Sept. 4, 2008 -- The sun may still be shining most of the day, the temperatures may still be above 70 degrees, and the pro football season hasn't kicked off yet. But around the country, some doctors are already receiving their shipments of flu vaccine.

With the start of flu season less than a month away, we took a look at 10 common bits of advice about colds and flu. Some of these common wisdom gems are, indeed, things you can and should do (it turns out that it's not too early for a flu shot -- and you might want to pick up some chicken soup). Others, however, are things you might want to pass on (the zinc and echinacea -- at least for now).

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While you may have heard some of these rumors since childhood, they aren't all things you really need to worry about. But some are useful to keep in mind.

Fact or Myth? If you get the flu vaccine too early in the year, your protection will wear off before flu season ends.

Answer: Myth

Some physicians already have their first flu vaccine shipments in, so people who believe this myth may be holding out when they don't need to.

The flu vaccine -- once understocked and reserved for the people most at risk -- is now readily available and recommended for everyone, so some doctors receive their shipments as early as August.

"I have now heard, this season, several times already, a concerned expressed that you can get vaccinated too early -- that you should wait until November because your protection may not last through February," when you are statistically most likely to get the flu, said Dr. William Schaffner, chairman of the department of preventive medicine at Vanderbilt Medical School.

But the vaccine lasts for at least a year, he said.

Schaffner said he has heard this expressed more among older patients. While he said that the flu vaccine may not respond or provoke as good a protection in those patients, it's not foreshortened.

"You can get vaccinated right now, and your protection will persist," he said.

Fact or Myth? You can catch the flu from a flu shot.

Answer: Myth

"That's the biggest myth, that's really huge. And it inhibits many people from thinking about getting their influenza injection," said Schaffner.

The idea rises from the popular misconception that the flu vaccine shot is a weakened form of the flu virus. The flu vaccine contains components of the flu virus but not a complete virus.

"There's no way that the shot can give you a complete influenza virus that can then make you ill," Schaffner said.

The reason many might believe that the vaccine can cause the flu, said Schaffner, is that people tend to get the flu vaccine in October or November, and then catch a cold from someone else.

Since the viruses that cause cold are contagious 24 hours before the symptoms appear, someone who had a flu shot and then caught a cold might believe he or she has the flu and can't think of another source because the person whom they got it from didn't appear sick.

Of course, in recent years, another form of the flu vaccine -- a nasal spray known as FluMist -- has also become popular.

The nasal spray, Schaffner explains, is a "tamed virus." In this case, it has been engineered to multiply in the nose, but it can't get down into the rest of the body because the rest of the body is a degree or two warmer than the nose, and the virus is incapable of multiplying at that higher temperature.

"It's a miracle of modern science," he said.

However, the nasal spray form of the flu vaccine may leave someone symptomatic for a day with a runny nose and a sore throat.

"That's a small price to pay, in my opinion," said Schaffner.

Fact or Myth? Stress increases your chances of getting a cold or the flu.

Answer: Undetermined

"This is a very good question and a question we don't know all the answers to," said Dr. Erica Brownfield, an associate professor of medicine at Emory University School of Medicine.

But while medicine may not be able to tell us if stress increases the risk of catching a cold or the flu, stress can make either of those conditions worse once you have it.

"What we do know is that those people who are under chronic stress are probably more likely to develop complications from a cold or the flu," said Brownfield.

While people may need to relax once they're sick, the anxiety of putting yourself at higher risk isn't worth adding to an already stressful lifestyle.

"For those individuals who have acute stress in their life, they shouldn't be concerned about developing more colds and flu under typical circumstances," said Brownfield.

Fact or Myth? Lingering in wet clothes, going outside in cold weather with wet hair or just being cold can increase your chances of getting a cold.

Answer: Myth

"No, being out in the cold or being cold or having wet clothes does not increase your chance of having a cold or the flu," said Dr. Jon Abramson, chairman of the department of pediatrics at Wake Forest University Baptist Medical Center.

"This is one of the myths that do exist both about the common cold or the flu, and clearly from a lot of studies this is not the case."

Since this myth persists, the likely reason behind it is the rise in cases once the temperature drops in the United States.

"It is true, however, [that] the flu virus circulates mainly in the fall and the wintertime, and that therefore, you do see a lot more flu during that time than the rest of the year in temperate countries, such as the United States," said Abramson.

While the viruses are more common during these times of the year, the consensus among physicians seems to be that this is caused by people staying indoors to avoid the cold -- not from the cold itself.

Fact or Myth? Flying on an airplane will increase your risk of catching a cold or the flu.

Answer: Fact

Riding on an airplane may increase your flu risk, but it's not clear if it makes it any higher than do other crowded areas.

"I think anytime that you are in a crowd of people, the risk that you might catch a cold or catch the flu is increased. We tend to catch these illnesses from other people. And so when you're in a crowd, the likelihood that you'll come in contact with somebody who's infected naturally goes up," said Dr. Ronald Turner, a pediatrician at the University of Virginia School of Medicine.

Flu risk may be particularly elevated in these situations, because it is spread by germs in the air.

"Influenza ... is spread by aerosols, which is when the virus gets into the air. And so, when you're in a crowd with somebody who has influenza, your risk of catching influenza does go up," Turner said.

Your greatest cold risk may not be from strangers in a crowd but from little ones close to you.

"The types of interactions that are associated with colds are more typically the types of interactions that we have with children, where the interaction is more direct and maybe less guarded. And those situations are the situations in which you're most likely to catch a cold," said Turner.

Fact or Myth? Echinacea or zinc can help prevent or shorten the length of a cold.

Answer: Probably a Myth

Both zinc and echinacea have had a number of studies done on them, and neither has been shown conclusively to help battle colds.

"There have been a number of studies of echinacea. Some have purported to show some modest benefit. However, I think the weight of the evidence is that echinacea has no benefit, either on incidence of illness or severity of illness," said Turner.

He said the results for zinc have been similarly ambiguous.

"There are a number of studies that have been done looking at the effect of zinc, primarily on the severity of illness and duration of illness," said Turner. "Those studies have been split really between studies that show fairly dramatic effects and then an equal number of studies at least that show very little or no effect."

While the evidence is not entirely conclusive, Turner said, he wouldn't be rushing out to get his hands on some zinc.

"I think it's a little hard to know exactly what the final answer is on zinc right now, although, in my opinion, I suspect that it doesn't have a whole lot of impact on common cold illness," he said.

Fact or Myth? Putting on extra clothing or covering yourself in blankets can help you "sweat out" a cold.

Answer: Myth

Frustration with an illness we can't cure may lead to these attempts, explained Dr. Lisa Bernstein, an assistant professor of medicine at Emory University.

"Unfortunately we haven't gotten smart enough in modern medicine to cure the common cold, so a lot of people are looking for their own way to do so. One of those is to possibly cover yourself with blankets and try to sweat out a cold."

But trying to sweat out a cold won't accomplish much, she said.

"Unfortunately, that's not going to do it. The cold is caused by over 200 viruses, and it just takes its time up to several days to several weeks for your cold to get out of your system."

However, feeling better may be just as important as getting better, Bernstein said, especially with an illness that takes time to get over.

"Do whatever makes you feel better -- whether it's putting more blankets on if you feel a chill, drinking warm liquids, or taking over-the-counter medication. It's just going to take time," she said.

Fact or Myth? "Feed a cold, starve a fever." Or "Starve a cold, feed a fever."

Answer: Myth

Regardless of which version you've heard, you won't be hearing either from your doctor.

"That's a very common old wives tale to say feed a cold and starve a fever. Unfortunately you really shouldn't do the extreme of either when you're treating a cold or the flu," said Bernstein.

Forcing yourself to eat won't accomplish much, she said.

"Oftentimes when we get a cold or the flu, we lose our appetites, and that's very, very common. It's not important to force feed yourself in order to keep up with the cold."

Instead, you should focus on drinking enough.

"It's very important to stay hydrated when you have upper respiratory infection or a cold, and especially the flu, as well, because when you sweat a lot you're going to lose a lot of moisture," said Bernstein.

"If you can eat that's wonderful because good nutrition will definitely help you get better faster as well. But at least stay hydrated."

Eating can help, but not when it's forced.

"It's important to drink lots of fluids and try to eat as much as possible and keep good nutrition when you are ill. However, it's absolutely not important to starve yourself or to overeat in order to treat either of these conditions," said Bernstein.

Fact or Myth? Chicken soup, hot liquids or honey can help you feel better sooner if you have a cold.

Answer: Fact

"You might have heard from your mother or your grandmother in the past that chicken soup is the cure for the common cold," said Bernstein.

While this tip goes at least as far back as the 12th century physician Maimonides (who some historians believe heard it from his mother), there is now solid medical evidence behind a remedy that was once only thought of as merely a comfort food.

"Even Maimonides, years and years ago, said that chicken soup is a great medication as well as food. But things like chicken soup, up until recently, were thought to only help by being a warm liquid that would soothe the nasal passages, keep the mucus flowing a little bit better and just make you feel better by eating something warm," said Bernstein.

In 2000, University of Nebraska researchers showed this old remedy had wider benefits.

"There was a study ... that showed that it does actually have an anti-inflammatory effect, mobilizing the neutrophils or the inflammatory cells and making them work a little bit better -- and also keeping the mucus in the nose moving so that the virus, which sits in the nose, would mobilize a little bit faster and, maybe, potentially, get you better faster," explained Bernstein.

The evidence isn't quite as clear on other home food remedies, however.

"Things like warm tea or honey or other foods, however, have not been shown medically to help. Although they might make you feel better just from their warmth and their soothing effect," said Bernstein.

"So it's important to just keep your nutrition up, keep hydrated, and if you like chicken soup, go right ahead."

Fact or Myth? There is no way to reduce the duration of a cold or the flu.

Answer: Myth

While the mythical status of most of these remedies may suggest that there's no way out of a layover with cold or the flu, there appears to be one way to cut down sick days from the latter if you are quick about it.

"You can, if you catch genuine influenza early enough, actually take an antiviral that can shorten the duration of the illness," said Schaffner.

But the key to cutting the flu short this way is to act immediately.

"You have to get in to see the doctor within the first 48 hours," he said.

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