Approximately 25 million people in the U.S. have asthma, according to the Asthma and Allergy Foundation of America. While that number shows how common the condition has become, the severe form is more rare. An estimate from a September 2021 study in the Journal of Asthma and Allergy found that about 9% of people with asthma meet the criteria for severe asthma. Severe asthma comes with significantly more challenges than regular asthma.