Conv. Plasma
Nigella Sativa
Vitamin A
Vitamin C
Vitamin D

Home   COVID-19 treatment studies for Vitamin C  COVID-19 treatment studies for Vitamin C  C19 studies: Vitamin C  Vitamin C   Select treatmentSelect treatmentTreatmentsTreatments
Aspirin Molnupiravir
Bamlanivimab Nigella Sativa
Bromhexine Nitazoxanide
Budesonide Povidone-Iod..
Casirivimab/i.. Probiotics
Colchicine Proxalutamide
Conv. Plasma Quercetin
Curcumin Remdesivir
Favipiravir Sotrovimab
Fluvoxamine Vitamin A
Hydroxychloro.. Vitamin C
Iota-carragee.. Vitamin D
Ivermectin Zinc

Other Adoption (RCT)18%0.82 [0.53-1.27]recov. time48 (n)50 (n)CT​1Improvement, RR [CI]TreatmentControlZhao (PSM)72%0.28 [0.08-0.93]progression4/5512/55Tau​2 = 0.41; I​2 = 70.1%Early treatment46%0.54 [0.19-1.51]4/10312/10546% improvementKrishnan31%0.69 [0.47-0.92]death40/7952/73Improvement, RR [CI]TreatmentControlZhang (RCT)50%0.50 [0.20-1.50]death6/2711/29Patel29%0.71 [0.43-1.14]death22/9626/80Kumari (RCT)36%0.64 [0.26-1.55]death7/7511/75Darban (RCT)33%0.67 [0.14-3.17]progression2/103/10CT​1JamaliMog.. (RCT)0%1.00 [0.22-4.56]death3/303/30Gao86%0.14 [0.03-0.72]death1/465/30Hamidi-Ala.. (RCT)44%0.56 [0.20-1.51]death5/409/40CT​1Al Sulaiman (PSM)15%0.85 [0.61-1.12]death46/14259/142Mulhem-32%1.32 [1.07-1.62]death157/794359/2,425Gadhiya-1%1.01 [0.48-1.91]death19/5536/226Hakamifard (RCT)46%0.54 [0.14-2.08]ICU3/385/34CT​1Suna21%0.79 [0.44-1.41]death17/15324/170Li (PSM)-11%1.11 [0.79-1.54]death7/819/24Vishnuram54%0.46 [0.24-0.86]death164/8,63410/241Özgünay9%0.91 [0.63-1.30]death17/3275/128Tan25%0.75 [0.10-2.98]int./death1/4614/115CT​1Tau​2 = 0.07; I​2 = 56.6%Late treatment19%0.81 [0.67-0.99]517/10,305721/3,87219% improvementBehera10%0.90 [0.63-1.21]cases29/67157/305Improvement, RR [CI]TreatmentControlLouca0%1.00 [0.97-1.04]casesTau​2 = 0.00; I​2 = 0.0%PrEP0%1.00 [0.97-1.03]29/67157/3050% improvementAll studies14%0.86 [0.76-0.98]550/10,475890/4,28214% improvement21 vitamin C COVID-19 Sep 25, 20211 CT: study uses combined treatmentTau​2 = 0.03; I​2 = 54.7%; Z = 2.26Effect extraction pre-specifiedFavors vitamin CFavors control
Database of all vitamin C COVID-19 studies. Submit updates/corrections.
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Sep 7
Late Xia et al., Aging, doi:10.18632/aging.203503 (Peer Reviewed) High-dose vitamin C ameliorates cardiac injury in COVID-19 pandemic: a retrospective cohort study
Details   Retrospective 113 severe and critical patients in China with cardiac injury, 51 treated with high dose vitamin C, showing treatment associated with improvement of myocardial injury.
Jul 26
Late Tan et al., QJM, doi:10.1093/qjmed/hcab184 (Peer Reviewed) int./death, ↓24.5%, p=0.74 Efficacy of diammonium glycyrrhizinate combined with vitamin C for treating hospitalized COVID-19 patients: a retrospective, observational stud
Details   PSM retrospective 207 hospitalized patients in China, 46 treated with diammonium glycyrrhizinate and vitamin C, showing lower risk of ARDS with treatment.
Jul 6
PrEP Margolin et al., Journal of Evidence-Based Integrative Medicine, doi:10.1177/2515690X211026193 (Peer Reviewed) cases, ↓94.4%, p=0.003 20-Week Study of Clinical Outcomes of Over-the-Counter COVID-19 Prophylaxis and Treatment
Details   Retrospective 113 outpatients, 53 (patient choice) treated with zinc, quercetin, vitamin C/D/E, l-lysine, and Quina, showing lower cases with treatment.
Jul 4
Late Özgünay et al., The European Research Journal, doi:10.18621/eurj.938778 (Peer Reviewed) death, ↓9.3%, p=0.69 The use of vitamin C in the intensive care unit during the COVID-19 pandemic
Details   Retrospective 160 ICU patients, 32 with raised neutrophil/lymphocyte ratio treated with vitamin C, showing no significant differences.
Jun 30
Late Vishnuram et al., Indian Journal of Basic and Applied Medical Research, doi:10.36848/IJBAMR/2020/29215.55599 (Peer Reviewed) death, ↓54.2%, p=0.03 Role of high dose oral liposomal vitamin C in reducing mortality in patients with COVID-19
Details   Retrospective 8,634 hospitalized patients in India, showing lower mortality with high-dose vitamin C in unadjusted results. No group details are provided, the text and table appear to show different results, and some numbers do not match.
Jun 8
Late Li et al., Journal of Pharmacy Practice, doi:10.1177/08971900211015052 (Peer Reviewed) death, ↑10.5%, p=1.00 Use of Intravenous Vitamin C in Critically Ill Patients With COVID-19 Infection
Details   PSM retrospective 8 ICU patients treated with vitamin C and 24 matched controls, showing no significant difference. Authors note that "it is possible for the delayed timing of IV vitamin C to have blunted the beneficial effects as th..
Jun 1
Review May et al., British Journal of Pharmacology, doi:10.1111/bph.15579 (Review) (Peer Reviewed) review Therapeutic potential of megadose vitamin C to reverse organ dysfunction in sepsis and COVID-19
Details   Review of data supporting the use of megadose vitamin C as a treatment for sepsis and COVID-19.
May 11
Late Suna et al., Med. Clin. (Barc.), doi:10.1016/j.medcli.2021.04.010 (Peer Reviewed) death, ↓21.3%, p=0.52 Effect of high-dose intravenous vitamin C on prognosis in patients with SARS-CoV-2 pneumonia
Details   Retrospective 323 hospitalized patients, 153 treated with vitamin C, showing no significant differences. Patients in each group were in different time periods, with the vitamin C group first. Time based confounding is possible due to impr..
May 3
In Silico Malla et al., bioRxiv, doi:10.1101/2021.05.02.442358 (Preprint) Vitamin C inhibits SARS coronavirus-2 main protease essential for viral replication
Details   In Vitro study showing that vitamin C inhibits SARS-CoV-2 3CLpro. Authors note that the different clinical results may be explained in part by the widely varying dosages used, and they conclude that vitamin C and/or derivatives may become..
Apr 22
Early Zhao et al., Frontiers in Pharmacology, doi:10.3389/fphar.2021.638556 (Peer Reviewed) progression, ↓72.0%, p=0.03 High Dose Intravenous Vitamin C for Preventing The Disease Aggravation of Moderate COVID-19 Pneumonia. A Retrospective Propensity Matched Before-After Study
Details   PSM retrospective 110 patients, 55 treated with high-dose IV vitamin C, showing lower progression to severe disease with treatment. Patients in each group were in different time periods, time based confounding is likely due to SOC improvi..
Apr 14
Late Hakamifard et al., Immunopathologia Persa, doi:10.34172/ipp.2021.xx (Peer Reviewed) ICU, ↓46.3%, p=0.46 The effect of vitamin E and vitamin C in patients with COVID-19 pneumonia; a randomized controlled clinical trial
Details   RCT with 38 patients treated with vitamin C and vitamin E, and 34 control patients, showing lower ICU admission with treatment, but not statistically significant.
Apr 8
Late Gadhiya et al., BMJ Open, doi:10.1136/bmjopen-2020-042549 (Peer Reviewed) death, ↑0.7%, p=0.98 Clinical characteristics of hospitalised patients with COVID-19 and the impact on mortality: a single-network, retrospective cohort study from Pennsylvania state
Details   Retrospective 283 patients in the USA showing higher mortality with all treatments (not statistically significant). Confounding by indication is likely. In the supplementary appendix, authors note that the treatments were usually given fo..
Apr 7
Late Mulhem et al., BMJ Open, doi:10.1136/bmjopen-2020-042042 (Peer Reviewed) death, ↑32.2%, p=0.01 3219 hospitalised patients with COVID-19 in Southeast Michigan: a retrospective case cohort study
Details   Retrospective database analysis of 3,219 hospitalized patients in the USA. Very different results in the time period analysis (Table S2), and results significantly different to other studies for the same medications (e.g., heparin OR 3.06..
Apr 2
Late Al Sulaiman et al., Research Square, doi:10.21203/ (Preprint) death, ↓14.9%, p=0.27 Ascorbic Acid as an Adjunctive Therapy in Critically Ill Patients with COVID-19: A Multicenter Propensity Score Matched Study
Details   Retrospective 158 critically ill patients receiving vitamin C and propensity matched controls, showing mortality OR 0.77 [0.48-1.23], and statistically significantly lower thrombosis, OR 0.42 [0.18-0.94]. 1000mg of vitamin C was given dai..
Mar 8
Late Hamidi-Alamdari et al., Clinical and Translational Investigation, doi:10.24875/RIC.21000028 (Peer Reviewed) death, ↓44.4%, p=0.38 Methylene blue for treatment of hospitalized COVID-19 patients: a randomized, controlled, open-label clinical trial, phase 2
Details   RCT 80 hospitalized patients with severe COVID-19, 40 treated with methylene blue + vitamin C + N-acetyl cysteine, showing lower mortality, shorter hospitalization, and significantly improved SpO2 and respiratory distress with treatment. ..
Mar 2
Early Hemilä et al., Research Square, doi:10.21203/ (Preprint) (meta analysis) meta-analysis Vitamin C may increase the recovery rate of outpatient cases of SARS-CoV-2 infection by 70%: reanalysis of the COVID A to Z Randomized Clinical Trial
Details   Reanalysis of Thomas et al. showing that vitamin C increased the recovery rate by 70%, p = 0.025.
Feb 26
Late Gao et al., Aging, doi:10.18632/aging.202557 (Peer Reviewed) death, ↓86.0%, p=0.04 The efficiency and safety of high-dose vitamin C in patients with COVID-19: a retrospective cohort study
Details   Retrospective 76 COVID-19 patients, 46 treated with intravenous high-dose vitamin C, showing lower mortality and improved oxygen requirements with treatment. Dosage was 6g intravenous infusion per 12hr on the first day, and 6g once for th..
Feb 12
Early Thomas et al., JAMA Network Open, doi:10.1001/jamanetworkopen.2021.0369 (Peer Reviewed) recov. time, ↓17.9%, p=0.38 Effect of High-Dose Zinc and Ascorbic Acid Supplementation vs Usual Care on Symptom Length and Reduction Among Ambulatory Patients With SARS-CoV-2 Infection: The COVID A to Z Randomized Clinical Trial
Details   Small 214 low-risk outpatient RCT showing non-statistically significant faster recovery with zinc and with vitamin C. NCT04342728. A secondary analysis concludes that vitamin C increases recovery rate by 71% (p = 0.036) [1]. See also [2].
Feb 9
PrEP Hancock et al., SSRN, doi:10.2139/ssrn.3779211 (Preprint) Case Cluster of RT-PCR COVID-19 Positive Patients with an Unexpected Benign Clinical Course With Vitamin D, Melatonin, Vitamin C, and Viscum Album
Details   Case series of 24 COVID-19 patients (12 confirmed PCR+) treated with vitamin D, vitamin C, and melatonin, showing positive outcomes with no patient having worse than a mild case, including 7 high risk patients.
Feb 1
Late Zhao et al., Ann. Palliat. Med., doi:10.21037/apm-20-1387 (Peer Reviewed) Beneficial aspects of high dose intravenous vitamin C on patients with COVID-19 pneumonia in severe condition: a retrospective case series study
Details   Retrospective case study of 12 severe/critical COVID-19 patients finding that high dose IV vitamin C improved inflammatory response, immune and organ function. There was no control group.
Jan 27
Late Xing et al., Journal of Pharmaceutical and Biomedical Analysis, doi:10.1016/j.jpba.2021.113927 (Peer Reviewed) Vitamin C supplementation is necessary for patients with coronavirus disease: An ultra-high-performance liquid chromatography-tandem mass spectrometry finding
Details   Prospective study with 31 COVID-19 patients and 60 controls reporting on a new method to assess plasma vitamin C concentrations. Vitamin C was deficient (11.4µmol/l vs. 52µmol/l for healthy controls), and returned to a normal range (76µmo..
Jan 9
Late JamaliMoghadamSiahkali et al., Research Square, doi:10.21203/ (Preprint) death, 0.0%, p=1.00 Safety and Effectiveness of High-Dose Vitamin C in Patients with COVID-19; A Randomized Controlled open-label Clinical Trial
Details   Small late stage RCT for the addition of vitamin C to HCQ and lopinavir/ritonavir, with 30 treatment and 30 control patients, finding a significant reduction in temperature and a significant improvement in oxygenation after 3 days in the ..
Dec 15
Late Darban et al., Journal of Cellular & Molecular Anesthesia, doi:10.22037/jcma.v6i2.32182 (Peer Reviewed) progression, ↓33.3%, p=1.00 Efficacy of High Dose Vitamin C, Melatonin and Zinc in Iranian Patients with Acute Respiratory Syndrome due to Coronavirus Infection: A Pilot Randomized Trial
Details   Small RCT in Iran with 20 ICU patients, 10 treated with high-dose vitamin C, melatonin, and zinc, not showing significant differences. IRCT20151228025732N52.
Dec 7
Review Holford et al., Nutrients, doi:10.3390/nu12123760 (Review) (Peer Reviewed) review Vitamin C—An Adjunctive Therapy for Respiratory Infection, Sepsis and COVID-19
Details   Review of vitamin C use for respiratory infections including COVID-19 and the mechanisms of action. Authors note that evidence to date indicates oral vitamin C (2–8 g/day) may reduce the incidence and duration of respiratory infections, a..
Nov 30
Late Kumari et al., Cureus 12(11): e11779, doi:10.7759/cureus.11779 (Peer Reviewed) death, ↓36.4%, p=0.45 The Role of Vitamin C as Adjuvant Therapy in COVID-19
Details   RCT 150 hospitalized patients in Pakistan showing 26% faster recovery, p < 0.0001. 36% lower mortality, not statistically significant due to the small number of events. Dosage was 50 mg/kg/day of intravenous vitamin C.
Nov 30
PrEP Louca et al., BMJ Nutrition, Prevention & Health, doi:10.1136/bmjnph-2021-000250 (preprint 11/30/20) (Peer Reviewed) cases, 0.0%, p=1.00 Modest effects of dietary supplements during the COVID-19 pandemic: insights from 445 850 users of the COVID-19 Symptom Study app
Details   Survey analysis of dietary supplements showing no significant difference in PCR+ cases with vitamin C usage in the UK, however significant reductions were found in the US and Sweden. These results are for PCR+ cases only, they do not refl..
Nov 3
PrEP Behera et al., PLoS ONE, doi:10.1371/journal.pone.0247163 (preprint 11/3) (Peer Reviewed) cases, ↓9.6%, p=0.58 Role of ivermectin in the prevention of SARS-CoV-2 infection among healthcare workers in India: A matched case-control study
Details   Retrospective matched case-control prophylaxis study for HCQ, ivermectin, and vitamin C with 372 healthcare workers, showing lower COVID-19 incidence for all treatments, with statistical significance reached for ivermectin. HCQ OR 0.56, ..
Oct 1
Late Patel et al., Chest Infections, doi:10.1016/j.chest.2020.08.322 (Peer Reviewed) death, ↓29.5%, p=0.18 The significance of oral ascorbic acid in patients with COVID-19
Details   Retrospective 176 hospitalized patients, 96 treated with oral vitamin C (from 500mg to 1500mg daily), showing lower mortality with treatment.
Sep 8
Levels Arvinte et al., Med. Drug Discov, doi:10.1016/j.medidd.2020.100064 (Peer Reviewed) Serum Levels of Vitamin C and Vitamin D in a Cohort of Critically Ill COVID-19 Patients of a North American Community Hospital Intensive Care Unit in May 2020: A Pilot Study
Details   Pilot study with 21 ICU patients finding low serum levels of vitamin C and vitamin D in most patients. Older age and low vitamin C level appeared to be co-dependent risk factors for mortality.
Aug 26
Levels Chiscano-Camón et al., Critical Care, doi:10.1186/s13054-020-03249-y (Peer Reviewed) Vitamin C levels in patients with SARS-CoV-2-associated acute respiratory distress syndrome
Details   Small study of 18 COVID-19 ARDS patients showing that vitamin C levels were very low - 17 patients had undetectable levels and one had a low level (2.4 mg/L).
Aug 10
Late Zhang et al., Annals of Intensive Care, doi:10.1186/s13613-020-00792-3 (Peer Reviewed) death, ↓50.0%, p=0.20 Pilot Trial of High-dose vitamin C in critically ill COVID-19 patients (preprint 8/10/2020)
Details   Small RCT for high dose vitamin C for ICU patients showing reduced (but not statistically significant) mortality. Dosage was 12g of vitamin C/50ml every 12 hours for 7 days at a rate of 12ml/hour.
Aug 1
Late Hiedra et al., Expert Review of Anti-infective Therapy, doi:10.1080/14787210.2020.1794819 (Peer Reviewed) The use of IV vitamin C for patients with COVID-19: a case series
Details   Case study of 17 patients receiving IV vitamin C for COVID-19, finding a significant decrease in inflammatory markers, including ferritin and D-dimer, and a trend to decreasing FiO2 requirements, after vitamin C administration. There was ..
Jul 25
Review Feyaerts et al., Nutrition, doi:10.1016/j.nut.2020.110948 (Review) (Peer Reviewed) review Vitamin C as prophylaxis and adjunctive medical treatment for COVID-19?
Details   Review concluding that there is clear evidence that vitamin C in high doses can reduce interleukin-6 and endothelin-1 mediators. Authors suggest a relatively low dose as prophylaxis, and in cases of severe COVID-19, an (intravenous) high-..
Jul 20
Late Krishnan et al., J Clin Anesth., doi:10.1016/j.jclinane.2020.110005 (Peer Reviewed) death, ↓30.7%, p<0.0001 Clinical comorbidities, characteristics, and outcomes of mechanically ventilated patients in the State of Michigan with SARS-CoV-2 pneumonia
Details   Retrospective 152 mechanically ventilated patients in the USA showing unadjusted lower mortality with vitamin C, vitamin D, HCQ, and zinc treatment, statistically significant only for vitamin C.
Jun 19
Review Biancatelli et al., Frontiers in Immunology, doi:10.3389/fimmu.2020.01451 (Review) (Peer Reviewed) review Quercetin and Vitamin C: An Experimental, Synergistic Therapy for the Prevention and Treatment of SARS-CoV-2 Related Disease (COVID-19)
Details   Review of the evidence for the use of vitamin C and quercetin both for prophylaxis in high-risk populations and for the treatment of COVID-19 patients.
May 27
In Silico Kumar et al., VirusDisease, doi:10.1007/s13337-020-00643-6 (preprint 5/27) (Peer Reviewed) In silico virtual screening-based study of nutraceuticals predicts the therapeutic potentials of folic acid and its derivatives against COVID-19
Details   In Silico analysis finding that magnesium ascorbate, a form of Vitamin C, was found to be the top compound among 106 nutraceuticals for binding to Mpro of SARS-CoV-2.
Please send us corrections, updates, or comments. Vaccines and treatments are both extremely valuable and complementary. All practical, effective, and safe means should be used. Elimination of COVID-19 is a race against viral evolution. No treatment, vaccine, or intervention is 100% available and effective for all current and future variants. Denying the efficacy of any method increases the risk of COVID-19 becoming endemic; and increases mortality, morbidity, and collateral damage. We do not provide medical advice. Before taking any medication, consult a qualified physician who can provide personalized advice and details of risks and benefits based on your medical history and situation. Treatment protocols for physicians are available from the FLCCC.
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