Flu Types and Symptoms

The flu – or influenza – is a contagious respiratory illness, which attacks the body by spreading through the respiratory tract. It is typically spread through the air or direct contact from one person to another.[1] Most experts believe that it is most often passed by the tiny droplets made when those with the flu talk, cough or sneeze.[2]

The flu can vary in its severity, from relatively harmless to extremely harmful – and tends to be more prominent in fall and winter.[3] Symptoms can range from sore throats and nasal congestion to fatigue, high fevers and vomiting, which we will offer further detail on throughout. In this piece, we’ll take you through the different types of flus, as well as the signs and symptoms you should look out for.

How many types of flu are there?

There are three main types of flu viruses that affect humans (A, B and C).[4]

The different types of flu

What is type A flu?

Type A is typically thought to be more serious than Type B – and is known to cause serious outbreaks that can increase your risk of disease. It is characterized by subtypes and strains and they are always constantly changing from one season to the next. These types are naturally hosted by wild birds such as ducks, geese, shorebirds and some mammals and an example of this is swine flu.[5]

What is type B flu?

Type B influenza is only found in humans – and people tend to see it as less severe than type A. This has been challenged in recent years however, and The Centers for Disease Control and Prevention reported that this could be equally as dangerous.[6]

What is type C flu?

Type C is the mildest form of the flu. For most people, this usually only causes mild respiratory infections.[7]

What type of flu is the worst?

At one time, Type A was considered more serious than Type B. However, studies have found that both Influenza A and B could result in similar rates of illness and/or death.[8] Type C is the mildest form of flu and usually shows similar symptoms to that of the common cold in adults.[9]

Do I have the flu?

If you’re wondering whether you have the flu, it can help to look at how this differs to the common cold:

Do I have a cold or the flu?

Many symptoms of the common cold are similar to that of the flu, and many people that have a heavy cold can think they have the flu. However, a common cold usually includes the likes of sneezing, stuffy nose and a sore throat, whereas the flu often consists of fevers, aches and chills too.[10] Although they are both viral infections of the respiratory tract and are contagious, the cold is far less severe than the flu – and the flu can have more serious complications that result in bacterial infections or hospitalizations.[11] Below are some of the symptoms associated with the flu:

What are the symptoms of the flu?

  • A high fever
  • Chills or sweats
  • Sore and aching muscles
  • A headache
  • Nasal congestion
  • Sore throat or a dry cough
  • Fatigue and weakness
  • Loss of appetite

Many people with the flu that have mild illness do not need medical care or drugs. If, however, you are very sick and are growing worried, you should contact a health care provider immediately.[12]

Common FAQs

How long do flu symptoms last?

According to Harvard Medical School, the answer depends on your own health. There are also some people that are at risk of more severe reactions – such as those who are very young, older than 65, or people who are pregnant or with chronic illnesses etc. However, they suggest that symptoms usually appear from one to four days after exposure, and last from five to seven days.[13]

Is diarrhea a symptom of the flu?

Diarrhea, stomach pains, nausea and sickness can be the flu, but this is not something that happens often. If this is the case, you may actually have “stomach flu”. Despite its name, this is not actually flu – or influenza – and is when your stomach and intestines are inflamed and irritated.

Please note: Always use Lysol® products as directed on the label.

Always keep your surfaces disinfected with Lysol® Disinfectant Spray or Wipes to decrease the amount of flu germs in your area. And, if you’re feeling very sick or your symptoms don’t improve, be sure to seek medical attention.


[1] https://www.health.harvard.edu/a_to_z/flu-influenza-a-to-z

[2] https://www.cdc.gov/flu/about/keyfacts.htm

[3] https://www.cdc.gov/flu/about/season/flu-season.htm

[4] https://www.cdc.gov/flu/about/viruses/types.htm

[5] https://www.healthline.com/health/influenza-a-symptoms#influenza-a-vs.-influenza-b

[6] https://www.healthline.com/health/influenza-a-symptoms#influenza-a-vs.-influenza-b

[7] https://www.healthline.com/health/influenza-a-symptoms#influenza-a-vs.-influenza-b

[8] https://www.healthline.com/health/cold-flu/influenza-a-vs-b#vaccine-effectiveness

[9] https://www.healthline.com/health/cold-flu/influenza-a-vs-b#vaccine-effectiveness

[10] https://www.cdc.gov/flu/symptoms/coldflu.htm

[11] https://www.cdc.gov/flu/symptoms/coldflu.htm

[12] https://www.cdc.gov/flu/treatment/takingcare.htm

[13] https://www.health.harvard.edu/staying-healthy/how-long-does-the-flu-last