Nasal spray oil are also available. There is however no trial-verified evidence that they have a measurable effect on symptoms. Decongestant nasal sprays are available over-the-counter in many countries. They work to very quickly open up nasal passages by constricting blood vessels in the lining of the nose. Prolonged use of these types of sprays can damage the delicate mucous membranes in the nose. This causes increased inflammation, an effect known as rhinitis medicamentosa or the rebound effect. Decongestant nasal sprays are advised for short-term use only, preferably 5 to 7 days at maximum. Some doctors advise to use them 3 days
Paranasal sinuses and lower oxygen levels compared to breathing air. The paranasal sinuses are joined to the nasal cavity via small orifices called ostia. These become blocked easily by allergic inflammation, or by swelling in the nasal lining that occurs with a cold. If this happens, normal drainage of mucus within the sinuses is disrupted, and sinusitis may occur. Because the maxillary posterior teeth are close to the maxillary sinus, this can also cause clinical problems if any disease processes are present, such as an infection in any of these teeth. These clinical problems can include secondary sinusitis, the inflammation of the