Methods for treating Shiga toxicosis, caused by infection with Shiga toxin bacteria, are provided. The methods include administering to a subject in need thereof an effective amount of one or more active agents selected from tamoxifen, 4-hydroxytamoxifen, endoxifen, toremifene, raloxifene, bazedoxifene, and pharmaceutically acceptable salts thereof. In some embodiments, the methods further include the administration of an antibiotic or a manganese compound to the subject. Pharmaceutical compositions for the treatment of Shiga toxicosis are also described.