We report the case of a 16 years old female patient, with a pregnancy history of 11.4 weeks by ultrasound and intrauterine fetal death. In a private clinic were prescribed methotrexate 500 mg intramuscular single dose, and vaginal misoprostol. She had a clinical feature of five days of evolution characterized by fever of 39 degrees C, nausea, general attack and vomiting. The initial diagnosis was severe sepsis secondary to septic abortion, oral candidiasis and acute poisoning by methotrexate. After that, she was referred to the Instituto Nacional de Perinatologia, where stayed with fever for four days, and was managed with hydration, antibiotics, folinic acid and alkalizing. Her recovery was gradual. She was discharged after 12 days with significant clinical improvement. The literature review describes that the use of methotrexate for abortion purpose with therapeutic-dose presents a similar adverse effects to those found in our patient, however there are no case reports that describe the use of this drug in macrodosis for the same purpose, and their cytotoxic effects. We present this case because the patient used a macrodosis of this antimetabolite and due to the premature and empirical management with folinic acid, joined with alkalinization of urine, is the ideal treatment and as it is illustrated in our case.