High Quality Quercetin Supplements

Quercetin is a flavonoid found in onions, apples, and capers. It stabilizes mast cells (reducing histamine release), supports immune function, has antioxidant effects, and may help blood pressure. Often paired with vitamin C and bromelain for enhanced absorption.

500–1,000 mg/day, often split into two doses with food. Quercetin phytosome forms absorb 10–20x better than standard quercetin and use lower doses (250–500 mg/day) for similar effect.

Quercetin inhibits some CYP enzymes and can affect blood levels of certain drugs (including some chemotherapy and immunosuppressants). Talk to a clinician if you take prescription medications.

Pharmaceutical antihistamines (Zyrtec, Allegra) work faster and stronger for acute allergy symptoms. Quercetin works upstream by stabilizing mast cells — slower onset but addresses the trigger. Many use both: quercetin daily, antihistamine as needed.

Mast cell stabilization builds gradually. Most people start seeing benefit after 1–2 weeks of daily use, with maximum effect at 4–6 weeks. Start before allergy season for best results.

Capers, red onions, kale, blueberries, apples (especially the skin), broccoli, cherries, and green tea. Cooking reduces quercetin content by 30–50%, so raw or lightly cooked is best.

Some lab studies suggest quercetin has antiviral and zinc-ionophore properties. Clinical evidence is preliminary. It's commonly used in immune support stacks but shouldn't replace vaccines, antiviral medications, or other proven measures.

Bromelain (from pineapple) is often paired with quercetin because it may improve absorption and adds anti-inflammatory effects. Many quality formulas combine them. Vitamin C also enhances quercetin's antihistamine action.