You probably know that asthma is an illness that causes breathing problems. But what happens in the lungs when someone has an asthma flare-up? Watch this movie to find out. Back to Articles Related Articles Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor. © 1995-2021 KidsHealth®. All rights reserved. Images provided by The Nemours Foundation, iStock, Getty Images, Veer, Shutterstock, and Clipart.com.