Wheezing is a high-pitched whistling sound made while breathing, often heard during exhalation. It occurs when the airways become narrowed or obstructed, making it difficult for air to flow in and out of the lungs. Common causes of wheezing include asthma, allergies, and respiratory infections. People of all ages can experience wheezing, but it is particularly common in children. It can be a sign of underlying health issues, such as chronic obstructive pulmonary disease (COPD) or bronchitis. If wheezing persists or is accompanied by difficulty breathing, it is important to seek medical attention.