Colds or bronchitis: Especially in the fall and winter months, acute respiratory infections occur more frequently, the triggers of which are usually due to viruses, and only in rare cases to bacteria. But chronic respiratory diseases such as asthma and COPD are also among the most widespread diseases in Germany, each affecting around 7 million people. In medical terms, the respiratory tract is divided into the upper and lower airways. Together, they perform an important function: they supply the body with fresh oxygen when breathing and remove stale air. If the upper or lower respiratory tract is restricted in its function due to a disease, the well-being usually also decreases – even with a harmless cold. Colds are often harmless and self-limiting. However, if this is prolonged or recurrent, there may be a serious condition behind it.