Quercetin is a plant flavonoid with antioxidant and anti-inflammatory properties. It’s commonly found in apples, onions, and berries—but is also available as a supplement, often promoted for allergy relief and immune support.

It works by stabilizing mast cells, which release histamines—compounds that cause sneezing, itching, and watery eyes. That’s why quercetin is popular among people with seasonal allergies or chronic sinus issues.

Some products combine quercetin with bromelain (from pineapple) or vitamin C to enhance its absorption and effectiveness. It's also being studied for potential antiviral and anti-inflammatory benefits.

While quercetin is generally safe, large doses might interact with medications or cause mild digestive upset. Stick to products with transparent dosing and avoid stacking it with too many other immune supplements at once.

For insights into trusted quercetin brands and when to use them, explore wellness resources like health supplements. When allergy season hits, having the right support can make all the difference.