Summary of COVID-19 quercetin studies

1. Gérain et al., NASAFYTOL® supplementation in adults hospitalized with COVID-19 infection: results from an exploratory open-label randomized controlled trial

49 patient quercetin late treatment RCT: 91% lower combined mortality/ICU admission (p=0.02), 89% lower ventilation (p=0.05), 89% lower ICU admission (p=0.05), and 73% higher hospital discharge (p=0.07).
RCT 49 hospitalized COVID-19 patients, 25 treated with curcumin and quercetin, shower lower mortality/ICU admission and improved recovery with treatment. All patients received vitamin D. 336mg curcumin, 520mg quercetin, and 18μg vitamin D3 daily for 14 days. The control arm received 20μg vitamin D3 daily. Baseline fever favored treatment while vaccination favored control.
Jun 2023, Frontiers in Nutrition, https://www.frontiersin.org/articles/10.3389/fnut.2023.1137407/full, https://c19p.org/gerain

2. Rondanelli et al., Promising Effects of 3-Month Period of Quercetin Phytosome® Supplementation in the Prevention of Symptomatic COVID-19 Disease in Healthcare Workers: A Pilot Study

120 patient quercetin prophylaxis RCT: 93% fewer symptomatic cases (p=0.04).
RCT 120 healthcare workers, 60 treated with quercetin phytosome, showing lower risk of cases with treatment. Quercetin phytosome 250mg twice a day.
Jan 2022, Life, https://www.mdpi.com/2075-1729/12/1/66/htm, https://c19p.org/rondanelli

3. Di Pierro et al., Possible Therapeutic Effects of Adjuvant Quercetin Supplementation Against Early-Stage COVID-19 Infection: A Prospective, Randomized, Controlled, and Open-Label Study

152 patient quercetin early treatment RCT: 86% lower mortality (p=0.25), 94% lower ICU admission (p=0.006), and 68% lower hospitalization (p=0.003).
RCT 152 outpatients in Pakistan, 76 treated with quercetin phytosome, showing lower mortality, ICU admission, and hospitalization with treatment.
Jun 2021, Int. J. General Medicine, https://www.dovepress.com/possible-therapeutic-effects-of-adjuvant-quercetin-supplementation-aga-peer-reviewed-fulltext-article-IJGM#, https://c19p.org/dipierro

4. Tylishchak et al., Effectiveness of the quercetin use in patients with COVID-19 with concomitant type 2 diabetes mellitus

60 patient quercetin late treatment RCT: 15% shorter hospitalization (p<0.0001).
RCT 60 hospitalized COVID-19 patients with type 2 diabetes showing quercetin treatment decreased levels of inflammatory markers (interleukin-6, CRP, ferritin), reduced length of hospital stay, and improved capillaroscopy measures compared to standard care. Quercetin was administered at 0.5g intravenously once daily for 10 days. The authors hypothesize the benefits may be due to the anti-inflammatory, antioxidant and endothelium-protective effects of quercetin,
Dec 2024, Wiadomości Lekarskie, https://www.wiadomoscilekarskie.pl/Effectiveness-of-the-quercetin-use-in-patients-with-COVID-19-with-concomitant-type,191875,0,2.html, https://c19p.org/tylishchak

5. Shohan et al., The therapeutic efficacy of quercetin in combination with antiviral drugs in hospitalized COVID-19 patients: A randomized controlled trial

60 patient quercetin late treatment RCT: 86% lower mortality (p=0.24) and 32% faster recovery (p=0.04).
Small RCT with 60 severe hospitalized patients in Iran, 30 treated with quercetin, showing shorter time until discharge. All patients received remdesivir or favipiravir, and vitamin C, vitamin D, famotidine, zinc, dexamethasone, and magnesium (depending on serum levels). Quercetin 1000mg daily for 7 days. IRCT20200419047128N2.
Dec 2021, European J. Pharmacology, https://www.sciencedirect.com/science/article/pii/S0014299921007718, https://c19p.org/shohan

6. Margolin et al., 20-Week Study of Clinical Outcomes of Over-the-Counter COVID-19 Prophylaxis and Treatment

113 patient quercetin prophylaxis study: 94% fewer cases (p=0.003).
Retrospective 113 outpatients, 53 (patient choice) treated with zinc, quercetin, vitamin C/D/E, l-lysine, and quina, showing lower cases with treatment. Results are subject to selection bias and limited information on the groups is provided. See [journals.sagepub.com].
Jul 2021, J. Evidence-Based Integrative Medicine, https://journals.sagepub.com/doi/full/10.1177/2515690X211026193, https://c19p.org/margolinq

7. Arslan et al., Synergistic Effect of Quercetin and Vitamin C Against COVID-19: Is a Possible Guard for Front Liners

113 patient quercetin prophylaxis RCT: 92% fewer cases (p=0.03).
Small prophylaxis RCT with 113 patients showing fewer cases with quercetin + vitamin C + bromelain prophylaxis. Note that this paper disappeared from SSRN without explanation.
Nov 2020, SSRN, https://europepmc.org/article/ppr/ppr239932, https://c19p.org/arslan

8. Di Pierro et al., Quercetin as a possible complementary agent for early-stage COVID-19: Concluding results of a randomized clinical trial

100 patient quercetin early treatment RCT: 37% improved recovery (p=0.007) and 58% improved viral clearance (p<0.0001).
RCT 100 outpatients in Pakistan, 50 treated with quercetin phytosome, showing faster viral clearance and improved recovery with treatment. Patients in the treatment group were significantly younger (41 vs. 54).
Jan 2023, Frontiers in Pharmacology, https://www.frontiersin.org/articles/10.3389/fphar.2022.1096853/full, https://c19p.org/dipierro5

9. Khan et al., Oral Co-Supplementation of Curcumin, Quercetin, and Vitamin D3 as an Adjuvant Therapy for Mild to Moderate Symptoms of COVID-19—Results From a Pilot Open-Label, Randomized Controlled Trial

50 patient quercetin early treatment RCT: 33% improved recovery (p=0.15) and 50% improved viral clearance (p=0.009).
RCT 50 COVID+ outpatients in Pakistan, 25 treated with curcumin, quercetin, and vitamin D, showing significantly faster viral clearance, significantly improved CRP, and faster resolution of acute symptoms (p=0.154). 168mg curcumin, 260mg quercetin and 360IU cholecalciferol.
Apr 2022, Frontiers in Pharmacology, https://www.frontiersin.org/articles/10.3389/fphar.2022.898062/full, https://c19p.org/khan4q

10. Zupanets et al., Quercetin effectiveness in patients with COVID-19 associated pneumonia

200 patient quercetin late treatment RCT: 29% improved recovery (p=0.5).
RCT 200 patients in Ukraine, 99 treated with IV quercetin/polyvinylirolidone followed by oral quercetin/pectin, showing improved recovery with treatment.
Aug 2021, Zaporozhye Med. J., http://zmj.zsmu.edu.ua/article/view/231714, https://c19p.org/zupanets

11. Din Ujjan et al., The possible therapeutic role of curcumin and quercetin in the early-stage of COVID-19—Results from a pragmatic randomized clinical trial

50 patient quercetin early treatment RCT: 29% improved recovery (p=0.11) and 91% improved viral clearance (p=0.05).
Small RCT with 50 outpatients, 25 treated with curcumin, quercetin, and vitamin D, showing improved recovery and viral clearance with treatment. 168mg curcumin, 260mg, 360IU vitamin D3 daily for 14 days.
Jan 2023, Frontiers in Nutrition, https://www.frontiersin.org/articles/10.3389/fnut.2022.1023997/full, https://c19p.org/dinujjanq

12. Onal et al., Treatment of COVID-19 patients with quercetin: a prospective, single center, randomized, controlled trial

429 patient quercetin late treatment RCT: 94% lower ICU admission (p=0.39) and 78% higher hospital discharge (p=0.1).
RCT 447 moderate-to-severe hospitalized patients in Turkey, 52 treated with quercetin, bromelain, and vitamin C, showing no statistically significant difference in clinical outcomes.
Jan 2021, Turk. J. Biol.-529, https://journals.tubitak.gov.tr/biology/vol45/iss7/13/, https://c19p.org/onal

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