1. Cold, allergies, physical damage, drug or chemical damage.

2. Alpha- antagonist- phenylephrine, corticosteroids- betamethasone, antihistamines- Loratadine, antibiotics- mupirocin, mucolytics- mensa, mast cell stabilizers- ketoifen.

3.  Decongestants cause vasoconstricion of mucosal blood vessels that reduces oedema of nasal mucosa. Local Decongestants have fewer SE eg oxymetazoline (drops). Short acting drugs have a duration of 4 to 6 hours, intermediate acting drugs have a 8 to 10 hour duration and long acting drugs have a 12 hour duration.

4. Rhinitis medicamentosa is the permanent vasoconstriction that has a poor local blood supply leading to the damage of mucosa membranes in the nose and gives permanent swelling and inflammation. Xylomethazoline may only be used for a few days cause rhinitis medicamentosa may develop.

5. 1st gen, used for rhinorrhea, 2nd gen used for allergic rhinitis. 2nd gen doesn't block muscarinic receptors and doesn't cause sedation like the first gen.

6. Corticosteroids- used for allergic rhinitis, administration is topical, anti-allergic drugs- prophylactic treatment of allergic rhinitis given as a nasal spray. Mensa- makes mucus a liquid given as a nasal spray. Normal salt solution- nasal lavage.