Evaluating the Role of Vitamin C and Zinc in Treating COVID-19


By Marilyn Bulloch, PharmD, BCPS, FCCP; Fuller Currie, PharmD Candidate 2021; Allison Field PharmD Candidate 2021; and Pierce Gowan PharmD Candidate 2021

Multiple OTC products have been proposed to treat coronavirus 2019 (COVID-19), but their true role remains unclear. Vitamin C and zinc are among the adjuvant treatments being evaluated for patients with COVID-19 due to their various immune-enhancing properties and possible antiviral effects.

Vitamin C, at doses higher than usually seen in outpatient care, has been shown to improve mortality in sepsis and to have positive clinical results in patients suffering from viral infections.1,2 The exact mechanism of vitamin C’s beneficial effects is unclear; however, it is known that vitamin C is a potent antioxidant with immunomodulatory properties and significantly concentrates in important immune cells.1

Studies have shown possible clinical benefits in patients with other viruses, including herpes zoster, varicella zoster, and influenza through an unclear antiviral mechanism.1 It is proposed this may occur with coronaviruses as well.

Zinc is naturally found in the body and is the second-most abundant trace element.3 It has been taken OTC for years to relieve symptoms of viruses such as the common cold or influenza. Unlike vitamin C, zinc’s antiviral mechanism is more established. It inhibits RNA-dependent RNA polymerase necessary for viral replication, including viruses such as influenza and COVID-19.3

Although further studies are needed to establish a firm recommendation regarding the use of vitamin C and zinc in the treatment of COVID-19 positive patients, their past success in other viruses and sepsis, ease of access, relatively low price, and strong safety profiles makes them attractive choices as adjuvant therapies.

The data available are primarily limited to hospitalized patients. Whether they will be beneficial in outpatients with less severe disease also remains to be determined. As with so many other aspects of COVID-19, it is important for pharmacists to be aware of the ongoing studies and adapt accordingly as more robust information becomes available.

A version of this article was originally published by Pharmacy Times. Visit https://www.pharmacytimes.com/news/evaluating-the-efficacy-of-adjunctive-therapies-used-to-treat-covid-19-the-role-of--vitamin-c-and-zinc to view the full article.


  1. Colunga Biancatelli RML, Berrill M, Marik PE. The antiviral properties of vitamin C. Expert Rev Anti Infect Ther. 2020 Feb;18(2):99-101. doi: 10.1080/14787210.2020.1706483. Epub 2019 Dec 23.
  2. Marik PE. Hydrocortisone, Ascorbic Acid and Thiamine (HAT Therapy) for the Treatment of Sepsis. Focus on Ascorbic Acid. Nutrients. 2018 Nov 14;10(11):1762. doi: 10.3390/nu10111762.
  3. Shittu MO, Afolami OI. Improving the efficacy of Chloroquine and Hydroxychloroquine against SARS-CoV-2 may require Zinc additives - A better synergy for future COVID-19 clinical trials. Infez Med. 2020 Ahead of print Jun 1;28(2):192-197.
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