Quercetin: Evidence for Allergies, Blood Pressure and Exercise
What trials and reviews found when quercetin supplements were tested for hay fever symptoms, blood pressure and exercise recovery, and how much weight those results can bear.
Content last updated . This page has not been medically reviewed.
Quick answer
Quercetin is a flavonol, a type of polyphenol, found in onions, kale, broccoli, apples, berries and tea. [1] As a supplement it has been tested for allergy symptoms, blood pressure and exercise. For blood pressure the pooled results show small changes. For allergies and exercise the trials are few, small and often use special formulations or amounts well above food levels. None of this shows that quercetin treats a disease; Memorial Sloan Kettering states that quercetin has not been shown to treat cancer or other diseases. [2] Longevity and senolytic claims are covered on quercetin, fisetin and senolytic supplements.
Evidence labels are explained on Antioxidants Explained. "Antioxidant" is a lab property; the effects below, where they exist, were measured in people.
What the research found
| Question | What the source found | Label |
|---|---|---|
| Blood pressure | A 2016 meta-analysis of placebo-controlled trials (7 trials, 9 treatment arms, 587 people) found reductions in systolic pressure of about 3 mm Hg and diastolic about 2.6 mm Hg. The effect was significant at 500 mg a day or more and not significant below that (study amounts; the dose difference itself was not confirmed by direct comparison). [3] A 2023 umbrella review of five meta-analyses found a smaller systolic drop (about 1.9 mm Hg), no effect on diastolic pressure, blood lipids or fasting glucose, and certainty of evidence from very low to moderate. [4] | Promising but limited |
| Hay fever (pollen allergy) | A randomized, placebo-controlled trial of 66 adults with pollen allergy used 200 mg of quercetin a day for 4 weeks in a bioavailable formulation (a study amount). Some symptom scores, including eye itching, sneezing and nasal discharge, were better than with placebo. [5] | Promising but limited |
| Allergic rhinitis, polyphenols as a group | A 2025 meta-analysis of 13 trials (823 people) of polyphenolic compounds (such as catechins or quercetin) found lower nasal symptom scores. The certainty of evidence was low to very low, and quality-of-life effects were not significant. [6] | Mixed |
| Exercise recovery | A meta-analysis of 13 studies (249 people), all but one using 1,000 mg a day, found less muscle soreness and lower creatine kinase (a muscle-damage marker) after hard exercise, but no change in IL-6 (an inflammation marker). All studies had some concerns about bias. [7] | Promising but limited |
| Endurance performance | A 2011 meta-analysis of 11 studies (254 people; median dose 1,000 mg a day for a median of 11 days) found a statistically significant but "between trivial and small" benefit. [8] | Mixed |
| COVID-19 | A meta-analysis of six trials found lower odds of hospitalization and ICU admission but no lower risk of death, and the authors said large trials are needed. [9] | Insufficient evidence |
| Quercetin plus zinc | Proper evidence not found. We did not locate a trial of the quercetin and zinc combination in the sources we read. | Insufficient evidence |
Official intake levels
No recommended intake or upper limit for quercetin is described in the sources we read. Every amount above is a study amount, not advice, and not an amount any health body recommended. Quercetin and its sugar form rutin are sold without a prescription in the US. [1]Frequently asked questions
Does quercetin work for hay fever?
One small trial in 66 adults found lower scores for some symptoms with a bioavailable formulation. A 2025 review said larger trials are needed. [5][10]
Does quercetin lower blood pressure?
Meta-analyses found small reductions, mainly in systolic pressure. Whether this changes health outcomes is unknown. [3][4]
Does quercetin improve athletic performance?
A 2011 meta-analysis found an effect between trivial and small. [8]
Is quercetin from food the same as a supplement?
Proper evidence not found. The trials above tested supplements, not foods.
Is quercetin proven for COVID-19?
No. A meta-analysis of six trials suggested fewer hospitalizations but not fewer deaths, and large trials are needed. [9]
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
How to read these results
- Allergies. A 2025 narrative review said human studies are still scarce, with only two clinical trials of quercetin alone, and that larger randomized trials are needed. [10] Most of the supporting findings come from cell and animal experiments. [10] Memorial Sloan Kettering notes lab data show an anti-inflammatory effect, including less histamine release, which is a lab result, not proof of benefit in people. [2]
- Blood pressure. Authors of the 2016 meta-analysis said more studies are needed to learn whether the change matters clinically. [3] A small drop in a marker does not show fewer heart attacks.
- Exercise. The studies were mostly in young men and ran for up to 12 weeks, so they do not tell us about older adults or long-term use. [7]
- Formulations differ. The allergy trial used a bioavailable formulation, and the COVID-19 authors suggested benefit may be greater with a formulation that increases absorption. Results do not transfer between forms. [5][9]
Safety, in brief
Quercetin may interact with medicines and may interfere with some chemotherapy, and its safety in pregnancy, children and kidney or liver disease is not established in the sources we read. [2] Read quercetin side effects, interactions and kidney cautions and medication interactions first. A clinician or pharmacist can check a product against your medicines. For allergies that cause breathing trouble, swelling or fainting, seek urgent medical care (911 in the US); a supplement is not a substitute. See allergies vs colds.
For a wider view see polyphenols, quercetin and resveratrol.
References
- Linus Pauling Institute, Oregon State University. Flavonoids (reviewed 2016). Read 2026-10-23.
- Memorial Sloan Kettering Cancer Center. Quercetin (updated October 2023). Read 2026-10-23.
- Serban MC et al. Effects of quercetin on blood pressure: systematic review and meta-analysis of randomized controlled trials. J Am Heart Assoc 2016. Read 2026-10-23.
- Quercetin supplementation and cardiometabolic outcomes: an umbrella review of meta-analyses. Phytother Res 2023. Read 2026-10-23.
- Repeated oral intake of a quercetin-containing supplement and allergic reaction: randomized, placebo-controlled trial. Eur Rev Med Pharmacol Sci 2022. Read 2026-10-23.
- Clinical effects of polyphenolic compounds on allergic rhinitis: systematic review and meta-analysis. J Allergy Clin Immunol Pract 2025. Read 2026-10-23.
- Quercetin supplementation and recovery after exercise-induced muscle damage: systematic review and meta-analysis. Biol Sport 2023. Read 2026-10-23.
- Kressler J et al. Quercetin and endurance exercise capacity: systematic review and meta-analysis. Med Sci Sports Exerc 2011. Read 2026-10-23.
- Quercetin for the treatment of COVID-19 patients: systematic review and meta-analysis. Rev Med Virol 2023. Read 2026-10-23.
- Quercetin and its lecithin-based formulation for allergic diseases: narrative review. Nutrients 2025. Read 2026-10-23.
Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.