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How to Tell If You Have the Flu or Just a Cold

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So the sniffles have set in. At least you’re in good company: There are always plenty of runny noses to go around this time of year — and hey, you may have already heard about this, but we’re in the middle of an especially bad flu season, too. Even getting a flu shot is no guarantee you won’t end up with the flu that everyone seems to be getting this year, and it definitely doesn’t protect against the common cold.

But how do you know which one you’re dealing with? It can be tough to tell the difference between your run-of-the-mill cold and the flu.
Both bring on lethargy, headaches, and runny noses. Both are caused by viruses. Both can be picked up from spending time around sick people who are sneezing and coughing, or by touching infected surfaces. If you’re feeling crummy but aren’t sure of the culprit, here’s how to figure it out.

What kind of symptoms do you have?
The flu usually comes with a fever, and that’s rare with a cold, says infectious disease expert Casandra Hoffman, a postdoctoral research associate at the University of Virginia. “You may get some achiness with the cold, but the flu makes you feel like you’ve been hit by a bus,” she says. “Chills are common with the flu, but uncommon with a cold.” And while both illnesses can feature a runny nose, the cold is much more likely to cause the feeling of being completely stuffed up.

What was the onset of symptoms like?
One of the biggest distinctions between a cold and the flu is how quickly the symptoms start. You may feel like you’re getting a cold for a few days, but the flu tends to sneak up on you.

“The cold progresses a little slower,” Hoffman says. “So you may start to feel a little sick, the next day it’s a little worse, and by the third day you’re really, full-blown sick. When it’s the flu, you’re fine one day and very sick the next.”

When is it time to see a doctor?
For the most part, you can ride out either illness by self-medicating with rest, over-the-counter meds, and — it’s worth saying again — not going to work. But the flu does pose a threat to at-risk populations like children and people over 65.

“Most of the time, the flu is a mild illness and you don’t really need an antiviral,” Hoffman says. “But there are some emergency warning signs that require medical attention.”

In children, she says, parents should watch for difficulty or reluctance to wake up from a nap. Sick kids should also be taking in a lot of fluids, and if a child starts refusing to drink, there’s a real problem.

“If kids are very irritable and don’t want to be held, that’s cause for concern,” Hoffman continues. “Most kids want to be held when they’re sick. If a high fever — between 100 and 103 degrees or even higher — persists over several days, that child needs to be seen by a doctor.”

Flu sufferers over 65 need emergency medical attention if they experience shortness of breath, severe or persistent vomiting, pressure in the chest, serious confusion or dizziness.

Hoffman also says healthy adults getting over the flu should pay close attention to recurring symptoms. “If you’re sick with the flu, then feel better for a day, then your symptoms return way worse, that’s indicative of pneumonia,” she says. “It’s a secondary infection, and it warrants getting to a doctor.”

If you’re uncertain about whether it’s a cold or the flu that’s plaguing you, the most important thing you can do is just stay home. A recent study at the University of Maryland School of Public Health found that people with the flu produce aerosols — tiny droplets that remain in the air for an extended period of time — full of the infectious virus. That means you can give the flu to someone else just by breathing near them, so no matter how much of a workaholic you are, if there’s even a small chance you’ve got the flu, please stay home.

How to Tell If You Have the Flu or Just a Cold