Methylene blue

A synthetic basic dye.

Phase of research

Potential treatment - pre-clinical evidence

How it helps


Drug status

Used to treat other disease

Supporting references
Contradictory references
Clinical trials

General information

Methylene blue is a synthetic basic dye used e.g. in oncologic surgery. It is used as a drug to convert methaemoglobin to haemoglobin (NCIt).

Methylene blue on DrugBank
Methylene blue on PubChem
Methylene blue on Wikipedia


Methylthioninium chloride; Swiss Blue

Marketed as


Structure not available


Supporting references

Link Tested on Impact factor Notes Publication date DB entry date
Methylene Blue Inhibits the SARS-CoV-2 Spike–ACE2 Protein-Protein Interaction–a Mechanism that can Contribute to its Antiviral Activity Against COVID-19
Spike protein ACE2 Small molecule In vitro
in vitro binding assay; hACE-expressing HEK293T cells; SARS-CoV-2 Spike pseudovirus 4.23

Inhibits the interaction between SARS-CoV-2 Spike and the host’s ACE2 receptor in vitro in a dose-dependent manner with IC50 of 3 μM. It also blocks the cell entry of a SARS-CoV-2 Spike pseudovirus with IC50 of 3.5 μM. These concentrations are achievable in blood after oral administration of the drug, as proved by other studies.

Jan/13/2021 Feb/04/2021
Methylene blue inhibits replication of SARS-CoV-2 in vitro
Small molecule In vitro
Vero E6 cells; SARS-CoV-2 strain IHUMI-3 4.62

Inhibited SARS-CoV-2 infection in Vero E6 cells with sub-micromolar EC50 and selectivity index of more than 333. The concentration achievable in human plasma was more than 10-times higher than EC50. The compound is superior to both hydroxychloroquine and azithromycin in these parameters.

Oct/16/2020 Jan/03/2021

Clinical trials

ID Title Status Phase Start date Completion date
NCT05003492 Utilizing the Crosstalk Among Aerosolized Phenformin , Methylene Blue, Photodynamic Therapy , Zinc and Potassium for Treating Severe COVID-19 Infection and Its Inflammatory Complication Not yet recruiting Phase 1|Phase 2 Sep/01/2021 Nov/01/2021
NCT05004805 COVID-19 Methylene Blue Antiviral Treatment Completed Phase 2 Aug/06/2021 Dec/12/2021
NCT04635605 Methylene Blue Treatment of COVID-19 Recruiting Phase 2 Nov/05/2020 Dec/31/2022
NCT04619290 Outpatient Treatment With CoVid-19 With Prexablu Recruiting Phase 1 Oct/12/2020 Dec/30/2020
NCT04376788 Exchange Transfusion Versus Plasma From Convalescent Patients With Methylene Blue in Patients With COVID-19 Recruiting Phase 2 May/20/2020 Sep/01/2020
NCT04547127 A Study to Evaluate Safety and Efficacy of Convalescent Methylene Blue Treated (MBT) Plasma From Donors Recovered From Coronavirus Disease 2019 (COVID-19) Completed Phase 2 Apr/29/2020 Feb/04/2021
NCT04933864 COVID-19 Treatment Using Methylene Blue and Photodynamic Therapy Completed Phase 1 Apr/24/2020 Jul/30/2020
NCT04370288 Clinical Application of Methylene Blue for Treatment of Covid-19 Patients Recruiting Phase 1 Apr/19/2020 Sep/21/2020