First, diagnosis. A blocked nose may be related to a number of nasal disorders and depending on the cause may lead to a number of different treatments. Viral infection, hypertrophy of the inferior turbinates, nasal polyps, deviated septum, mass in the nose. Therefore, it is obvious that the treatment follows the appropriate diagnosis. See your ENT doc before treating yourself.
Depends. Depends on cause. Your ENT can better evaluate, but allergy is a common cause. Consider some allergy medicine to see if it improves. Don't use and get addicted to afrin (oxymetazoline) type otc sprays.