Accessible Search Form           Advanced Search

  • PRINT PAGE  |  PRINT ENTIRE TOPIC  |  SHARE

What Causes Asthma?

The exact cause of asthma isn't known. Researchers think some genetic and environmental factors interact to cause asthma, most often early in life. These factors include:

  • An inherited tendency to develop allergies, called atopy (AT-o-pe)
  • Parents who have asthma
  • Certain respiratory infections during childhood
  • Contact with some airborne allergens or exposure to some viral infections in infancy or in early childhood when the immune system is developing

If asthma or atopy runs in your family, exposure to irritants (for example, tobacco smoke) might make your airways more reactive to substances in the air.

Some factors might be more likely to cause asthma in certain people than in others. Researchers continue to explore what causes asthma.

The Hygiene Hypothesis

One theory researchers have for what causes asthma is called the hygiene hypothesis. They believe that our Western lifestyle—with its emphasis on hygiene and sanitation—has resulted in changes in our living conditions and an overall decline in infections in early childhood.

Many young children no longer have the same types of environmental exposures and infections as children did in the past. This affects the way that young children's immune systems develop during very early childhood, and it may increase their risk for atopy and asthma. This is especially true for children who have close family members with one or both of these conditions.

Rate This Content:

  
previous topic next topic

Featured Video


Asthma Awareness Google+ Hangout On Air


Asthma Clinical Trials

Clinical trials are research studies that explore whether a medical strategy, treatment, or device is safe and effective for humans. To find clinical trials that are currently underway for Asthma, visit www.clinicaltrials.gov.

Children and Clinical Studies Logo

Visit Children and Clinical Studies to hear experts, parents, and children talk about their experiences with clinical research.


Asthma in the News

February 11, 2014
NIH study seeks to improve asthma therapy for African-Americans
Researchers will enroll around 500 African-American children and adults who have asthma in a multi-center clinical trial to assess how they react to therapies and to explore the role of genetics in determining the response to asthma treatment. This new clinical study, which will take place at 30 sites in 14 states, is aimed at understanding the best approach to asthma management in African-Americans.

View all Asthma Press Releases

 
June 15, 2012 Last Updated Icon

The NHLBI updates Health Topics articles on a biennial cycle based on a thorough review of research findings and new literature. The articles also are updated as needed if important new research is published. The date on each Health Topics article reflects when the content was originally posted or last revised.

Twitter iconTwitter         Facebook iconFacebook         YouTube iconYouTube        Google+ iconGoogle+