There are four types of influenza virus: influenza A, B, C, and D. Types A and B are responsible for the flu epidemics that occur in the United States most winters. Influenza B usually causes a milder form of flu than influenza A.

Influenza, or the flu, is a respiratory illness that is very common during the winter months. It affects the lungs, nose, and throat, causing symptoms such as a cough, body aches, and a sore throat. These symptoms may be mild, but they can be severe.

The illness results from a virus that spreads very easily from person to person.

Someone can contract the virus by coming into close contact with a person who has the infection or by touching a surface that the person has touched, then touching their own mouth or nose.

Type C influenza tends to cause a mild respiratory illness and does not usually result in epidemics. Type D influenza mainly affects cattle, not humans.

In this article, we take a look at the symptoms of influenza B, along with how people can treat and, possibly, prevent it.

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Flu symptoms tend to come on suddenly. They may include one or all of the following:

In some cases, people feel very hot or feverish.

A person with the flu may also experience vomiting and diarrhea. These symptoms are more common in children than in adults with the flu.

The common cold can have similar symptoms to the flu. However, cold symptoms typically come on more slowly.

How does influenza B differ from types A and C?

Influenza B tends to cause a milder form of the flu than influenza A.

While influenza A can lead to moderate-to-severe flu symptoms across all age groups, and in animals, influenza B only affects humans.

Also, influenza B typically affects children more often than adults. It generally causes stronger symptoms than influenza C.

Flu resources

For more information and resources to help keep you and your loved ones healthy this flu season, visit our dedicated hub.

In many people, the flu goes away on its own without treatment. However, older adults and people with certain underlying health conditions may have a risk of developing serious complications.

Such complications include:

Any of these may require a person to need treatment in a hospital. In extreme cases, they can lead to death.

Having the flu can also worsen the symptoms of other health conditions, such as asthma or chronic obstructive pulmonary disease, better known as COPD.

If a child or adult experiences any of the following flu symptoms, they should receive medical care immediately:

Also, if a child is not alert or interacting while awake, or if their ribs pull inward while breathing, seek urgent care.

In most people, the flu goes away on its own within 2 weeks. While they are recovering, a person with the flu should:

  • stay at home
  • avoid contact with other people
  • drink plenty of water

Several over-the-counter medications can help ease the symptoms of influenza. These are available from drug stores.

In severe cases, a doctor may prescribe a course of antiviral drugs. Oseltamivir (Tamiflu) and zanamivir (Relenza) are drugs that doctors may use to treat type A or type B influenza.

Antiviral drugs can reduce a person’s recovery time by around 2 days, but they are only effective if a person takes them within a few days of symptoms starting. Antiviral medicines are available as pills, a liquid, or an inhaled powder.

Anyone with the flu who experiences any of the following symptoms should speak to a doctor as soon as they can:

  • a cough that produces green or yellow mucus
  • breathlessness, even while resting
  • feeling dizzy or faint
  • an uncontrollable shuddering or shaking
  • a fever of more than 101°F

Seek urgent medical care if a newborn has any fever.

The Centers for Disease Control and Prevention (CDC) recommend that anyone aged 6 months or older receive an influenza vaccine every year, with few exceptions.

The CDC emphasize that it is especially important for people who have a risk of developing flu complications to get the vaccine.

People who have an increased risk of flu complications include:

  • adults aged 65 and older
  • pregnant women
  • young children
  • people with diabetes
  • people with heart disease
  • people with cancer
  • children with neurological conditions, such as brain disorders

Because influenza spreads so easily, people who work with those in high risk groups should be careful. Experts advise that all people who work in healthcare receive flu vaccination.

Most available vaccines are quadrivalent, meaning that they protect people from four types of influenza: two types of influenza A and two types of influenza B.

Babies younger than 6 months and anyone with an allergy to a vaccine ingredient should not get the flu shot.

People with any allergies and people with a condition called Guillain-Barré syndrome should consult a doctor before having the vaccine, as they may be unable to receive it.

Maintaining good hygiene can help stop the spread of flu. This includes always covering the mouth when coughing or sneezing.

It is also a good idea to ensure that the hands are clean before touching the face. This is especially important when the viral infection is most common, during the winter months.

The illness caused by the influenza B virus tends to go away by itself within a week or two. Anyone who is experiencing flu symptoms should stay at home and drink plenty of fluids.

For some people, the flu can be dangerous. Older people, young children, and people with some underlying health conditions can develop life threatening complications if they catch the flu.

The CDC recommend that anyone in a high risk group speak to their doctor about vaccination. The same is true for people who come into regular contact with those in high risk groups, such as healthcare workers.

Anyone in a high risk group who does catch flu should speak to a doctor right away.