Our family has 5 boxes and 1 box is almost done after using it to treat a cough as well as a prophylaxis.

If you want a natural form of Quercitin… find a blackberry bush and try a blackberry leaf tea or tincture.

Blackberry Leaves and Flavonoids:

Blackberry and raspberry leaves contain a notable amount of flavonoid compounds. According to a 2004 study from the Department of Pharmacognosy, Faculty of Pharmacy, Medical University of Bialystok in Poland, these leaves contain derivatives of kaempferol and quercetin, phenolic acids, triterpenes, mineral salts and vitamin C.

Flavonoids are powerful antioxidants. They have anti-inflammatory and immune system benefits.

The best-known flavonoids are quercetin and kaempferol which blackberry leaves contain. Due to their anti-inflammatory and immune boosting benefits, blackberry leaves are used to aid in healing sore throats, mouth sores, anti-aging, diarrhea, wounds and hemorrhoids.

https://www.green-talk.com/blackberry-leaves/