As with Children, upper respiratory tract infections can occur with or without sinus involvement.  Adenoids are usually not a cause of nasal congestion in adults, unless the patient is HIV positive or has a tumour in the back of the nose, for example, nasopharyngeal carcinoma. 

Allergies can happen as with children with or without polyp formation.  Septal deviation (will be covered in a separate blog) is common.  Drugs, whether topically e.g. Iliadin or Drixine or systemic e.g. anti-depressants or anti-inflamatories can cause nasal blockage.  Trauma is fairly common in adults and this can affect the nasal septum or the nasal bones. 

Tumours are fairly rare and can be benign or malignant, for instance antro-choanal polyp or if malignant squamous cell carcinoma or lymphoma.  Other infections can also involve the nose more rarely, for instance Tuberculosis