How Long Does the Flu Last?

By Sarah Malka, MD
Medically reviewed
November 8, 2021

When symptoms like a sore throat and stuffy nose set in, you often wonder two things: What is this, and how long will it last?

You could be dealing with allergies, a cold, or the flu, and each has a different timeline.

In the case of the flu, unfortunately, you may be downright miserable for a few days.

To help you prepare, in this article, we’ll break down the lifecycle of the flu, including how long you may experience symptoms, when you are contagious, and how long you should avoid interacting with others.

We’ll also advise when you should consider seeing a doctor. This way, you’ll be armed and ready for flu season. 

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Influenza (Flu) Basics

The flu (the illness caused by influenza viruses) is a respiratory virus that’s transmitted from person to person when an infected person speaks, coughs, or sneezes, sending tiny droplets containing the virus into the air.

The flu can also spread through kissing, sharing utensils, or touching contaminated surfaces and then touching your mouth, nose, or eyes. 

Symptoms of the flu typically come on quickly.

The most common symptoms are:

Influenza viruses are active year-round, but you are most vulnerable during flu season, when cases rise.

This season typically begins in the fall (generally October) and ends in the spring (generally April or May). 

Because there’s no cure or effective treatment for the flu, prevention is important.

Practice proper hygiene, get the flu vaccine, wear masks, and avoid others who are ill. 

How Long the Flu Lasts

For healthy individuals, the flu is typically a fairly short-term illness, lasting no longer than a week or two.

Luckily, you won’t feel miserable the entire time.

Below is a timeline of a bout of the flu.

Incubation period

The time from when you’re exposed to a virus until symptoms first begin is called the incubation period.

For the flu, this takes 1-4 days, with an average of two days.

This means you may be contagious a day or two before symptoms start and can unknowingly spread the virus during that time.

Symptoms appear

Symptoms like cough, sore throat, fever, and runny nose generally show up 1-4 days after being exposed to the influenza virus.

Not everyone has the same symptoms, and certain symptoms, like vomiting and diarrhea, are more common in children or with certain strains of the flu.

If your symptoms are severe or you are immunocompromised, consider talking to a doctor or healthcare provider at this time. 

Symptoms peak

Flu symptoms generally peak 2-4 days after they begin, then begin to gradually improve on their own.

You are also most contagious 3-4 days after symptoms start. 

Symptoms taper off

For otherwise healthy individuals, flu symptoms typically begin tapering off five days after they start.

However, coughing and a general “sick” feeling may last for more than two weeks, especially for the elderly and those with chronic lung disease. 

Recovery

With rest, over-the-counter (OTC) medications, and plenty of fluids, you’ll be on the road to recovery in no time.

However, even as you begin to feel better, it’s important to stay away from others for a little while to ensure you don’t spread the flu.

You are contagious from 5-7 days after symptoms emerge, so it’s best to stay home for a week after you first begin feeling sick.

If fever is one of your symptoms, stay home for at least 24 hours after your fever is gone. 

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When to See a Doctor

With proper self-care, the flu typically goes away on its own, especially if you are otherwise healthy.

However, certain high-risk people should seek medical care when they come down with the flu to help watch for and prevent any serious complications such as pneumonia.

This includes: 

  • Adults 65 and older
  • Anyone with chronic illnesses (especially those that affect the lungs or immune system)
  • Pregnant people
  • Very young children with severe symptoms

Antiviral medications can help make flu symptoms go away about one day faster.

However, these need to be started within 72 hours of symptoms appearing, they can have bothersome side effects, and they do not prevent serious complications like hospitalization, pneumonia, or death.

Your healthcare provider can help you determine if these medications are right for you.

How K Health Can Help

Did you know you can get affordable primary care with the K Health app?

Download K Health to check your symptoms, explore conditions and treatments, and if needed text with a doctor or licensed advanced practice practitioner in minutes.

K Health’s AI-powered app is HIPAA compliant and based on 20 years of clinical data.

Frequently Asked Questions

What is the fastest way to recover from the flu?
The best thing you can do to recover from the flu as fast as possible is to stay hydrated, rest, and isolate. There is no cure for the flu, antibiotics are ineffective against it, and antiviral medications like oseltamivir (Tamiflu) only make symptoms go away about one day more quickly and can have side effects. Over-the-counter medications may provide some relief from symptoms, but they do not make the flu go away any faster.
How long does immunity to the flu last after getting sick?
Because there are so many different strains, it’s hard to say how long immunity to the flu lasts after getting sick. On the other hand, if you get the flu shot, you’re protected against multiple variations of the virus for about six months.
How long should you stay at home with the flu?
Because the flu easily spreads from person to person, it’s important to stay home when you may be contagious. Generally, this is from a day before and up to seven days after symptoms start. So stay home for a week after you first feel sick to help keep others safe.
K Health articles are all written and reviewed by MDs, PhDs, NPs, or PharmDs and are for informational purposes only. This information does not constitute and should not be relied on for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.

Sarah Malka, MD

Dr. Sarah Malka is a board certified emergency medicine physician with K Health. She completed her residency at Harvard Medical School.