Turmeric (Curcuma longa Linn), which belongs to the Zingiberaceae family, is one of the most well-known and thoroughly studied medicinal plants, and is also one of the few medicinal plants that have been scientifically proven to be beneficial to human health. The most frequently used part of turmeric is the rhizome, for which several studies have reported to contain high levels of beneficial essential oils and numerous chemical constituents. One of the most well-studied chemical constituents of turmeric is curcumin, which has exhibited the ability to target multiple signaling pathways while also demonstrating certain pharmacological activities at the cellular level in preclinical studies. Advancing these preclinical studies, numerous clinical studies on various diseases involving turmeric-based medication have been conducted, including dyspepsia, irritable bowel syndrome, peptic ulcer, and cancer lesions, among various other diseases. We report an extensive examination of the clinical aspect of turmeric and turmeric-based medication, including its isolates. This review provides a comprehensive overview of the state-of-the-art clinical studies involving turmeric and its effects on various diseases.