Respiratory infections are classified into either upper or lower respiratory infections, depending which part of the respiratory system is affected. Upper respiratory infections are found in the higher parts of the respiratory tract, such as the sinuses, nose and throat. Lower respiratory infections on the other hand will affect the lungs and airways. Upper respiratory infections can include sinus infections, the common cold or head cold, tonsillitis, laryngitis and a mild flu. The most common symptom of an upper respiratory infection is a cough, with sore throat, sneezing, runny or stuffy nose, achy muscles and headache symptoms potentially being caused by lung infections. Lower respiratory infections are typically found in the lungs or the airways. These infections are caused by bacterial or viral infections and include a severe flu, pneumonia, whooping cough, bronchitis or tuberculosis. Symptoms of a lower respiratory infection include wheezing upon exhaling, chest tightness, shortness of breath and a severe cough that can produce phlegm. If you suspect you have a respiratory infection, seeing a doctor such as one of the physicians at Physicians Now Urgent Care can provide you with a proper diagnosis and treatment if needed.