In Minnesota, we have road construction season (sometimes known as spring and summer) and cold and flu season (aka fall and winter). But how much do we really know about the common cold?

It's common, for one thing. Most adults get two to three colds a year. And while they're usually just a nuisance for most of us, they can be serious for the very young, the very old and people with compromised immune systems. They also cost the U.S. economy an estimated $40 billion a year, studies indicate.

We talked to Dr. Nipunie Rajapakse, an infectious-disease specialist with Mayo Clinic in Rochester, about the relationship between cold (weather) and a cold, if zinc can help, when to see a doctor and if there's a cold vaccine on the way.

Q: Let's start with the basics: What is a cold?

A: It's a viral infection that's usually acute (something that comes on relatively suddenly) and usually goes away on its own.

Q: Are colds caused by being in the cold?

A: It's a common misconception that if you go out in the cold, you'll catch a cold. We do see an increase in colds and flus in the fall and winter, but that's because people spend more time indoors — with other people.

Q: Are there other seasonal factors that contribute?

A: A decrease in humidity, which we see in fall and winter, can make us more susceptible to getting a cold.

Q: We're always looking for a quick cure for the common cold. Do over-the-counter drugs work?

A: They can offer symptomatic relief but don't affect the natural history of the cold. They won't prolong it or shorten it.

Q: What about zinc supplements?

A: There are some studies that have shown that people taking zinc see some slight indication of a shorter duration or severity, but it's not to the point where we would recommend it for the general population.

Q: Echinacea?

A: Talk to your doctor about side effects and interactions with other drugs.

Q: A neti pot?

A: If you have nasal symptoms, it's something people can use to make themselves feel better, but it probably won't make your cold better or worse.

Q: Chicken soup?

A: It has fluids and a bit of salt, so it may produce some symptomatic relief.

Q: So there's no quick fix, huh? Can you tell us what we shouldn't do when we have a cold?

A: Go to work or school sick. It's a bit of a hard sell that you need to do it [stay home] for other people. But what's just a cold to you could be dangerous for someone with a compromised immune system.

And don't take antibiotics. Antibiotics don't work for colds.

Q: How long does a cold typically last?

A: Most symptoms peak at one to three days, but a cold can last seven to 10 days.

Q: When should you think about going to see a doctor?

A: If you're sick more than 10 to 14 days. Colds also put you at risk for a secondary infection. So if you start to feel better and then get worse — fever, cough, shortness of breath — go in. Also, if you have unusual symptoms that have gone on for a long time, or if you've traveled.

Q: I thought a fever was a symptom of a flu, not a cold.

A: With a flu, we tend to see more fever and more systematic symptoms like chills, fatigue and body aches. But it can be impossible to tell the difference between a cold and a flu.

Q: There's a vaccine for the flu, why not the common cold?

A: Scientists, mostly in the United Kingdom, are working on a cold vaccine. But it's proven to be quite challenging. There are a few different viruses that cause colds, but many sub-strains or serotypes. There are more serotypes for the cold than the flu.

Q: We've been coughing and sneezing into our elbows, rather than our hands, for several years now. Has that slowed the spread of colds?

A: That's difficult to measure. But good cough etiquette and washing your hands is worth it. Hand washing is one of the best ways to prevent catching a cold.