How long is someone with the flu contagious?

With flu season making it's earliest start in years, and certain strains of the virus hitting unlucky Americans hard this year, it’s important to be extra vigilant in your efforts to avoid catching it.

I recently got this question emailed to me by a concerned viewer:

Q: When is someone who has the flu contagious?

Some people who are infected with the influenza virus can actually transmit the illness before they begin to feel any symptoms.

Most of the time, you will become contagious about 24 to 72 hours after contracting the influenza virus and remain that way for up to five days after the onset of symptoms.

But children or people with compromised immune systems can be contagious to those around them for up to two weeks.

Flu is most commonly spread by coming into contact with respiratory moisture droplets from an infected person through sneezing or coughing.

Touching a surface tainted with respiratory droplets – and then putting your hands up to your nose or mouth – can also infect you.

Flu symptoms include:

  • Fever
  • Chills
  • Runny nose
  • Headache
  • Muscle aches
  • Warm, flushed skin and watery eyes
  • Weakness or fatigue
  • Sore throat

The symptoms of the common cold can be similar to those of the flu, so it's important to get a firm diagnosis from your doctor.

According to the CDC, more than 20,000 Americans die from the flu each year, so make sure you get your flu shot – especially if you are pregnant or living with a compromised immune system.