Primary Care in Rochester and Kasson

Using vitamins to combat COVID-19: What's the evidence?

9/17/2020 by Denise Dupras, M.D.


In recent weeks, there've been numerous claims on social media that vitamin supplements are effective for prevention and treatment of COVID-19. But what is the actual evidence that they can help you if you become sick? And what are the risks of using vitamins as a treatment?

Vitamin C

What's being reported: A very high dosage of vitamin C given intravenously has been reported, by researchers in Italy and China, to be helpful in patients hospitalized with COVID-related pneumonia.

The results of these studies have not been formally published for the medical industry's reference, and without published medical trials, we don't know if the results are truly effective or what side effects may be involved. The high doses of vitamin C reported in these stories cannot be met by taking over-the-counter vitamin pills, and if you were to try, you could give yourself kidney stones, nausea, vomiting, diarrhea, dizziness, and interfere with other medications. 

More formal studies of whether vitamin C is helpful in patients with COVID-19 are currently being conducted, and the safest course of action is to check with your primary care provider before adding a vitamin supplement to your diet. 

Vitamin D

What's being reported: There are studies looking at whether low vitamin D levels are related to outcomes in patients with COVID-19 infections. There are no studies looking at actual treatment of COVID-19 with vitamin D.

High-dose vitamin D has potential serious side effects, and, again, you should check with your primary care provider before adding a supplement to your diet. If he or she is concerned about your vitamin D status, a blood test can be used to check for a deficiency. They can also advise you on how much vitamin D you should be getting every day and whether you should consider taking supplements to boost your daily intake. 


What's being reported: One study looked at the addition of zinc to azithromycin and hydroxychloroquine in the treatment of hospitalized patients. 

The results of these studies have not been published for the medical community's review, and the doses used in the study were very high and exceeded those considered generally safe. Zinc should only be used under a doctor's supervision to ensure proper dosages. 

Other substances

Other substances have been suggested — including elderberry, thiamine and melatonin — and remain untested, have potential harms, or have shown no benefit and should not be used. 

Bottom line

The bottom line is that there is no scientific data supporting the use of vitamins C, D, zinc or other vitamin supplements to prevent or treat COVID. Talk to your primary care provider for advice on vitamins and whether you should consider taking supplements to boost your daily intake. 

Dr. Denise Dupras is a general internist in Primary Care in Rochester and Kasson's Division of Community Internal Medicine (CIM). She completed her M.D.-Ph.D. at Mayo Medical School and her residency in Internal Medicine at Mayo Clinic in Rochester. Her interests include medical education and evidence-based medicine.