Sepsis and septic shock are public health problems worldwide that represents an excessive cost for health systems. Despite the great technological and research advances, mortality can reach up to 80% in patients with multiple organ failure (FOM). Therapeutic studies focused on evaluating the usefulness of the use of antioxidants have shown different outcomes and results. This randomized clinical trial in patients with septic shock at two general intensive care units try to evaluate the usefulness of four different antioxidant therapies added to the conventional treatment, which includes: n-acetyl cysteine, vitamin C, vitamin E and melatonin. Measurement of parameters before and after treatment of oxidative stress includes nitrates and nitrites, lipid peroxidation, glutathione peroxidase, glutathione s transferase, extracellular activity of SOD, GSH concentration and evaluation of total antioxidant capacity. The investigators will also evaluate the clinical impact of antioxidant therapy with the SOFA score.

Inclusion Criteria:

• Diagnosis of septic shock in the last 24 hours characterized by refractory hypotension and vasopressor requirement despite sufficient fluid resuscitation (20 mL/kg of colloids or 40 mL/kg of crystalloids) to maintain a blood pressure ≥ 65 mmHg with a lactate> 2 mmol/L.
• Admitted to the ICU of the ABC Medical Center.
• Give informed consent.

Exclusion Criteria:

• Patients who refuse to be included.
• Chronic or recent use of steroids.
• Use of statins.
• Patients receiving some type of antioxidant treatment.
• Any contraindication to the use of vitamin C, vitamin E, n-acetylcysteine or melatonin.
• Pregnant women.