How Long Am I Contagious When I Have the Flu?

Published July 2nd, 2022 by Chris Riley
Fact Checked by
Jacqueline Hensler
Medically Reviewed:
Dr. Angel Rivera

The flu is a viral infection that can leave you out of commission for several days and can stay contagious for even longer.

It is one of the most common illnesses every year with millions of people getting the flu but you may not be sure when you are no longer contagious if you had it.

In this article, we will answer all those questions and discuss what the flu is, its symptoms, and how it is spread.

We will also provide information on treatment options and ways to prevent the spread of the virus.

What is the flu?

The flu, also called influenza, is a respiratory illness caused by the influenza virus.

There are four different types of influenza viruses, although only three can affect humans.

The three types that affect humans are influenza type A, influenza type B, and influenza type C, and each type may also have specific strains of influenza.

Influenza type A is the most common and can cause severe illness, which makes it the source of all flu pandemics. Influenza type B usually causes a less severe illness but can still be dangerous.

Influenza type C is the least common and usually only causes mild illness.

The flu season is when the flu is most prevalent and, in the United States, it runs from October until May, normally peaking from December through February although it can vary from year to year.

The flu is different from the common cold in that flu symptoms are usually more severe than cold symptoms.

According to the Centers for Disease Control and Prevention (CDC), it is estimated that slightly over 8% of the population gets the flu every year in the United States although these numbers are an estimate and can vary depending on the year.

What are the symptoms of the flu?

The symptoms of the flu can vary from mild to severe and can last from several days to a couple of weeks.

There is a rapid onset of symptoms that come on suddenly and make you sick within a few hours.

The most common symptoms of the flu include:

  • Fever
  • Chills
  • Body aches and muscle pain
  • Dry cough
  • Runny nose or stuffy nose
  • Congestion
  • Sore throat
  • Headache
  • Fatigue or tiredness

You may also experience vomiting, nausea, and diarrhea although these symptoms are more common in children.

If you experience shortness of breath or difficulty breathing seek medical care immediately. 

What are the complications associated with the flu?

The flu can lead to severe complications, some of which may be life-threatening.

These complications include:

  • Respiratory infections such as bacterial pneumonia or bronchitis
  • Ear infections
  • Sinus infections
  • Making your asthma worse
  • Heart failure
  • Kidney failure
  • Brain inflammation (encephalopathy)
  • Heart inflammation (myocarditis)

Pregnant women may also experience complications such as premature labor and delivery.

There are certain medical conditions that can increase your risk for complications from the flu and these include:

  • Being over the age of 65
  • Being under the age of two
  • Neurological conditions
  • Chronic lung diseases such as asthma, chronic obstructive pulmonary disease (COPD), or cystic fibrosis
  • Blood disorders such as sickle cell disease
  • Diabetes mellitus
  • Kidney disease
  • Liver conditions
  • Obesity, particularly having a body mass index (BMI) of over 40
  • Having had a stroke
  • Metabolic disorders
  • Chronic health conditions that weaken the immune system such as HIV/AIDS, cancer, etc.

You may also be at a higher risk of getting the flu and developing complications if you are pregnant or postpartum for up to two weeks after you give birth.

If you are African American, Latino, Native American, or a Native Alaskan person you are also at a higher risk of developing the flu and its complications.

How is the flu spread?

The flu is spread through respiratory droplets when you are infected and cough, sneeze, talk, or sing.

It can also be passed on if you touch a surface that has the virus and then you touch your mouth, eyes, or nose.

You can also get the flu by having person-to-person contact with an infected person such as shaking hands or hugging them.

How long am I contagious with the flu?

After the flu enters your body, on average you will start to be contagious two days later although it can range anywhere from one to four days.

You are contagious one day before symptoms develop with the flu and normally stay contagious for up to five to seven days after your symptoms start.

If you have a weakened immune system or are elderly you may be contagious for longer and the same goes for children too.

The time when you are most contagious is the first three to four days and this is because you are most likely to cough or sneeze during this time period when your symptoms are the worst.

You are no longer contagious anymore when you do not have a fever for 24 hours without the aid of fever-reducing medication.

What are the treatment options for the flu?

If you are a healthy adult you will most likely not need to see your doctor and can recover at home.

To aid in your recovery, there are a few things you can do and these include:

  • Get lots of rest
  • Drink plenty of fluids to stay hydrated
  • Take over-the-counter medicine such as ibuprofen or acetaminophen for your fever

You may also want to take an over-the-counter cough suppressant if you develop a bad cough too.

See your doctor if you have severe symptoms or you develop a complication.

Your doctor may prescribe one of the four antiviral medications that are approved by the CDC to help combat the flu. These antiviral medications include:

  • Oseltamivir (Tamiflu)
  • Zanamivir (Relenza)
  • Peramivir (Rapivab)
  • Baloxavir marboxil (Xofluza)

Taking antiviral drugs can make your symptoms milder and shorter and also help prevent hospitalization.

It is important to note that these antiviral medicines work best when you start taking them within the first 48 hours of when your symptoms start.

Antibiotics will not help with the flu since it is a virus and they are only useful against bacterial infections.

What are the best ways to prevent the spread of the flu?

There are a few things you can do to help prevent the spread of the flu and these include:

  • Get vaccinated with a flu shot or flu vaccine nasal spray every year as this is by far the best way to prevent getting sick with the flu
  • Wash your hands often with soap and water or use an alcohol-based hand sanitizer when you are not able to wash your hands to stop the spread of germs
  • Avoid touching your eyes, nose, or mouth
  • Stay away from sick people and if you do get sick stay home from work or school until you have been fever-free for at least 24 hours without the aid of a fever-reducing medication
  • Cover your cough or sneeze with the crook of your elbow or tissue that you throw away
  • Clean and disinfect high-contact surfaces in your home or work that may be contaminated with the flu virus such as door handles, countertops, remote controls, tablets, phones, etc.

Eating a healthy diet and exercising regularly can also help prevent the flu by keeping your immune system strong.

If you get the annual flu vaccine you can still get the flu, however, your symptoms will likely be milder and last fewer days which also means you are not as likely to require going to the hospital for treatment.

Summary

The flu is a contagious virus that typically causes mild to severe respiratory illness.

It is most commonly spread through droplets when an infected person coughs or sneezes but can also be spread when you touch something contaminated with the flu virus and then touch your eyes, nose, or mouth.

You are most contagious with the flu during the first three to four days after your flu symptoms start but can usually still spread the virus up until a week after the start of your flu symptoms.

There are a few things you can do to help prevent the spread of the flu including getting vaccinated every year, washing your hands often, avoiding touching your face, staying away from sick people, and cleaning high-contact surfaces that may be contaminated with the flu virus.

If you have any more questions about the flu or about how long you may be contagious, please consult with your doctor or health care provider.

References, Studies, and sources:

WebMD

CDC