A nasal-nasopharyngeal irrigating and cleansing system including a cup with one or more assemblies that allow the flow and control of various irrigating, cleansing and medicinal liquids into the nasal passages. The construction of the cup provides sealing surfaces to allow the controlled flow of the liquids into the nose through either nostril without spillage. The flow of the liquid through the nasal passages removes via abrasion any virus or irritant substances that may be in the nasal passages or on the nasal membranes. According to one aspect of the invention as the liquid is dispensed, the angle of the cup to the face changes but a sealing rim on the cup wall continues to seal to the user's face as the angle of the cup to the user's face changes, allowing liquid to be drawn up into the user's nose via vacuum or gravity. A method of using the device of the invention for irrigating, cleansing and coating the nasal passages with antiviral agents or other beneficial medicines.