What Is Parainfluenza?

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Parainfluenza is a common virus that can cause both upper and lower respiratory infections, including colds, bronchitis, croup, and pneumonia. Despite the name, it is not related to influenza (the flu). It is caused by an entirely different virus known as the human parainfluenza virus (HPIV).

Types of Parainfluenza

There are four different types of HPIV:

  • HPIV-1: The leading cause of croup in children
  • HPIV-2: Also a common cause for croup; typically seen in autumn
  • HPIV-3: Associated with pneumonia, bronchitis, and bronchiolitis
  • HPIV-4: A less common type associated with more severe illness

Symptoms vary depending on both the viral type and individual.

Parainfluenza Symptoms

After exposure, it takes between two to seven days for symptoms to develop, the most common of which include:

  • Sore throat
  • Cough
  • Sneezing
  • Fever
  • Shortness of breath
  • Wheezing
  • Congestion
  • Ear pain
  • Chest pain
  • Lack of appetite

In most cases, symptoms are not severe and may be similar to the common cold. Sometimes, however, symptoms can progressively worsen and may lead to infections in the main bronchial tube of the lungs (bronchitis), the smaller air passages (bronchiolitis), or the lung itself (pneumonia).

Children under 18 months of age, persons with weakened immune systems, and the elderly are most at risk for severe parainfluenza symptoms. Call 911 or go to the emergency room if a person is having difficulty breathing.

Causes

As with the cold and flu, parainfluenza can be easily passed from person to person. The virus itself is quite robust and can live on surfaces for up to 10 hours. As a result, it can spread rapidly through places where people spend a lot of time in close quarters, such as daycares and elementary schools.

Parainfluenza infections are more common in the spring, summer, and fall. Most cases of parainfluenza occur in young children, but you can get it at any age.

To prevent the spread of infection, the same rules for the cold or flu apply:

  • Wash your hands after coming in contact with someone who has a cold or the flu.
  • Sanitize any objects and surfaces the ill person may have touched.
  • If you are sick, cover your mouth when you cough or sneeze.
  • If someone is sick, they should stay home and not attend school or work until they are better.

Diagnosis

In otherwise healthy people, parainfluenza is typically diagnosed by reviewing symptoms and ruling out other causes. Those with compromised immune systems may undergo additional testing to determine the strain affecting them. Your doctor may also take a throat culture or nasal swab to rule out other pathogens, such as influenza A.

After examining you and listening to your lungs, your doctor may order imaging tests, such as a chest X-ray or computed tomography (CT) scan, to check for pneumonia and determine the right course of treatment for you.

Treatment

If symptoms are mild, there is usually no need for medical intervention. In cases of fever or body aches, Tylenol (acetaminophen) or an over-the-counter cold and flu remedy may be used. (Children and adolescents should not take aspirin; read other product labels for the recommended age for use.)

For moderate to severe croup, steroids (typically dexamethasone) are given orally or intravenously. is only possible if the patient is not intubated or vomiting. Epinephrine, if given, is administered by inhalation via a nebulizer. For adults with pneumonia caused by parainfluenza, treatment is supportive (i.e., supplemental oxygen and/or ventilator support) and sometimes inhaled bronchodilators, such as albuterol, and/or corticosteroids.

Secondary pneumonia is typically be treated with antibiotics.

A Word From Verywell

Parainfluenza is more common than most people realize and, in most cases, is not of great concern. In fact, most people won't know whether they've caught a cold or HPIV—and it usually doesn't matter. However, if symptoms worsen or persist, don't hesitate to seek medical attention.

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Article Sources
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  1. Centers for Disease Control and Prevention. About Human Parainfluenza Viruses (HPIVs) Symptoms and Illnesses.

  2. NHS. How long do bacteria and viruses live outside the body?

  3. Centers for Disease Control and Prevention. Human Parainfluenza Viruses (HPIVs) Transmission. Updated October 31, 2019

  4. Bjornson C, et al. Nebulized epinephrine for croup in children. Cochrane Database Syst Rev. 2013 Oct 10;(10):CD006619. doi:10.1002/14651858.CD006619