The U.S. Centers for Disease Control and Prevention recommends getting vaccinated or taking preventative measures like wearing a face mask to minimize the chances of contracting the coronavirus. But unproven, at-home products remain popular for many.
For example, an Aug. 25 Facebook post with more than 25,000 shares features a list of what it calls “over the counter vitamins for Covid,” including vitamin C, vitamin D, melatonin, zinc, aspirin and quercetin.
“At home vitamin regimen,” reads the post’s caption. “This is not a political post.” Health organizations and experts say there is little evidence these products are effective at treating or preventing COVID-19.
The Facebook user who shared the post did not return a request for comment. Several studies have looked at whether vitamins C and D can help prevent or treat COVID-19. But experts say more research is needed to determine if the supplements are beneficial.
Dr. William Schaffner, medical director for the National Foundation for Infectious Diseases, previously told USA TODAY there’s no convincing evidence vitamins C and D can prevent or treat COVID-19.
He studied 240 hospitalized patients with moderate to severe COVID-19 cases and found that a single oral dose of vitamin D did not significantly reduce the length of hospital stay compared to participants who were given a placebo.
Harvard Medical School says vitamin D may provide protection against COVID-19 because it increases natural defense against viruses and prevents an exaggerated inflammatory response. However, “a specific antiviral effect remains unproven,” the school says on its website.
Similarly, experts at Cochrane, an international organization that reviews medical research, found “the evidence for the effectiveness of vitamin D supplementation for the treatment of COVID-19 is very uncertain.”
The evidence supporting the use of vitamin C is even shakier.
Harvard Medical School warns there is no evidence taking vitamin C will prevent COVID-19. While standard doses are “generally harmless,” high doses can cause nausea, cramps and an increased risk of kidney stones, according to the school.
The National Institutes of Health’s COVID-19 Treatment Guidelines panel says there is insufficient evidence to recommend for or against the use of vitamin C in COVID-19 patients. Likewise, the Mayo Clinic says vitamin C is “unlikely to affect your immune function or prevent you from getting sick.”
The NIH says there is insufficient evidence supporting the use of zinc to treat or prevent the virus and “recommends against using zinc supplementation above the recommended dietary allowance.”
A small clinical trial that used high doses of zinc and vitamin C in non-hospitalized COVID-19 patients ended early because it failed to show any benefits, USA TODAY reported in March.
A study published in the Journal of the American Medical Association found no evidence that zinc alone, or combined with other supplements, would decrease COVID-19 symptoms compared to standard care.
Fewer studies have looked at the effect of melatonin, a supplement used to treat insomnia.
A Cleveland Clinic study found melatonin reduced the chances of a positive COVID-19 test. But the study was observational, and it did not prove the supplement had any benefits for treating COVID-19.