Cold vs. Flu: How To Tell the Difference

Runny nose, headache, sore throat — when you’re feeling miserable, the last thing you want to do is play detective. But puzzling out whether you have a cold or the flu can help you know what to expect and when to get help.

So, how can you tell the difference? And what should you do if you’re not getting better?

We asked family medicine physician Neha Vyas, MD, to walk us through the differences between a cold and the flu. And what you should look for and when you should seek treatment.

What causes colds and flu?

Both the common cold and the flu are viral infections. But different viruses cause them.

The influenza virus causes the flu. On the other hand, a long list of suspects causes colds.

“There are hundreds of viruses that can cause a cold,” Dr. Vyas says. “Most commonly, they’re caused by rhinoviruses, but also parainfluenza viruses, and even some seasonal coronaviruses (not to be confused with COVID-19).”

And each of those viruses can mutate, leading to countless strains of viruses that can get you down with the sniffles and all the other yuck that comes with a cold.

Cold vs. flu: Comparing the symptoms

Colds and the flu can have some overlapping symptoms. (A lot of them, in fact.) But there are a few telltale signs that can help you decide what you might be dealing with.

Symptoms can be a good guide for trying to sort out what has you down. But if you’re not sure, a flu test (either at home or in a provider’s office) can tell you if it’s the flu.

How long does the flu last compared to a cold?

Colds are usually shorter-lived than the flu.

“People feel worse longer with the flu,” Dr. Vyas confirms.

A common cold takes a few days to ramp up. Symptoms tend to peak around day five and typically resolve within a week to 10 days.

The flu is more of a direct hit.

“The flu comes on without much warning,” Dr. Vyas continues. “One day, you’re fine, and the next day, you feel like you’ve been hit by a truck. With a cold, you may question whether you’re getting sick for a couple of days because it comes on gradually.”

The flu typically sticks around for seven to 10 days, but it can last for several weeks.

Some cold and flu symptoms, like a cough, can linger long after other symptoms have cleared up.

Which is stronger: cold or flu?

Short answer: The flu is stronger. Hundreds of thousands of people in the United States are hospitalized from the flu each year.

“Flu symptoms are more intense, and they can lead to more serious complications,” Dr. Vyas reports. “Colds are usually self-limiting — most people get better with over-the-counter medications and home remedies without much of an issue.”

A cold that doesn’t completely clear up can lead to issues like sinus infections, ear infections or bronchitis. Those are typically well-managed with medications.

But the flu can have more severe complications.

“The flu can lead to hospitalization, pneumonia and, in extreme cases, death,” Dr. Vyas warns. “That’s why we take it so seriously.”

The flu can just be a blip on the radar for some people. But you can be at risk for dangerous flu complications if you:

• Are under the age of 5
• Are over the age of 65
• Are pregnant
• Have heart, lung or kidney disease, diabetes or a blood disorder
• Live with immunocompromise

When to worry

Most colds don’t require a trip to the doctor. And for people who are otherwise in good health, the flu may not either.

But if your symptoms linger or get worse, it’s time to pay attention.

“If by day six or seven, you’re feeling worse instead of better, that’s a red flag,” Dr. Vyas says. “And if you start to feel better, then get worse again — we call that a bimodal presentation — it can signal a secondary infection.”

Other signs that you should call your provider:

• A fever that won’t go away
• Chest pain or shortness of breath
• Severe headache
• Dizziness or confusion
• Trouble staying hydrated

If you’re at high risk for flu complications, your provider may recommend an antiviral medication to help ease your symptoms and shorten the duration of the flu. But timing matters.

“You have to take them early for antivirals to work,” Dr. Vyas explains.

Antiviral medication doesn’t work for cold viruses.

Preventing colds and flu

You can’t avoid every germ, but you can lower your risk of getting sick — or spreading cold and the flu to others.

Dr. Vyas offers these prevention tips:

• Wash your hands frequently, especially after using the bathroom and before you eat.
• Stay home when you’re sick (and keep your kids home when they’re sick, too).
• Consider getting a flu shot, particularly if you’re at higher risk for flu complications or spend time with people who are.
• Consider wearing a mask in crowds during cold and flu season.

Bottom line

Colds and the flu may look similar sometimes, but the effects of the flu can be more dangerous. So, knowing which bug is bugging you can make a difference.

“When in doubt, talk to your doctor,” Dr. Vyas advises. “It’s always better to be safe, especially when early treatment can make a difference.”

And no matter what you’re dealing with, she adds, “Stay home, rest, hydrate and take care of yourself. That’s how we get through cold and flu season together.”