Multiple sclerosis is a chronic inflammatory disease of the central nervous system, characterised mainly as an autoimmune neurodegenerative disorder. Its cause is unknown but multifactorial; however, some studies suggest that oxidative stress may be one of the sources, or a consequence of the disease, from loss of oxidant/antioxidant balance. This review studies glutathione, one of the most important agents of the endogenous antioxidant defence system, protecting cells from damage caused by oxidative stress. It evaluates glutathione and the enzymes glutathione peroxidase and glutathione reductase in various forms and stages of the disease. Analysis of a literature search suggests that the scientific community is not unanimous in its views, so more studies are required of patients with different forms of the disease and its manifestations, taking into account that the body functions as a whole and reacts in a compensatory manner. It would seem imperative to achieve a consensus on the pathogenesis responsible for severe disability, and explore sensitive biomarkers of its progression and indicators of oxidative stress. It is also important to promote the development of new therapies, with more studies on other substances such as acrolein, lipoic acid and dimethyl fumarate. Clarification of the mechanisms involved in oxidative stress, in different forms of multiple sclerosis, could result in improvements in the monitoring and prognosis of the disease, with subsequent increases in a patient's quality of life.