How long will it take for my allergy symptoms to improve after I start my NectarRx Allergy Drops? May 23, 2022 13:58 Updated Symptom improvement differs from patient to patient based on the severity and seasonality of their allergies. The average time is 3-6 months. Related articles Is sublingual immunotherapy safe and effective? How much does it cost? What exactly is Nectar? Is NectarRx Treatment covered by insurance? What are the ingredients?