How do you know if you have the flu?


MNT Knowledge Center

There are some clear ways to determine whether you are suffering from the flu or just a bad cold.

Both the flu and a cold are respiratory infections caused by viruses and the symptoms of these infections often overlap. This can sometimes make it difficult to determine whether someone is suffering from the flu or a bad cold.

According to a study published in The Lancet1, “the common cold and influenza (flu) are the most common syndromes of infection in human beings.”

Despite the flu and the common cold having similar symptoms, symptoms of the flu are usually a lot more severe.

This Medical News Today information article provides details on the symptoms of a flu virus infection, what to do if you have the flu, emergency warning signs indicating when you should seek medical attention, and how to protect yourself from the flu.

Signs and symptoms of the flu

Flu Facts estimates2 that between 5 and 20 percent of the U.S. population suffer from the flu every year. More than 200,000 people are hospitalized because of flu complications, and the flu is responsible for around 23,600 deaths every year.

There are three types of flu viruses that exist – influenza A, influenza B and influenza C. Types A and B viruses are the ones that cause seasonal epidemics.

According to the U.S. Department of Health & Human Services3, symptoms of the flu include:

Symptoms of flu

  • Feeling feverish or having a 100oF or higher fever or feeling feverish. However, it should be noted that not everyone with the flu will have a fever.
  • Headaches or body aches
  • Vomiting, nausea, and/or diarrhea (particularly among children)
  • Sore throat
  • Cough
  • Fatigue
  • Chills
  • A congested or runny nose

People suffering from a common cold are less likely to have a high fever. In addition, symptoms such as a runny nose or throat irritation typically improve within a few days.

However, the flu virus can cause a high fever that can last 3 to 4 days, while other symptoms such as extreme fatigue can persist for weeks.

Video – What are the symptoms of the flu? – U.S. Department of Health and Human Services (HHS)

What to do if you have the flu

According to the U.S. Centers for Disease Control and Prevention4, the majority of people who suffer from the flu do not need to seek medical attention. Most can remain at home and just avoid contact with other people to prevent it from spreading.

However, some population groups may be at a greater risk of severe flu-related complications.

Those at a high risk of severe flu-related complications include patients with certain medical conditions, young children, seniors, and pregnant women.

If you belong to a high risk group you (or a friend/family member) should contact your doctor and inform them that you are currently suffering from the flu.

Flu warning signs

The CDC4 says that medical help should be sought if you notice any of the following warning signs.


  • difficulty breathing
  • bluish skin color
  • not drinking enough fluids
  • not waking up or not interacting
  • being so irritable that the child does not want to be held
  • flu-like symptoms improve but then return with fever and worse cough
  • fever with a rash


  • trouble breathing
  • no appetite
  • no tears when they cry


  • difficulty breathing
  • pain in the abdomen
  • confusion
  • persistent vomiting
  • dizziness

The flu shot and how to protect yourself from the virus

Canada’s Ontario Ministry of Health and Long Term Care5 says that the best way to protect yourself from the flu is by getting the flu shot as it helps the body build the necessary defenses to quickly fight off the virus.

In addition to taking the flu shot you can also minimize your risk of catching the flu by frequently washing your hands with soap and water, avoiding large crowds, keeping at least a 60% alcohol hand sanitizer nearby, and avoiding frequently touching your face.

Recent developments on flu prevention from MNT news

Universal flu vaccine closer after natural immunity study. A group of UK researchers at Imperial College London say they are a lot closer to developing a universal flu vaccine that would protect against all strains of seasonal flu and curb future pandemics. Their finding was reported in the journal Nature Medicine.6