The consumption of marijuana extracted from Cannabis sativa and indica plants involves an important cultural impact in Mexico. Their psychological stimulatory effect is widely recognized; their biochemical and molecular components interact with CB1 and CB2 (endocannabinoid system) receptors in various central nervous system structures (CNS) and immune cells. The psychoactive element Δ-9-tetrahydrocannabinol (THC) can be reproduced synthetically. Systematic reviews show evidence of therapeutic effectiveness of therapeutic marijuana only for certain symptoms of multiple sclerosis (spasticity, spasms and pain), despite attempts for its widespread use, including refractory childhood epilepsy. Evidence indicates significant adverse effects of smoked marijuana on the structure, functioning and brain connectivity. Cannabis exposure during pregnancy affects fetal brain development, potentially leading to later behavioral problems in children. Neuropsychological tests and advanced imaging techniques show involvement in the learning process in adolescents with substance use. Also, marijuana increases the cognitive impairment in patients with multiple sclerosis. Social and ethical consequences to legally free marijuana for recreational use may be deleterious transcendentally. The medicinal or psychoactive cannabinol no addictive effect requires controlled proven efficacy and safety before regulatory approval studies.