Common colds are usually caused by viruses (rhinovirus), occur occasionally and last between 7 and 10 days. Symptoms are dense nasal secretions, frequent throat ache, coughing and frequent but isolated sneezing and fever.
The cause of allergic rhinitis is sensitivity to inhaled allergens. It persists while the allergens are present in the atmosphere, which means that in general this type of rhinitis is recurring. Its symptoms include aqueous nasal secretions, nasal itching which sometimes extends to the palate, frequent sneezing, absence of fever and, more rarely, throat aches.
The allergens that cause allergic rhinitis are airborne and inhaled.