RESUMO
Background and Aims: Osteoarthritis (OA) is one of the most common debilitating diseases among the aging population. Nigella sativa is one potential treatment for OA. Here, we sought to evaluate the efficacy and safety of Nigella sativa for treating patients with OA. Methods: PubMed, Scopus, Embase, and Web of Science were searched up to October 20, 2022. The primary outcome was changes in the pain score after receiving Nigella sativa or control agents based on the results of randomized controlled trials (RCTs). The secondary outcome was set as the frequency of adverse events reported during the follow-up period. Results: Six RCTs involving a total of 370 patients with knee OA were included in the present systematic review. Among the four screened studies, the topical administration of Nigella sativa oil was found to be more effective than the placebo in relieving pain in three trials. Additionally, the oral use of Nigella sativa oil was assessed in two trials, and an improvement in pain score relative to placebo was documented in only one of the studies. Also, the trial that evaluated the effectiveness of Nigella sativa oral capsules did not demonstrate any difference in pain reduction between the intervention and placebo groups. Overall, either topical or oral administration of Nigella sativa was well tolerated, and no serious adverse events were reported. Conclusion: Nigella sativa is generally safe, but conflicting findings from low-quality studies hinder the ability to make clinical recommendations for or against treating OA. Robust trials are needed for informed decisions.