Efficacy and Safety of Add-On Plant-Based Drugs for COVID-19 Patients: A Review of the Randomized Control Trials

COVID‐19 caused by the infection of SARS‐CoV‐2 is still a global concern. WHO reported that from 13 March to 9 April 2023, there were 3 million new cases and approximately 23,000 deaths, mostly occurring in the South-East Asia and Eastern Mediterranean regions, which is predicted due to the new Omicron variant, Arcturus XBB.1.16. Many studies have reported the potency of medicinal plants in enhancing the function of the immune system to combat virus infection. The literature review aimed to describe the efficacy and safety of add-on plant-based drugs for COVID-19 patients. The articles were explored on the PubMed and Cochrane Library databases, and published during 2020–2023. Twenty-two varieties of plants were used as add-on therapy for COVID-19 patients. These plants were Andrographis paniculata, Viola odorata, Withania somnifera, Zingiber officinale, Curcuma longa, Ferula foetida, Centella asiatica, Thymus vulgaris, Citrus sinensis, Eugenia caryophyllus, Boswellia carterii, Elettaria cardamomum, Salvia rosmarinus, Piper nigrum, Alstonia scholaris, Picrorhiza kurroa, Swertia chirata, Caesalpinia crista, Cucurbita maxima, Tinospora cordifolia, Ocimum sanctum, and Allium sativum. The best efficacy of an add-on therapy for COVID-19 patients was found in A. paniculata herbs as a single component in pharmaceutical dosage form or in combination with other plants. The safety of the plant has been confirmed. A. paniculata does not show interaction with remdesivir or favipiravir, however, caution and therapy drug monitoring is needed if A. paniculata is used in combination with lopinavir or ritonavir because a strong noncompetitive inhibition of CYP3A4 may occur.