Hamadan University of Medical Sciences Avicenna Journal of Pharmaceutical Research 2717-1884 4 2 2025 09 15 The effect of Methylene blue on COVID-19 patients treatment; a double-blind placebo-controlled clinical trial study 87 91 10.34172/ajpr.1103 EN Javad Saffari-Chaleshtori https://orcid.org/0000-0001-9739-5907 Masoud Hafizi https://orcid.org/0000-0001-8003-9041 Ali Baradaran https://orcid.org/0000-0003-4992-1989 Keyhan Ghatreh-Samani https://orcid.org/0000-0001-8993-0527 Roohollah Mohseni https://orcid.org/0000-0001-9759-0876 Akbar Soleimani https://orcid.org/0000-0002-0763-6285 Journal Article 10.34172/ajpr.1103 2024 10 12 2025 01 20 Background and Aims: COVID-19 became widespread in 2019 worldwide and affected everyone. Even though it was a disease caused by a new strain of coronavirus with severe symptoms, some drugs could be effective in treating it. It seems that methylene blue, a drug for treating methemoglobinemia, can be a useful COVID-19 treatment. Material and Method: 60 COVID-19 patients with O2-saturation less than 85% and without any underlying disease were chosen. 30 patients were as the placebo control group and 30 patients were as the methylene blue treated group and received 1 mg/kg of methylene blue for 4 days. Some serum parameters were measured before and after 4 days of treatment. Also, the O2-saturation was measured every 12 hours. Then, the results were compared with each other. Results: Methylene blue decreased the serum CRP (C-reactive protein) (p=0.14), LDH (lactate dehydrogenase) (p=0.08), and Cr (Creatinine) (p=0.12) in the COVID-19 patients non-significantly and increased the serum AST (aspartate aminotransferase) (p=0.40) and ALT (alanine aminotransferase) (p=0.36) parameters in comparison with control placebo group. But, it had no significant effect on O2-saturation (p=0.52) in COVID-19 patients. Conclusion: Methylene blue, as a specific drug for treating met-hemoglobinemia, showed no significant effectiveness of on COVID-19 patients. The results of this study were not in line with the other previous studies.