A 2016 meta-analysis of 7 RCTs (825 subjects) found quercetin supplementation significantly reduced systolic blood pressure by -3.04 mmHg and diastolic blood pressure by -2.63 mmHg, with greater effects in subjects with baseline hypertension (≥140/90 mmHg). These effects are mediated by endothelial nitric oxide synthase (eNOS) activation and antioxidant reduction of superoxide that inactivates NO.

How long does quercetin take to reduce blood pressure?

Randomized trials typically show blood pressure effects within 4–8 weeks of consistent daily supplementation. Acute single-dose effects are measurable (within hours) but smaller than chronic dosing effects.

Can quercetin replace antihypertensive medication?

Quercetin's blood pressure reduction of ~3 mmHg systolic is meaningful for prevention but insufficient to replace medication in individuals with significant hypertension. It may complement medication to reduce required doses — discuss with your physician.