COVID-19
Supplements studied for COVID-19.
Overview
Supplement research for COVID-19 remains mixed, with the strongest signals for Vitamin D and Zinc (WA 68; medium effect size, high evidence, high trust). Low vitamin D appears linked to greater infection and severity risk, and supplementation may help people who start deficient, including some hospitalized patients. Vitamin C (15 studies) shows very low effect size despite medium evidence; oral high doses did not clearly speed recovery in outpatients, and IV use in hospital usually did not improve outcomes.
Melatonin and N-Acetyl Cysteine (NAC) have low-trust evidence. Early melatonin studies suggest possible severity benefits, but results conflict. IV NAC did not clearly help severe cases, while one small oral study reported possible benefit. See the heatmap and evidence reviews below for condition-by-condition detail.
Effect graph
Relevant supplements
Relevant supplements sorted by DEX Score.
| Zinc | ★★★★★ | Medium |
| Vitamin D | ★★★★★ | Medium |
| Quercetin | ★★★★★ | Low |
| Melatonin | ★★★★★ | Low |
| Vitamin K | ★★★★★ | Low |
| Ginger | ★★★★★ | Low |
| Echinacea | ★★★★★ | Low |
| Ashwagandha | ★★★★★ | Low |
| Vitamin C | ★★★★★ | Very Low / None |
| L-Carnitine | ★★★★★ | Low |
| N-Acetyl Cysteine (NAC) | ★★★★★ | Very Low / None |
| Multivitamin | ★★★★★ | Very Low / None |
| Coconut Oil | ★★★★★ | Low |
| Rhodiola | ★★★★★ | Very Low / None |
| Resveratrol | ★★★★★ | Very Low / None |
| Milk Thistle | ★★★★★ | Very Low / None |
| Alpha-Lipoic Acid | ★★★★★ | Very Low / None |
Studies
Find individual evidence reviews for supplements sorted by DEX Score.
17 supplements for , and rated at least stars. All purchase bands. No minimum star filter.
Vitamin DView supplement →
Consider purchase·★★★★★
How we scored this▸
- Having low vitamin D levels increases the risk of catching COVID-19 and having a more severe illness.
- People with low vitamin D are more likely to need hospital care, intensive care, or a breathing machine.
- Taking vitamin D supplements may help reduce the chance of getting COVID-19 for people who start with low vitamin D. For those in hospital with COVID-19, vitamin D may help shorten the stay and lower the chance of needing intensive care or intubation, especially in older adults, but it does not lower the risk of death.
- Vitamin D can be taken by mouth or as a shot in different doses.
- For pregnant women, low vitamin D might be linked to worse COVID-19 symptoms.
- After recovering from COVID-19, vitamin D supplements may help with tiredness, anxiety, and certain brain functions for those who are deficient.
Browse 13 studies·12 meta-analyses
MetaEffect of vitamin D supplementation on clinical outcomes in adult patients with COVID-19: A GRADE-assessed systematic review and meta-analysis of randomized controlled trials2024n=19
A meta-analysis of 16 COVID-19 RCTs found vitamin D supplementation significantly reduced hospital length of stay by ~1.2 days but did not affect mortality or most biomarkers.
- Effect
- Benefit
- Population
- Adults
- Participants
- 19
RCTEffects of an 8-week high-dose vitamin D supplementation on fatigue and neuropsychiatric manifestations in post-COVID syndrome: A randomized controlled trial2024n=40
In 80 post-COVID patients given 60,000 IU/week vitamin D for 8 weeks, supplementation reduced fatigue and anxiety scores and improved cognition versus placebo.
- Effect
- Benefit
- Duration
- 8 weeks
- Dose
- 60000 IU/day
- Population
- COVID-19 patients
- Participants
- 40
MetaPreventive Vitamin D Supplementation and Risk for COVID-19 Infection: A Systematic Review and Meta-Analysis2024
A meta-analysis of 16 studies found preventive vitamin D supplementation associated with lower COVID-19 incidence (OR 0.40 in RCTs) and ICU admission (OR 0.32).
- Effect
- Benefit
- Population
- Adults
MetaThe Effect of Vitamin D Supplementation Post COVID-19 Infection and Related Outcomes: A Systematic Review and Meta-Analysis2024n=19
A meta-analysis of 29 COVID-19 studies found vitamin D reduced ICU admissions (OR 0.55 in RCTs) and intubation in trials, but RCT mortality benefit was not significant.
- Effect
- Benefit
- Population
- COVID-19 patients
- Participants
- 19
MetaThe impact of vitamin D administration on mortality in COVID-19 patients: a systematic review and meta-analysis of randomized controlled trials2024n=2,495
A meta-analysis of 19 COVID-19 RCTs (2,495 patients) found vitamin D supplementation reduced all-cause mortality (OR 0.72), especially in severe disease.
- Effect
- Benefit
- Population
- Adults
- Participants
- 2,495
MetaThe role of vitamin D in outcomes of critical care in COVID-19 patients: evidence from an umbrella meta-analysis of interventional and observational studies2024n=19
An umbrella meta-analysis of 13 meta-analyses found vitamin D supplementation associated with lower COVID-19 mortality in interventional and observational syntheses.
- Effect
- Benefit
- Population
- Adults
- Participants
- 19
MetaThe Effect of Vitamin D Supplementation on the Length of Hospitalisation, Intensive Care Unit Admission, and Mortality in COVID-19-A Systematic Review and Meta-Analysis2023n=19
A meta-analysis of 13 COVID-19 RCTs found high-dose vitamin D may shorten hospital stay and reduce ICU admission, but mortality benefit did not reach significance.
- Effect
- Benefit
- Population
- COVID-19 patients
- Participants
- 19
MetaThe role of vitamin D in the prevention and treatment of SARS-CoV-2 infection: A meta-analysis of randomized controlled trials2023n=8,128
A meta-analysis of 25 SARS-CoV-2 RCTs found vitamin D did not conclusively prevent infection but reduced ICU admission and mechanical ventilation; mortality fell in deficient patients.
- Effect
- Benefit
- Population
- COVID-19 patients
- Participants
- 8,128
MetaThe Vitamin D Serum Levels in Pregnant Women Affected by COVID-19: A Systematic Review and Meta-Analysis2023
A meta-analysis found pregnant women with COVID-19 had lower vitamin D levels with greater disease severity, supporting prenatal vitamin D monitoring and supplementation.
- Effect
- Benefit
- Population
- Women
MetaAssociation between Vitamin D Status and Risk of Developing Severe COVID-19 Infection: A Meta-Analysis of Observational Studies2022n=3,637
A meta-analysis of 24 observational COVID-19 studies (3,637 patients) found low vitamin D associated with higher severe COVID-19 and mortality risk (RR 1.50–1.60).
- Effect
- Benefit
- Population
- Hypertensive patients
- Participants
- 3,637
- Ages
- 18+
MetaEffects of Vitamin D Supplementation on COVID-19 Related Outcomes: A Systematic Review and Meta-Analysis2022n=19
A meta-analysis found vitamin D did not prevent COVID-19 infection but was associated with reduced ICU admission (RR 0.35) and mortality (RR 0.46) in infected patients.
- Effect
- Benefit
- Population
- COVID-19 patients
- Participants
- 19
MetaVitamin D supplementation for the treatment of COVID-19: A systematic review and meta-analysis of randomized controlled trials2022n=657
A meta-analysis of 8 COVID-19 RCTs (657 patients) found vitamin D did not significantly improve mortality or clinical outcomes, though repeated dosing showed nonsignificant trends.
- Effect
- No Benefit
- Population
- COVID-19 patients
- Participants
- 657
MetaLow vitamin D levels do not aggravate COVID-19 risk or death, and vitamin D supplementation does not improve outcomes in hospitalized patients with COVID-19: a meta-analysis and GRADE assessment of cohort studies and RCTs2021
A GRADE meta-analysis of 11 cohort and 2 RCT COVID-19 studies found vitamin D deficiency not significantly linked to infection or death; supplementation did not improve hospitalized outcomes.
- Effect
- No Benefit
- Population
- COVID-19 patients
ZincView supplement →
Consider purchase·★★★★★
How we scored this▸
- Zinc is possibly effective for COVID-19.
Browse 3 studies·2 meta-analyses
RCTTwice-Daily Oral Zinc in the Treatment of Patients With Coronavirus Disease 2019: A Randomized Double-Blind Controlled Trial2023n=239
In 470 COVID-19 patients, twice-daily oral zinc for 15 days lowered 30-day ICU admission (5.2% vs 11.3%) and composite bad outcomes versus placebo, shortened hospital stay by 3.5 days, and reduced symptom duration by 1.9 days in outpatients.
- Effect
- Benefit
- Duration
- 15 days
- Population
- Adults
- Participants
- 239
ObservationalZinc Supplementation Associated With a Decrease in Mortality in COVID-19 Patients: A Meta-Analysis2023n=391
A meta-analysis of five studies found zinc supplementation associated with reduced COVID-19 mortality (RR 0.63) but two studies in 391 patients showed no significant effect on symptomatology.
- Effect
- Benefit
- Dose
- 11 mg/day
- Population
- COVID-19 patients
- Participants
- 391
MetaThe effect of zinc supplementation on the course of COVID-19 - A systematic review and meta-analysis2022n=19
A meta-analysis of nine studies found zinc supplementation associated with lower in-hospital COVID-19 mortality (21.6% vs 23.0%, OR 0.71) and no increase in acute kidney injury or mechanical ventilation needs.
- Effect
- Benefit
- Population
- COVID-19 patients
- Participants
- 19
MelatoninView supplement →
Reconsider purchase·★★★★★
How we scored this▸
- Early studies suggest that taking melatonin by mouth might help reduce the severity of COVID-19, but the results are mixed. Some studies show that melatonin can help people get better faster, leave the hospital sooner, and survive more often compared to not taking it. The doses used in studies vary widely, from 2 to 24 mg a day, and treatment usually lasts one to two weeks.
- For people with mild to moderate COVID-19 not needing hospital care, melatonin 10 mg a day slightly speeded up recovery and improved quality of life, though it’s not clear how meaningful this is. In hospitalized patients with less severe illness, melatonin helped reduce hospital stay time by a few days and lowered the chance of ongoing cough, breathlessness, and tiredness. In severe cases, melatonin was shown to reduce dangerous complications like blood clots and sepsis, and helped lower death rates. However, some studies found no benefit, which might be related to lower doses or shorter treatment times.
Browse 6 studies·1 meta-analysis
RCTEfficacy and safety of oral melatonin in patients with severe COVID-19: a randomized controlled trial2023n=226
An RCT of 226 severe COVID-19 patients found oral melatonin reduced mortality (67% vs 94%), intubation need (51% vs 71%), and hospital stay (15 vs 21 days) vs standard care.
- Effect
- Benefit
- Population
- COVID-19 patients
- Participants
- 226
- Avg age
- ~54.6±11.5
RCTA Pilot of a Randomized Control Trial of Melatonin and Vitamin C for Mild-to-Moderate COVID-192022n=34
A pilot RCT of 98 mild-to-moderate COVID-19 patients found 10 mg/day melatonin for 14 days accelerated symptom resolution and improved quality of life vs placebo and vitamin C.
- Effect
- Benefit
- Duration
- 14 days
- Dose
- 10 mg/day
- Population
- COVID-19 patients
- Participants
- 34
- Avg age
- ~52
RCTEfficacy of a Low Dose of Melatonin as an Adjunctive Therapy in Hospitalized Patients with COVID-19: A Randomized, Double-blind Clinical Trial2022n=20
An RCT of 44 hospitalized COVID-19 patients found 3 mg melatonin three times daily for 14 days improved cough, dyspnea, fatigue, and CRP vs standard care alone.
- Effect
- Benefit
- Duration
- 14 days
- Dose
- 3 mg/day
- Population
- COVID-19 patients
- Participants
- 20
- Ages
- 18+
RCTMelatonin effects on sleep quality and outcomes of COVID-19 patients: An open-label, randomized, controlled trial2022n=48
An open-label RCT of 96 hospitalized COVID-19 patients found melatonin significantly improved sleep quality (LSEQ scores) and blood oxygen saturation (95.8% vs 93.7%) vs standard care.
- Effect
- Benefit
- Population
- COVID-19 patients
- Participants
- 48
RCTThe Effect of Melatonin on Thrombosis, Sepsis and Mortality Rate in COVID-19 Patients2022n=158
An RCT of 158 hospitalized COVID-19 patients found 10 mg/day melatonin for 14 days significantly reduced thrombosis and sepsis incidence and lowered mortality vs standard care.
- Effect
- Benefit
- Duration
- 14 days
- Dose
- 10 mg/day
- Population
- Adults
- Participants
- 158
MetaThe safety and efficacy of melatonin in the treatment of COVID-19: A systematic review and meta-analysis2022n=70
A meta-analysis of 6 COVID-19 RCTs (338 patients) found melatonin adjuvant therapy improved overall effective rate (OR 3.05) vs control, though CRP, SaO2, and WBC differences were not significant.
- Effect
- Benefit
- Population
- COVID-19 patients
- Participants
- 70
QuercetinView supplement →
Reconsider purchase·★★★★★
How we scored this▸
- A review of six studies shows that taking quercetin (260–1000 mg daily for up to a month) along with usual COVID-19 treatments lowers the chance of needing ICU care by about 70% and hospitalization by about 75%, but does not lower death rates or speed recovery.
- In mild COVID patients treated at home, small studies showed that quercetin 200 mg two or three times daily for 2–4 weeks helped symptoms go away faster, but results on preventing hospitalization or death were mixed. Another recent study found higher doses of quercetin (500 mg three times daily, then 500 mg twice daily) doubled the rate of becoming symptom-free and testing negative after 1 week.
- For patients with severe COVID not yet in ICU, taking quercetin 500 mg twice daily with remdesivir or favipiravir shortened hospital stay by about 1.5 days and reduced tiredness, but did not improve other symptoms or survival.
Browse 5 studies·1 meta-analysis
Open-labelQuercetin as a possible complementary agent for early-stage COVID-19: Concluding results of a randomized clinical trial2023n=50
In 100 outpatients with early COVID-19, quercetin phytosome for 2 weeks accelerated viral clearance (34 vs 12 negative by week 1) and symptom resolution versus standard care.
- Effect
- Benefit
- Duration
- 2 weeks
- Dose
- 500 mg quercetin (TDS week 1, BDS week 2)
- Population
- Pregnant women
- Participants
- 50
MetaQuercetin for the treatment of COVID-19 patients: A systematic review and meta-analysis2023n=19
A meta-analysis of 6 COVID-19 RCTs found quercetin reduced ICU admission (OR 0.31) and hospitalization (OR 0.25) but not mortality or no-recovery rate.
- Effect
- Benefit
- Population
- COVID-19 patients
- Participants
- 19
RCTThe therapeutic efficacy of quercetin in combination with antiviral drugs in hospitalized COVID-19 patients: A randomized controlled trial2022n=19
In 60 hospitalized severe COVID-19 patients, quercetin 1000 mg/day plus antivirals for 7 days lowered ALP, q-CRP, and LDH versus antivirals alone.
- Effect
- Benefit
- Duration
- 7 days
- Dose
- 1000 mg/day
- Population
- Pregnant women
- Participants
- 19
Open-labelPossible Therapeutic Effects of Adjuvant Quercetin Supplementation Against Early-Stage COVID-19 Infection: A Prospective, Randomized, Controlled, and Open-Label Study2021n=19
In 152 early COVID-19 outpatients, quercetin phytosome 1000 mg/day for 30 days reduced hospitalization, oxygen need, ICU admission, and deaths versus standard care alone.
- Effect
- Benefit
- Duration
- 30 days
- Dose
- 1000 mg/day
- Participants
- 19
Open-labelPotential Clinical Benefits of Quercetin in the Early Stage of COVID-19: Results of a Second, Pilot, Randomized, Controlled and Open-Label Clinical Trial2021n=12
In 42 early COVID-19 outpatients, quercetin phytosome add-on cleared SARS-CoV-2 faster (16/21 negative by week 1 vs 2/21 control) and lowered LDH, ferritin, CRP, and D-dimer.
- Effect
- Benefit
- Duration
- 1 week
- Population
- COVID-19 outpatients
- Participants
- 12
AshwagandhaView supplement →
Reconsider purchase·★★★★★
How we scored this▸
- It is uncertain if ashwagandha alone helps with COVID-19.
- Studies of herbal mixtures containing ashwagandha and other herbs showed that taking these combinations might shorten how long symptoms last by less than a day to about six days and reduce some symptoms like cough and fatigue.
- The improvements were small, and it’s unclear if ashwagandha itself caused the benefits.
Browse 3 studies
RCTAshwagandha (Withania somnifera) and Shunthi (Zingiber officinale) in mild and moderate COVID-19: An open-label randomized controlled exploratory trial2023n=60
In 60 mild-to-moderate COVID-19 patients over 15 days, ashwagandha 500 mg plus ginger sped clinical recovery and was safe as add-on care versus standard treatment alone.
- Effect
- Benefit
- Duration
- 15 days
- Dose
- 500 mg/day
- Participants
- 60
RCTSafety and efficacy of COROPROTECT kit as an add-on therapy in the management of mild-to-moderate COVID-19: A randomized, placebo-controlled trial2023n=300
In 300 COVID-19 patients over 10 days, the Ayurvedic COROPROTECT kit (including ashwagandha) accelerated RT-PCR negativity, lowered inflammatory markers, and improved symptoms versus standard care.
- Effect
- Benefit
- Duration
- 10 days
- Population
- COVID-19 patients
- Participants
- 300
RCTPhase III randomized clinical trial of BV-4051, an Ayurvedic polyherbal formulation in moderate SARS-CoV-2 infections and its impact on inflammatory biomarkers2022n=19
In 19 COVID-19 outpatients over 14 days, Ayurvedic polyherbal BV-4051 including ashwagandha improved symptoms as an adjunct to standard care in a phase III trial.
- Effect
- Benefit
- Duration
- 14 days
- Population
- COVID-19 patients
- Participants
- 19
EchinaceaView supplement →
Reconsider purchase·★★★★★
How we scored this▸
- No summary is available.
Browse 3 studies
RCTInvestigating the effect of echinacea extraction syrup on the outcomes of lower respiratory infections in patients with COVID-19: a randomized clinical trial study2024n=20
In 40 hospitalized COVID-19 patients over 5 days, adding echinacea syrup to standard care did not significantly improve oxygen saturation, lung involvement, or cough versus control, though WBC fell in the echinacea group.
- Effect
- No Benefit
- Duration
- 5 days
- Population
- Healthy adults
- Participants
- 20
RCTPotential Anti-Inflammatory and Anti-Fatigue Effects of an Oral Food Supplement in Long COVID Patients2024
In long COVID patients over 2 months, an oral supplement with E. angustifolia, rosehip, propolis, royal jelly, and zinc significantly reduced inflammatory markers (NLR, MLR, CRP) and fatigue versus placebo.
- Effect
- Benefit
- Duration
- 2 months
- Population
- Long COVID patients
Open-labelEchinacea Purpurea For the Long-Term Prevention of Viral Respiratory Tract Infections During Covid-19 Pandemic: A Randomized, Open, Controlled, Exploratory Clinical Study2022n=120
In 120 healthy adults over ~6 months, daily 2,400 mg E. purpurea reduced any viral RTI (RR 0.68) and SARS-CoV-2 positivity (RR 0.37, p = 0.03) versus control, with fewer fever days during acute treatment.
- Effect
- Benefit
- Dose
- 2400 mg/day
- Population
- Healthy adults
- Participants
- 120
- Ages
- 18–75
GingerView supplement →
Reconsider purchase·★★★★★
How we scored this▸
- It’s unclear if ginger helps with COVID-19.
- In one hospital study, patients without symptoms left 2–3 days sooner with ginger, but the study wasn’t reliable.
- In another study at home, sick patients saw no benefit.
- Herbal mixes with ginger slightly shortened recovery, but didn’t clear the virus or improve test results.
- Overall, research is too limited to recommend ginger as a treatment.
Browse 4 studies
RCTThe efficacy and safety of ginger (Zingiber officinale) rhizome extract in outpatients with COVID-19: A randomized double-blind placebo-control clinical trial2024n=84
In 84 outpatients with COVID-19, ginger 1000 mg three times daily for 7 days did not significantly accelerate viral clearance or improve clinical symptoms versus placebo.
- Effect
- No Benefit
- Duration
- 7 days
- Dose
- 3000 mg/day
- Population
- COVID-19 patients
- Participants
- 84
RCTAshwagandha (Withania somnifera) and Shunthi (Zingiber officinale) in mild and moderate COVID-19: An open-label randomized controlled exploratory trial2023n=60
In 60 mild-to-moderate COVID-19 patients over 15 days, ashwagandha 500 mg plus ginger sped clinical recovery and was safe as add-on care versus standard treatment alone.
- Effect
- Benefit
- Duration
- 15 days
- Dose
- 500 mg/day
- Participants
- 60
RCTPhase III randomized clinical trial of BV-4051, an Ayurvedic polyherbal formulation in moderate SARS-CoV-2 infections and its impact on inflammatory biomarkers2023n=19
In 19 COVID-19 outpatients over 14 days, Ayurvedic polyherbal BV-4051 including ashwagandha improved symptoms as an adjunct to standard care in a phase III trial.
- Effect
- Benefit
- Duration
- 14 days
- Population
- COVID-19 patients
- Participants
- 19
RCTGinger supplement significantly reduced length of hospital stay in individuals with COVID-192022n=132
In 227 hospitalized COVID-19 patients, ginger 1.5 g twice daily significantly reduced length of hospital stay versus standard care alone in a randomized trial.
- Effect
- Benefit
- Dose
- 1.5 g 2×/day
- Population
- Adults
- Participants
- 132
- Avg age
- ~60
Vitamin KView supplement →
Reconsider purchase·★★★★★
How we scored this▸
- Evidence is insufficient for this condition.
Browse 1 study·1 meta-analysis
MetaLow vitamin K status is a potential risk factor for COVID-19 infected patients: a systematic review and meta-analysis2025n=19
In a meta-analysis of 19 participants, supplementation of vitamin K during COVID-19 infection may potentially mitigate the progression toward severe infection, necessitating further support from clinical data.
- Population
- COVID-19 patients
- Participants
- 19
L-CarnitineView supplement →
Reconsider purchase·★★★★★
How we scored this▸
- Early studies in people hospitalized with mild to moderate COVID-19 found that taking L-carnitine three times a day for 5 days did not reduce fever or cough but may help improve oxygen levels and reduce inflammation.
- In people with mild or no symptoms, taking L-carnitine did not stop lung problems overall, though some had lung improvements after a week or two.
- It did not prevent COVID-19 in people exposed to the virus by living with infected individuals.
- More research is needed to confirm these findings.
Browse 2 studies
RCTA randomized clinical trial to evaluate the efficacy of L-carnitine L-tartrate to modulate the effects of SARS-CoV-2 infection2023n=122
A phase II randomized, double-blind, placebo-controlled trial in two cohorts (101 uninfected cohabitants and 122 SARS-CoV-2 positive individuals) showed that daily 2 g L-carnitine L-tartrate for 21 days was well tolerated, reduced fibrinogen and improved CT scan lung lesion outcomes in the SARS-CoV-2 positive cohort.
- Effect
- Benefit
- Duration
- 21 days
- Dose
- 2 g/day
- Population
- Adults
- Participants
- 122
- Ages
- 18–85
RCTEffects of L-carnitine supplementation in patients with mild-to-moderate COVID-19 disease: a pilot study2022n=43
A single-center randomized clinical trial in 75 hospitalized patients with mild to moderate COVID-19 found that 3 g/day oral L-carnitine for five days improved oxygen saturation, reduced ESR and CRP, ALP and LDH levels, and saw no deaths in the treatment group (versus 14% mortality in control).
- Effect
- Benefit
- Dose
- 3 g/day
- Population
- Pregnant women
- Participants
- 43
Vitamin CView supplement →
Reconsider purchase·★★★★★
How we scored this▸
- Taking high doses of vitamin C by mouth does not seem to help people with COVID-19 who are not in the hospital get better faster.
- Studies giving people 8 grams or 1 gram of vitamin C daily, sometimes with zinc, did not reduce symptoms or improve how they felt.
- For people in hospital, giving vitamin C through an IV in large doses usually does not help organs work better or improve survival, but some studies show a small benefit in lowering the chance of dying.
- Vitamin C might also make ICU stays longer.
- For people with long COVID, early research shows vitamin C combined with another supplement may reduce tiredness and help walking ability, but it is not clear if vitamin C alone is helpful.
- The overall benefit of vitamin C for COVID-19 is still unclear.
Browse 15 studies·2 meta-analyses
MetaThe Efficacy of Multivitamin, Vitamin A, Vitamin B, Vitamin C, and Vitamin D Supplements in the Prevention and Management of COVID-19 and Long-COVID: An Updated Systematic Review and Meta-Analysis of Randomized Clinical Trials2024
A meta-analysis found vitamin and multivitamin supplementation did not consistently reduce COVID-19 severity or mortality across trials.
- Effect
- No Benefit
- Population
- Women
RCTIntravenous Vitamin C for Patients Hospitalized With COVID-19: Two Harmonized Randomized Clinical Trials2023n=1,022
Two coordinated RCTs in hospitalized COVID-19 patients found that intravenous vitamin C did not significantly improve primary clinical outcomes, though some secondary measures showed small, non-definitive trends toward benefit. Two prospectively harmonised clinical trials including 1568 critically ill and 1022 non-critically COVID-19 patients, found that vitamin C (4,000 mg Intravenous vitamin C every 6 hours for 96 hours) was associated with fewer organ support-free days compared to placebo (increased duration on life-support). Among non-critically ill patients, the rate of survival to hospital discharge was 85.1% for the vitamin C group vs. 86.6% for the control group. Among critically ill patients, survival to hospital discharge was 61.9% for the vitamin C group vs. 64.6% for the control group.
- Effect
- No Benefit
- Duration
- 96 hours
- Population
- Critically ill patients
- Participants
- 1,022
- Ages
- 50–70
RCTA Pilot of a Randomized Control Trial of Melatonin and Vitamin C for Mild-to-Moderate COVID-192022n=34
A pilot RCT of 98 mild-to-moderate COVID-19 patients found 10 mg/day melatonin for 14 days accelerated symptom resolution and improved quality of life vs placebo and vitamin C.
- Effect
- No Benefit
- Duration
- 14 days
- Dose
- 10 mg/day
- Population
- COVID-19 patients
- Participants
- 34
- Avg age
- ~52
RCTEffects of l-Arginine Plus Vitamin C Supplementation on Physical Performance, Endothelial Function, and Persistent Fatigue in Adults with Long COVID: A Single-Blind Randomized Controlled Trial2022n=50
An RCT in 46 adults with long COVID found l-arginine plus 500 mg vitamin C twice daily for 28 days improved walk distance and reduced fatigue.
- Effect
- Benefit
- Duration
- 28 days
- Dose
- 1.66 g l-arginine + 500 mg vitamin C, 2×/day
- Population
- Women
- Participants
- 50
- Ages
- 20–60
ObservationalHigh-dose intravenous vitamin C decreases rates of mechanical ventilation and cardiac arrest in severe COVID-192022n=19
An observational study in severe COVID-19 found high-dose IV vitamin C associated with lower mechanical ventilation and cardiac arrest rates.
- Effect
- Benefit
- Population
- Patients With Severe Covid-19
- Participants
- 19
- Ages
- 18+
RCTPharmacologic Ascorbic Acid as Early Therapy for Hospitalized Patients with COVID-19: A Randomized Clinical Trial2022n=66
An RCT in 66 hospitalized COVID-19 patients found high-dose IV ascorbic acid did not meet the primary 72-hour clinical improvement endpoint.
- Effect
- No Benefit
- Population
- Pregnant women
- Participants
- 66
MetaVitamin C Supplementation for the Treatment of COVID-19: A Systematic Review and Meta-Analysis2022n=19
A meta-analysis of 19 COVID-19 trials found vitamin C reduced in-hospital mortality (OR 0.59 in RCTs) but lengthened ICU stay.
- Effect
- Benefit
- Population
- COVID-19 patients
- Participants
- 19
RCTAn investigation into the Effects of Intravenous Vitamin C on Pulmonary CT Findings and Clinical Outcomes of Patients with COVID-19 Pneumonia: A Randomized Clinical Trial2021n=26
An RCT in 44 COVID-19 pneumonia patients found IV vitamin C improved oxygen saturation, respiratory rate, and lung CT findings versus standard care.
- Effect
- Benefit
- Duration
- 5 days
- Dose
- 2 g/day
- Population
- Patients With Covid 19 Pneumonia A
- Participants
- 26
Clinical trialAscorbic acid as an adjunctive therapy in critically ill patients with COVID-19: a propensity score matched study2021n=739
A propensity-matched study of 739 critically ill COVID-19 patients found adjunctive ascorbic acid did not lower mortality but reduced thrombosis.
- Effect
- No Benefit
- Population
- Adults
- Participants
- 739
RCTEffect 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 Trial2021n=214
An open-label, non-placebo controlled study including 214 patients with COVID-19 assigned either zinc gluconate (50 mg/day for 10 days), vitamin C (8 g/day for 10 days), a combination of zinc gluconate and vitamin c or standard care, found no treatment led to significant changes in COVID symptom duration as measured by the number of days required to reach a 50% reduction in symptoms including fever, cough, shortness of breath and fatigue. The group taking vitamin c only, had a significantly increased rate of nausea, diarrhea and stomach cramps.
- Effect
- No Benefit
- Duration
- 10 days
- Dose
- 50 mg/day
- Population
- Women
- Participants
- 214
- Ages
- 18+
RCTPilot trial of high-dose vitamin C in critically ill COVID-19 patients2021n=19
A pilot RCT in 56 critically ill COVID-19 patients found 12 g/day IV vitamin C did not improve ventilator-free days but improved PaO2/FiO2.
- Effect
- No Benefit
- Duration
- 7 days
- Dose
- 12 g/day
- Population
- Critically ill patients
- Participants
- 19
RCTThe Effect of Vitamin C on Pathological Parameters and Survival Duration of Critically Ill Coronavirus Disease 2019 Patients: A Randomized Clinical Trial2021n=69
An RCT in 120 critically ill COVID-19 patients found 500 mg/day vitamin C for 14 days improved survival duration but not glucose or kidney function.
- Effect
- Benefit
- Duration
- 14 days
- Dose
- 500 mg vitamin C/day
- Population
- Critically ill patients
- Participants
- 69
- Ages
- 35–75
Open-labelTherapies to Prevent Progression of COVID-19, Including Hydroxychloroquine, Azithromycin, Zinc, and Vitamin D3 With or Without Intravenous Vitamin C: An International, Multicenter, Randomized Trial2021n=236
An international RCT in 237 hospitalized COVID-19 patients reported 99.6% recovery; adding IV vitamin C shortened time to discharge (15 vs 45 days).
- Effect
- Benefit
- Duration
- 14 days
- Dose
- 3 g/day
- Population
- Patients With Covid-19
- Participants
- 236
- Ages
- 22–99
RCTVitamin 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 Trial2021n=520
A reanalysis of the COVID A to Z trial reported high-dose vitamin C may increase outpatient SARS-CoV-2 recovery rate; original abstract provided limited detail.
- Duration
- 3 weeks
- Dose
- 6–8 g/day
- Population
- Children
- Participants
- 520
RCTThe Role of Vitamin C as Adjuvant Therapy in COVID-192020n=19
An RCT in COVID-19 patients found IV vitamin C (50 mg/kg/day) shortened symptom resolution and hospital stay but did not reduce mortality.
- Effect
- Benefit
- Dose
- 50 mg/kg
- Population
- COVID-19 patients
- Participants
- 19
Coconut OilView supplement →
Reconsider purchase·★★★★★
How we scored this▸
- It is not clear if taking virgin coconut oil by mouth helps people with COVID-19.
- Two small studies in the Philippines showed that adding coconut oil to regular treatment did not help patients recover faster or reduce the length of hospital stay.
Browse 2 studies
RCTVirgin coconut oil (VCO) supplementation relieves symptoms and inflammation among COVID-19 positive adults: a single-blind randomized trial2024n=19
A single-blind RCT in 76 RT-PCR-confirmed COVID-19 adults found VCO recipients were symptom-free with normal CRP by day 14, versus day 23 for symptoms and day 25 for CRP in controls.
- Effect
- Benefit
- Population
- Adults
- Participants
- 19
- Ages
- 20+
Open-labelVirgin Coconut Oil as Adjunctive Therapy for Hospitalized COVID-19 Patients in a Tertiary Referral Hospital: A Randomized Controlled Trial2024n=39
In 77 hospitalized COVID-19 patients, adjunct virgin coconut oil reduced abnormal CRP at treatment end (RR 0.75) but did not shorten hospital stay or symptom resolution and caused more adverse events.
- Effect
- No Benefit
- Population
- COVID-19 patients
- Participants
- 39
MultivitaminView supplement →
Reconsider purchase·★★★★★
How we scored this▸
- It’s not clear if taking multivitamins helps treat COVID-19.
- In one large study of adults under 60 with COVID-19 or similar symptoms, taking a daily multivitamin with minerals plus zinc (25 mg) and melatonin (2 mg) helped about 17% more people feel better by day 5, and 13% more by day 10, compared to those taking a placebo.
- By days 15 and 30, there was no difference.
- The study didn’t say how long people took the supplements, and it’s unknown which ingredient, or the combination, caused the benefit.
Browse 4 studies·1 meta-analysis
RCTMelatonin, vitamins and minerals supplements for the treatment of Covid-19 and Covid-like illness: A prospective, randomized, double-blind multicenter study2024n=164
An RCT of 164 COVID-19 patients found melatonin plus vitamin/mineral supplements did not significantly improve clinical outcomes versus standard care.
- Effect
- No Benefit
- Dose
- 25 mg
- Population
- ALL patients
- Participants
- 164
RCTPreventive Intake of a Multiple Micronutrient Supplement during Mild, Acute SARS-CoV-2 Infection to Reduce the Post-Acute COVID-19 Condition: A Double-Blind, Placebo-Controlled, Randomized Clinical Trial2024n=285
A 2-week RCT of 285 adults found preventive multivitamin intake during mild acute SARS-CoV-2 infection did not significantly shorten symptom duration versus control.
- Effect
- No Benefit
- Duration
- 2 weeks
- Population
- Women
- Participants
- 285
- Ages
- 50+
MetaThe Efficacy of Multivitamin, Vitamin A, Vitamin B, Vitamin C, and Vitamin D Supplements in the Prevention and Management of COVID-19 and Long-COVID: An Updated Systematic Review and Meta-Analysis of Randomized Clinical Trials2024
A meta-analysis found vitamin and multivitamin supplementation did not consistently reduce COVID-19 severity or mortality across trials.
- Effect
- No Benefit
- Population
- Women
RCTThe effect of supplementation with vitamins A, B, C, D, and E on disease severity and inflammatory responses in patients with COVID-19: a randomized clinical trial2021n=30
A 7-day RCT of COVID-19 outpatients found vitamins A, B, C, D, and E supplementation did not significantly reduce disease severity versus control.
- Effect
- No Benefit
- Duration
- 7 days
- Dose
- 25000 IU/day
- Population
- COVID-19 patients
- Participants
- 30
- Ages
- 20–60
N-Acetyl Cysteine (NAC)View supplement →
Reconsider purchase·★★★★★
How we scored this▸
- Small studies show that intravenous N-acetylcysteine (NAC) does not help prevent breathing failure, reduce ICU stay, or lower death rates in severe COVID-19 patients.
- However, one small study found that taking NAC by mouth for 10 days lowered the risk of severe breathing problems and death in hospitalized patients with serious COVID-19.
- More research is needed to confirm if oral NAC is beneficial for coronavirus.
Browse 5 studies·1 meta-analysis
MetaN-acetylcysteine efficacy in patients hospitalized with COVID-19 pneumonia: a systematic review and meta-analysis2023n=20,826
A meta-analysis of hospitalized COVID-19 pneumonia patients found NAC was associated with lower mortality and improved oxygenation in pooled data.
- Effect
- Benefit
- Population
- COVID-19 patients
- Participants
- 20,826
RCTA pilot study on intravenous N-Acetylcysteine treatment in patients with mild-to-moderate COVID19-associated acute respiratory distress syndrome2021n=19
A pilot RCT of 19 mild-to-moderate COVID-19 patients found IV NAC improved inflammatory markers and symptom recovery versus standard care.
- Effect
- No Benefit
- Dose
- 40 mg/day
- Population
- COVID-19 patients
- Participants
- 19
RCTDouble-blind, Randomized, Placebo-controlled Trial With N-acetylcysteine for Treatment of Severe Acute Respiratory Syndrome Caused by Coronavirus Disease 2019 (COVID-19)2021n=16
A double-blind RCT found high-dose IV NAC (300 mg/kg) did not significantly improve clinical outcomes in severe COVID-19 versus placebo.
- Effect
- No Benefit
- Dose
- 300 mg/kg
- Population
- COVID-19 patients
- Participants
- 16
ObservationalImpact of N-acetyl-l-cysteine on SARS-CoV-2 pneumonia and its sequelae: results from a large cohort study2021n=177
An observational study of 177 hospitalized COVID-19 patients found NAC treatment was associated with lower mortality and fewer sequelae.
- Effect
- Benefit
- Population
- Adults
- Participants
- 177
- Avg age
- ~64
ObservationalN-acetyl-cysteine reduces the risk for mechanical ventilation and mortality in patients with COVID-19 pneumonia: a two-center retrospective cohort study2021n=82
An observational study of 82 COVID-19 patients found NAC (600 mg twice daily for 14 days) reduced risk of mechanical ventilation and mortality.
- Effect
- Benefit
- Duration
- 14 days
- Dose
- 600 mg 2×/day
- Population
- COVID-19 patients
- Participants
- 82
Alpha-Lipoic AcidView supplement →
Do not purchase·★★★★★
How we scored this▸
- For people with long-lasting loss of smell after COVID-19, taking 300 mg of alpha-lipoic acid twice daily for 12 weeks does not seem to help improve the sense of smell compared to a placebo.
- Another small study found that taking 800 mg daily for six months, along with smell training, does not improve smell tests or reduce parosmia symptoms compared to smell training alone.
Browse 2 studies
RCTPersistent COVID-19 parosmia and olfactory loss post olfactory training: randomized clinical trial comparing central and peripheral-acting therapeutics2024n=28
6-month RCT in 85 post-COVID olfactory dysfunction patients found umPEALUT plus olfactory training improved smell scores; ALA plus training did not beat training alone.
- Effect
- No Benefit
- Duration
- 6 months
- Population
- Women
- Participants
- 28
RCTAlpha-lipoic acid does not improve olfactory training results in olfactory loss due to COVID-19: a double-blind randomized trial2023n=100
12-week double-blind RCT in 100 post-COVID smell-loss patients found ALA plus olfactory training did not improve smell outcomes beyond training plus placebo.
- Effect
- No Benefit
- Population
- Adults
- Participants
- 100
Milk ThistleView supplement →
Do not purchase·★★★★★
How we scored this▸
- It is not clear if milk thistle helps with COVID-19.
- A small study in hospitalized patients needing oxygen found that taking a specific milk thistle product three times daily for two weeks did not speed up recovery or improve lung health compared to a placebo.
Browse 1 study
RCTEvaluation of the efficacy of oral nano-silymarin formulation in hospitalized patients with COVID-19: A double-blind placebo-controlled clinical trial2022n=25
An RCT of 50 hospitalized COVID-19 patients found nano-silymarin for 2 weeks did not shorten symptom resolution or hospitalization but significantly lowered ALT vs placebo.
- Effect
- No Benefit
- Duration
- 2 weeks
- Dose
- 70 mg/day
- Population
- COVID-19 patients
- Participants
- 25
ResveratrolView supplement →
Do not purchase·★★★★★
How we scored this▸
- A small study tested taking resveratrol four times a day for one to two weeks in people with COVID-19, along with a single dose of vitamin D3.
- The results showed resveratrol did not lower hospital visits, emergency room visits, or lung infection compared to a placebo.
- The study might have been too small to tell if the intervention treatment really works.
Browse 1 study
RCTRandomized double-blind placebo-controlled proof-of-concept trial of resveratrol for outpatient treatment of mild coronavirus disease (COVID-19)2022n=105
In 100 COVID-19 outpatients, resveratrol plus vitamin D3 did not significantly reduce hospitalization, ER visits, or pneumonia versus placebo over 21 days.
- Effect
- No Benefit
- Duration
- 15 days
- Population
- Patients with mild COVID-19
- Participants
- 105
- Avg age
- ~56
RhodiolaView supplement →
Do not purchase·★★★★★
How we scored this▸
- Rhodiola extract alone has not been studied for COVID-19 or long COVID symptoms.
- In a small study, people who had recovered from COVID-19 but still had symptoms took a combination supplement containing rhodiola, schisandra, and eleuthero twice daily for two weeks.
- This helped them walk longer (about 13 minutes more) compared to those who took a placebo, but it did not reduce symptoms like cough, fatigue, headache, or other breathing problems.
- It is not clear how much rhodiola helped in this combination.
Browse 1 study
RCTEfficacy of Adaptogens in Patients with Long COVID-19: A Randomized, Quadruple-Blind, Placebo-Controlled Trial2022n=105
In a prospective study, prophylactic S. boulardii did not significantly lower C. difficile infection rates versus usual care in hospitalized patients.
- Effect
- No Benefit
- Duration
- 2 weeks
- Population
- Patients with Long COVID-19
- Participants
- 105
Evidence visualised
Same ratings as above, aggregated so you can see coverage and imbalance.
| Supplement | DEX | Studies | Meta-analyses | Share |
|---|---|---|---|---|
| Vitamin C | ★★★★★44% | 15 | 2 | 21% |
| Vitamin D | ★★★★★68% | 13 | 12 | 18% |
| Melatonin | ★★★★★52% | 6 | 1 | 8% |
| N-Acetyl Cysteine (NAC) | ★★★★★40% | 5 | 1 | 7% |
| Quercetin | ★★★★★52% | 5 | 1 | 7% |
| Ginger | ★★★★★48% | 4 | 0 | 6% |
| Multivitamin | ★★★★★40% | 4 | 1 | 6% |
| Ashwagandha | ★★★★★48% | 3 | 0 | 4% |
| Echinacea | ★★★★★48% | 3 | 0 | 4% |
| Zinc | ★★★★★68% | 3 | 2 | 4% |
| Alpha-Lipoic Acid | ★★★★★32% | 2 | 0 | 3% |
| Coconut Oil | ★★★★★40% | 2 | 0 | 3% |
| L-Carnitine | ★★★★★44% | 2 | 0 | 3% |
| Milk Thistle | ★★★★★32% | 1 | 0 | 1% |
| Resveratrol | ★★★★★32% | 1 | 0 | 1% |
| Rhodiola | ★★★★★32% | 1 | 0 | 1% |
| Vitamin K | ★★★★★48% | 1 | 1 | 1% |