Are high doses of Vitamin C effective against COVID-19?

In a Nutshell

  • There is no evidence that Vitamin C is protective or preventive against COVID-19
  • High doses of Vitamin C by oral or intravenous route is shown to reduce the duration of illness in critical COVID-19 patients but the data is extremely limited
  • More clinical trials are currently underway to investigate the efficacy of Vitamin C as a viable treatment option in COVID-19 patients

Vitamin C and COVID-19

Vitamin C is widely known for its antioxidant and immune-boosting properties as it wards off free radicals and reactive oxygen species. In addition, it also boosts immunity by other mechanisms such as:

  • Promoting the synthesis of collagen and several other proteins and compounds that helps in immunity
  • Promoting growth of immune cells such as lymphocytes and phagocytes that fights with foreign invaders (such as viruses and bacteria)

Due to devastating effects of COVID-19 infection on individuals, families, communities, and economies worldwide, investigators and healthcare professionals are evaluating all the possible treatment and management options that can prevent, treat, or cure this viral infection. Unfortunately, no vaccine, drug, supplement, or lifestyle modification has yet been found to prevent or treat COVID-19 infection.

Our Verdict

There is no evidence that suggests Vitamin C supplementation can prevent COVID-19 infection.

There is some ongoing investigation that suggests high doses of Vitamin C can improve the outcome in COVID-19 patients by reducing morbidity and mortality. For example:

  • COVID-19 patients report a spike in CRP (C- Reactive Protein) levels in the blood – a key mediator of inflammation and oxidative stress. Vitamin C is known to reduce CRP levels due to inflammation as evidenced by several clinical and research trials.
  • Vitamin C supplementation has been shown to reduce the inflammation among patients of acute lung injury.

There are only handful studies that have investigated the effect of Vitamin C Supplementation on COVID-19 patients. One such study was conducted on 50 critical COVID-19 patients in China who were managed with high doses of Vitamin C (10g-20g/ day) that were administered 8 to 10 hours apart via intravenous route. Investigators reported instant improvement in oxygenation indices of patients and eventually all patients recovered and discharged (2).

Another clinical trial is underway that will be conducted on 140 COVID-19 patients in China, in which investigators will administer Vitamin C via intravenous route in a dose of 24g/day. This trial will be completed by September 2020 and may shed more light on the effectiveness of Vitamin C for COVID-19 treatment (3)


Nuances/ Safety

A dose of 1.5 g/kg body weight is considered safe and optimal for COVID-19 patients as suggested by some investigators (2) however, it is suggested to avoid taking high doses of Vitamin C without consulting a healthcare professional as you may develop side effects such as diarrhea.


Strength of Evidence: C

There is extremely limited data that can suggest Vitamin C can effectively treat or cure COVID-19 infection.


Our Ruling

Vitamin C is a powerful antioxidant that is known to boost your immune system. However, COVID-19 is a serious and life-threatening infection and so far there is limited clinical data that can prove the effectiveness of Vitamin C as a sole management option for the management of COVID-19 infection. It is therefore recommended to practice social distancing, avoid crowded or closed spaces and adopt other preventive measures such as use of sanitizers, and wearing facial masks when you are outdoor.

Our Sources:

  1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7137406/
  2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7167497/
  3. https://ccforum.biomedcentral.com/articles/10.1186/s13054-020-02851-4
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How we grade evidence?

Learn more about it here.