8 Runny nose
Similar to the bronchi, as the epithelium of the nose cavity reacts to allergen, virus or bacteria, it secretes significant amount of mucus in an attempt to “wash away” the cause. In the case of allergies and viral infections, nose secretion is clear, watery, or foamy. In case of bacterial infection, nose secretion is yellow, green or brown, often smelly and thick.
Some people experience nose congestion (inability to breathe through the nose). In such cases, using nasal decongestant is necessary to avoid complications such as middle ear inflammation or sinusitis. Keep in mind that nasal decongestants should not be used for more than seven days.