The use of complementary and alternative medicine for the treatment of gastrointestinal symptoms in Long COVID: a systematic review

Background: Most people with coronavirus disease 2019 (COVID-19) experience resolution of symptoms within days to weeks following initial infection. In a subset of individuals, symptoms persist longer than 4 weeks, known as ‘Long COVID’. Many gastrointestinal (GI) symptoms persist as part of this syndrome; yet, an approach to treatment remains unclear. Prior studies have demonstrated the efficacy of complementary and alternative medicine (CAM) for the treatment of acute COVID-19 infections, but little data exist regarding the potential use of CAM in the treatment of Long COVID. Objectives: Identify CAM approaches useful in treating the GI symptoms of Long COVID. Design: A systematic review of studies reporting on the use of CAM for the treatment of GI symptoms of Long COVID was performed. Data Sources and Methods: Five electronic databases were searched from January 2019 to November 2022. Studies describing the use of CAM to treat GI symptoms of Long COVID were included and assessed by two independent reviewers. Studies not reporting on GI symptoms or using CAM were excluded. Studies chosen for final review underwent quality and bias assessment using predetermined criteria. The extracted data were synthesized utilizing a framework derived from the National Center of Complementary and Integrative Health categories. Results: The initial search yielded 396 articles. After applying the eligibility criteria, a total of four studies (three case reports and one case series) were included for final review. Two studies used nutritional supplements and two studies used traditional Chinese medicine. Reductions in nausea, loss of appetite, diarrhea, acid reflux, epigastric pain, and bloating were reported. Conclusion: This is the first systematic review to explore the role of CAM in treating GI manifestations of Long COVID. The review identified four studies, all reporting reductions in the GI symptoms of Long COVID. Despite the positive studies included in this review, the overall search yielded few results, all of which were non-experimental. As the post-infectious sequelae of COVID-19 become better recognized in the wake of the pandemic, higher-quality clinical studies are needed.