Global Allergy Treatment Market by Type (Eye Allergy, Food Allergy, Skin Allergy, Asthma, Rhinitis, and Others), Treatment (Anti-Allergy Drugs and Immunotherapy), Dosage Form (Oral, Inhalers, Intranasal, and Others), and Distribution Channel (Hospital Pharmacies, Retail Pharmacies, Online Retailers, and Others) - by Size, Share & Trends Analysis, Drivers, Restraints, Opportunities, Applications, And Segment Forecasts, 2021 To 2028