QUERCETIN 500MG 60 COUNT We recommend using this product while we wait for our Quercetin Plus to arrive back in stock! The main ingredient (Quercetin 500mg) is identical. Recommended in all Immune Boost Protocols especially Covid. Quercetin is one of the most well-known antioxidant bioflavonoids. As a free radical scavenger, quercetin helps support healthy sinus, respiratory, and immune system function. Suggested Use 1 capsule per day or as directed by a health professional.