Acute bronchitis is swelling and irritation in your child's air passages. This irritation may cause him to cough or have other breathing problems. Acute bronchitis often starts because of another illness, such as a cold or the flu. The illness spreads from your child's nose and throat to his windpipe and airways. Bronchitis is often called a chest cold. Acute bronchitis lasts about 2 weeks and is usually not a serious illness