Allergic rhinitis is an IgE-mediated inflammation of the nasal mucosa caused by exposure to allergens like pollen, dust or foods. It affects 10-20% of the population. Symptoms include sneezing, nasal congestion and discharge. Diagnosis involves skin prick tests and measuring IgE levels. Treatment includes avoidance of triggers, immunotherapy, antihistamines, nasal steroids and surgery for nasal polyps or severe cases.