The purpose of this study is to evaluate the efficacy and safety of methylene blue among adult patients with septic shock.

Septic Shock is a leading cause of morbidity and mortality in critically ill patients worldwide.

A potential benefit of methylene blue in the treatment of septic shock has recently been described by Estrada. In patients with septic shock, methylene blue initiated within 24 h reduced time to vasopressor discontinuation and increased vasopressor-free days at 28 days. It also reduced length of stay in ICU and hospital without adverse effects.

In this randomized controlled trial, we aim to evaluate the efficacy and safety of methylene blue on septic shock.

Inclusion Criteria:

1. age 18 years old or older;
2. diagnosis of septic shock within 12 h.

Exclusion Criteria:

1. recent intake (4-weeks) of selective serotonin re-uptake inhibitors;
2. pregnant;
3. definitive pulmonary hypertension or chronic pulmonary heart disease;
4. known glucose-6 phosphate dehydrogenase (G-6PD) deficiency;
5. known allergy to methylene blue, phenothiazines, or food dyes;
6. anticipated death from a preexisting disease within 90 days after randomization (as determined by the enrolling physician);
7. refusal of the attending staff or patient family;
8. participated in other study.