait it out.

No, the flu is a virus, as the cold is, but you should seek treatment right away as the flu has the potential to be life- threatening. Deaths in a three-decade period ranged from 3,000 to as high as 49,000 per season, while an average of 200,000 people a year are hospitalized, according to the Centers for Disease Control and Prevention.

You know you’re dealing with the flu, rather than a cold, if your temperature is 103 degrees or greater and you have a sudden onset of high fever, body aches and pains in six hours or less, which is not the case for colds.

Better yet, don’t wait to get the flu, say the experts at the CDC’s National Center for Immunization and Respiratory Diseases. If you haven’t been vaccinated yet, they advise getting immunized now — particularly children, senior citizens, pregnant women or those with chronic medical conditions such as asthma, diabetes and heart disease, as these factors put you at high risk for serious flu-related complications.