Prevalence of self-medication with vitamin or mineral supplements in the prevention and treatment of COVID-19: a systematic review and meta-analysis.

Background: Self-medication, as a self-care practice, increased dramatically during the COVID-19 pandemic. Among the most prevalent medications used for self-medication were vitamins and minerals. Accordingly, this study aimed to estimate the prevalence of self-medication with vitamins or minerals for preventing and treating COVID-19 and its related factors.

Material and method: A comprehensive search was performed in four electronic databases (PubMed, Web of Science, Scopus, and ProQuest), two preprint repositories (MedRxiv and SciELO), two grey literature sources (Google and Google Scholar), and the reference lists of eligible studies in January 2024. The search strategy was built on two core concepts: "self-medication" and "COVID-19". No language, place, and time restrictions were applied. Risk of bias assessment tool was adapted from Hoy checklist. The protocol of this study was registered under the code CRD42023434567 in the open-access online database of the International Prospective Register of Systematic Reviews (PROSPERO). A random effect model was applied to estimate the pooled prevalence of self-medication. Statistical heterogeneity among the studies was assessed using both the I² statistic and the χ2 test. Moreover, subgroup analysis and meta-regression model were used to identify the potential sources of methodological heterogeneity of the studies. A two‑sided P-value < 0.05 was considered statistically significant.

Results: Out of 1424 non-duplicate studies, 56 were included in the meta-analysis. Vitamin C, vitamin D, B complex, multivitamins, and zinc were most commonly used for self-medication. The pooled prevalence of self-medication with vitamins was 29% (95% CI: 22%,37%; I² = 99.62%), with minerals 15% (95% CI: 8%, 23%; I² = 99.68%), and the corresponding value for the concomitant use of minerals and vitamins was 34% (95% CI: 27%, 42%; I² = 98.72%). The subgroup analysis showed people who lived in the American continent practiced self-medication with vitamins less (Pooled prevalence: 12%, 95% CI: 8%,16%; I² = 91.39%), and self-medication with vitamins and minerals was most prevalent in Asia. Besides; according to I² values, the continents in which the studies were conducted could be the reason for the statistical heterogeneity.

Conclusion: The reported prevalence of self-medication with vitamins and minerals to prevent and treat COVID-19, especially in Asia, is concerning and needs more public health action. In addition, people should be educated about the possibility of poisoning with vitamins and minerals because awareness of the risks of supplements can reduce self-medication practices at present and even in future pandemics.