key: cord-0753407-t9plq975
authors: Hemilä, Harri; Chalker, Elizabeth
title: Vitamin C and zinc lozenges for COVID-19?
date: 2021-05-29
journal: J Am Pharm Assoc (2003)
DOI: 10.1016/j.japh.2021.05.018
sha: 51a16e0d024c8b2fbf186b0f1d44b1d075611685
doc_id: 753407
cord_uid: t9plq975

nan

We share Kathryn Marwitz' concerns regarding widespread misinformation about COVID-19 treatments [1] . However, we do not agree with the statement that "Past examples of vitamin C and zinc, marketed for common cold symptoms, make extensive claims about treating and curing common colds, but the data do not fully support safety and efficacy of these agents. [2] [3] [4] Ironically, these agents are being promoted as unsubstantiated treatments or preventives for COVID-19 today. [2] ".

In our Cochrane review we found that regular vitamin C supplementation of ≥0.2 g/day shortened viral respiratory tract infections in adults by 7.7% (P=0.00018) and in children by 14.2% (P=0.000053) [4] .

Our review supports the safety and efficacy of vitamin C [4] . We did not demonstrate an effect when vitamin C was administered as a treatment, but low doses, short treatment and late treatment may explain negative findings [4] . Vitamin C may also have an effect on COVID-19 [5] , and a recent randomized trial observed that vitamin C increased the recovery rate of SARS-CoV-2 outpatients by 70% [6] .

Marwitz refers to a zinc review [3] , however the review is flawed [7] . There is strong evidence that appropriately composed zinc lozenges can shorten respiratory virus infections [8] [9] [10] . Unfortunately, many of the zinc lozenges on the US market contain either doses of zinc which are too low, or substances that bind zinc ions so tightly that they are ineffective [11] .

There is much misinformation about vitamin C and zinc in popular forums, and also unfortunately in scientific forums [4, 7, [12] [13] [14] [15] , however, the positive findings from randomized trials should not be ignored.

J o u r n a l P r e -p r o o f

The pharmacist's active role in combating COVID-19 medication misinformation

Myth busters: dietary supplements and COVID-19

Zinc for the treatment of the common cold: a systematic review and meta-analysis of randomized controlled trials

Vitamin C for preventing and treating the common cold

Vitamin C and COVID-19

Vitamin 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 trial

Zinc acetate lozenges may shorten common cold duration by up to 40% [eLetter

The effectiveness of high dose zinc acetate lozenges on various common cold symptoms: a meta-analysis

Zinc acetate lozenges may improve the recovery rate of common cold patients: an individual patient data meta-analysis. Open Forum Infect Dis

Zinc lozenges and the common cold: a meta-analysis comparing zinc acetate and zinc gluconate, and the role of zinc dosage

Zinc lozenges as cure for the common cold--a review and hypothesis

Vitamin C supplementation and common cold symptoms: problems with inaccurate reviews

Vitamin C, the placebo effect, and the common cold: a case study of how preconceptions influence the analysis of results

Meta-analysis on vitamin C and the common cold in children may be misleading

Commentary: the long history of vitamin C: from prevention of the common cold to potential aid in the treatment of COVID-19