Hypothyroidism is a frequently diagnosed and simply treated disease. If not recognised, however, in time it may develop into the most severe manifestation of hypothyroidism known as myxedema coma. The term "myxedema coma" is generally seen as misleading since most patients do not initially present in a coma. The typical progression is lethargy evolving into stupor and, eventually, into coma with respiratory failure and hypothermia. It mainly affects elderly women, often occurring in winter and is relatively rare. It can be considered a form of decompensated hypothyroidism often triggered by a variety of non-thyroid conditions or diseases provoking an extremely severe condition of multiple system failure with lethal consequences unless an early diagnosis is made and an aggressive treatment is administered.