Cold Vs. Flu: How the Two Are the Same—And Different

The smell of peppermint mochas is in the air—and so are respiratory droplets, damn it. When your throat starts to hurt, your nose starts to run, and getting back into bed seems even more enticing than it usually does, you may have … something. But what? “It can be hard to tell a cold and flu apart,” says Kisha Davis, MD, a member of the board of directors of the American Academy of Family Physicians and the chief health officer for Montgomery County, Maryland. We enlisted her to help you figure out what ails you and what you can do about it.

What’s the difference between a cold and flu?

Both are respiratory illnesses, which means they affect the lungs and other organs that are responsible for breathing. But while flu is caused by influenza viruses only, a cold can be caused by more than 200 different viruses, according to Davis. These include rhinoviruses, enteroviruses, and (confusingly) coronaviruses, one of which causes Covid-19. “We call it the ‘common cold’ because people tend to get two, three, maybe four colds year, whereas the flu is something you usually get less than once a year,” says Davis.

How do I know if I have a cold or flu?

Common colds tend to come on gradually. Flu, on the other hand, is likelier to hit you suddenly—and hard. You might have a slightly elevated temperature with a cold, but it probably won’t hit fever territory (that’s 102 or higher). Common cold symptoms include nasal congestion, sore throat, and sneezing, and they tend to be milder than flu symptoms. With flu, “you might wake up in the morning with a full-on fever, nausea, chills, and muscle ache,” says Davis. (Coughing up phlegm? That’s a symptom of both a cold and the flu—and it’s not necessarily a sign of bacterial infection.) The good news: Flu may have more severe symptoms, but it usually lasts no more than a week, versus 10 to 14 days for a common cold.

Could my cold or flu symptoms actually be allergies? What about Covid?

Seasonal allergies can cause a runny nose and sneezing—but also itchy eyes and even ears, which are not common cold or flu symptoms. And while they tend to peak in spring, winter is prime cold and flu season. Because flu and Covid have similar symptoms, testing is the only way to know which one you have. In early 2024, the FDA approved over-the-counter 3-in-1 tests, also labeled Covid-19 and flu A/B tests, you can use to test for both illnesses at once.

Can I prevent cold and flu?

There’s a lot you can do to stay healthy. “Frequent handwashing, a healthy diet, and sleeping well—all of that really does make a difference,” says Davis. (Other proven ways to boost your immune system: Exercise regularly, try to keep your stress level low, and don’t smoke.) And remember how we said flu is caused by just a few types of viruses? Every year, health experts try to target the specific strains they think will be circulating that year—and when they do, flu vaccines have been shown to be 40 to 60 percent effective at lowering your risk of getting flu. (And if you do get the flu, a flu shot can reduce the severity of your illness and prevent hospitalization.) The optimal time to get a flu vaccine: The Centers for Disease Control and Prevention recommends that everyone 6 months of age and older get their flu shot by the end of October.

How do I treat cold and flu?

“The first thing is acknowledging that you’re sick, which means you need to rest more, hydrate more, and slow down a little bit,” says Davis. “Often we would get fitter faster if we said, ‘I’ll take that day or two to drink plenty of fluids and eat the chicken soup and not push through.’”

If you have the flu, antiviral drugs can shorten the duration of your illness by up to three days when taken within 48 hours of feeling sick. There are four FDA-approved antiviral drugs recommended by CDC to treat flu this season: oseltamivir phosphate (available as a generic or under the trade name Tamiflu), zanamivir (trade name, Relenza), peramivir (Rapivab), and baloxavir marboxil (Xofluza). (The CDC recommends that people who are at higher risk for flu complications, including pregnant women and young children, take it ASAP.) And acetaminophen and ibuprofen can alleviate body aches, including sore throat. “At the end of the day, though, most over-the-counter medications that help with symptoms are not going to help you feel better faster,” says Davis. (Some don’t even work temporarily: Last year, the FDA announced that a common ingredient in nasal decongestants, phenylephrine, is ineffective at clearing a stuffy nose when taken in pill form.) If you need to take something to push through a presentation, that’s fine, but what your body needs to heal are rest and fluids,” says Davis.

Regardless of which respiratory virus you have, “if you’re feeling sick, you should stay home,” advises Davis. When your symptoms have been improving and you haven’t had a fever for at least 24 hours, you’re typically less contagious, according to the CDC. But you can still spread the virus, so continue to take precautions—open windows and doors, mask when you’re in close contact with others, and keep washing those hands—for five days. After that, you’re typically much less contagious than you were when you first got sick.

When should I see my doctor?

If you develop a cough that doesn’t go away after two to three weeks, if your cough gets worse, or if you experience chest pain or difficulty breathing, make an appointment with your healthcare provider. These could all be symptoms of bronchitis, a condition that develops when the airways in your lungs become inflamed, or pneumonia, which causes your lungs to fill up with fluid or pus. (Both are potential cold and flu complications.) “Cold and flu viruses tend to affect your whole body, whereas bacterial infections tend to affect a part of your body,” says Davis. “So if the pain is localized, that suggests your viral infection has transitioned to an ear infection or a sinus infection that might benefit from antibiotics.”