A high fever, coughing, body aches, chills, and fatigue are possible symptoms of influenza B. They may indicate other conditions. Only a healthcare professional can provide an accurate diagnosis.

Influenza — commonly known as the flu — is a respiratory infection caused by flu viruses. There are three main types of influenza: A, B, and C. Types A and B are similar, but influenza B can only pass from human to human.

The Centers for Disease Control and Prevention reports both types A and B can be equally severe, challenging a previous misconception that type B tends to be a milder disease.

A common indicator of the influenza virus is a fever, often more than 100ºF (37.8ºC). It is highly contagious and in more serious cases can cause life-threatening complications. Learn other symptoms that could indicate a type B influenza infection.

There are three main types of influenza:

  • Type A. The most common form of influenza, type A can spread from animals to humans and is known to cause pandemics.
  • Type B. Similar to type A, influenza B is also highly contagious and can have dangerous effects on your health in more severe cases. However, this form can only be spread from human to human. Type B influenza can cause seasonal outbreaks and can be transferred throughout the year.
  • Type C. This type is the mildest version of the flu. If infected with type C influenza, your symptoms will not be as damaging.

Early detection of an influenza infection can prevent the virus from worsening and help you find the best course of treatment. Common symptoms of type B influenza include:

Respiratory symptoms

Similar to a common cold, influenza B can cause you to experience respiratory symptoms. Onset symptoms may include:

However, influenza respiratory symptoms may be more severe and can lead to other health complications. If you have asthma, a respiratory infection can worsen your symptoms and may even trigger an attack.

If left untreated, or in more severe cases, influenza B can cause:

Body symptoms

A common signal of the flu is a fever that could reach as high as 106ºF (41.1ºC). If your fever does not subside within a few days, seek immediate medical attention.

In addition, you may also experience symptoms including:

Stomach symptoms

In rare cases, the flu may cause diarrhea or stomach pains. These symptoms are more common in children. It can be mistaken for a stomach bug since children infected with type B influenza may experience:

  • nausea
  • vomiting
  • abdominal pain
  • loss of appetite

If you suspect you have the flu, drink plenty of fluids to prevent dehydration. Also allow yourself plenty of sleep so your body can rest and recharge.

Sometimes influenza B symptoms improve on their own. However, those who are at high risk for flu complications should seek medical treatment immediately.

High-risk groups include:

  • children under 5 years old, especially those younger than 2 years old
  • adults 65 years old and up
  • women who are pregnant or up to two weeks postpartum
  • Native Americans (American Indians and Alaska Natives)
  • people with weakened immune systems or certain chronic conditions

If your young child has the flu, seek medical treatment before resorting to home treatment. Some medications could increase their risk of complications. If your child has a fever, keep them home for at least 24 hours after the fever subsides without help from medication.

In some flu cases, your doctor may prescribe painkillers and antiviral medication to shorten illness time and prevent further complications. Doctors also recommend getting an annual flu shot to protect against common strains of the virus.

The Healthline FindCare tool can provide options in your area if you need help finding a primary care doctor or pediatrician.

Type B influenza can cause you to experience symptoms more severe than a common cold. In some cases, this infection resolves without the need for medical attention. However, if your symptoms worsen or don’t improve after a few days, schedule a visit with your doctor.