Herbal therapy in opioid withdrawal syndrome: A systematic review of randomized clinical trials

BACKGROUND: Medicinal plants have revealed much attention as an alternative or complementary treatment for opioid withdrawal syndrome. The current review collects all available literature to verify the efficiency of herbal remedies in the management of symptoms associated with opioid withdrawal. METHODS: A systematic literature search was conducted from January 1990 to May 2021 on four bibliographic databases (Scopus, PubMed, Embase, and Web of Science) using the search terms "medicinal plant", "withdrawal syndrome", "opioid", and all their equivalents. All randomized controlled trials (RCTs), published in the English language were included for data synthesis. The search was performed according to the preferred reporting items for systematic reviews and meta-analyses (PRISMA). The Cochrane risk of bias tool was used to verify the quality of the included clinical trials. FINDINGS: A total of 12 RCTs were collected and used for data synthesis. The results of these studies indicated that herbal medicines were effective in treating opioid withdrawal syndrome and could alleviate the withdrawal symptoms, such as abdominal constrictions, diarrhea, bone pain, perspiration, and insomnia, when compared to conventional medications such as buprenorphine, clonidine, and methadone. However, more than 30% of RCTs were found to be at high risk of bias in the areas of selection, performance, detection, attrition, and reporting. CONCLUSION: Although several RCTs have proven that herbal remedies are effective in reducing opioid withdrawal symptoms, the findings need to be viewed more carefully. Further RCTs with more participants, longer duration, and less risk of bias are needed in the claimed cases.