Cannabis has been widely used as a medicinal plant for millennia; however, studies related to its main components were first conducted in 1960. Subsequently, laboratories have produced new components and structures related to its active biological properties. Countries that have approved the medicinal use of cannabis impose regulations that govern its clinical and scientific use. One means of administering medicinal cannabis is via a magistral preparation that must have a medical prescription and be prepared in an establishment that meets quality standards to ensure the quantities of its main components, such as tetrahydrocannabinol (THC) and cannabidiol (CBD). Furthermore, suppliers must have a clear indication of its use in the patient before prescription. This review shows the published evidence regarding the clinical use of medicinal cannabis magistral preparations in the management of post-chemotherapy nausea and vomiting, neuropathic pain in multiple sclerosis, and anorexia and cachexia in patients with HIV.