Asthma is the most common cause of wheezing, according to Mayo Clinic. Infections, allergic reactions and physical obstructions can also cause airways to narrow, which leads to wheezing.
Certain lung conditions such as bronchiectasis, bronchiolitis and bronchitis can also lead to wheezing, Mayo Clinic explains. Bronchiectasis is a chronic lung condition in which widening of the bronchial tubes inhibits the clearing of mucus.
Other serious diseases that can cause wheezing include heart failure, emphysema, pneumonia and lung cancer, Mayo Clinic notes. Obstructive sleep apnea, in which breathing starts and stops during sleep, is another possible cause. Smokers are also more prone to wheezing than the general population.