Our natural pediatrician has always recommended quercetin (a flavonoid, which is an antioxidant) for Little-A's sinus issues. I've struggled to deal with measuring out exactly 1/4 of the adult sized capsule, and I certainly have not been able to get her to eat grapefruit. This Redd Remedies product contains vitamin C and quercetin (to normalize histamine response), bromelain and stinging nettle (anti-inflammatory properties), marshmallow root (for digestive and respiratory health), and other good stuff. It's hard to pinpoint exactly what's working and what's not when you're trying a lot of things out, but I can say that since I've put Little-A on this, her sinus issues have lessened.