Methylene Blue Protocol

Dosing & Research

Last Updated: August 30, 2026

Also known as: Methylthioninium Chloride

Chemical Identity

Amino Acid Sequence: Not applicable (not a peptide; synthetic phenothiazine dye)
Molecular Formula: C16H18ClN3S
Molecular Weight: 319.85 (anhydrous); ~373.9 (trihydrate) g/mol
CAS Number: 61-73-4 (anhydrous); 7220-79-3 (trihydrate)

Mitochondrial electron carrier , Cognitive models , Neuroprotection , FDA-approved for methemoglobinemia (not a peptide)

Evidence Level

Human Clinical Data Available

Species Studied

Human • Rat • Mouse • In vitro

Half-Life

~5–24 hours (plasma; multi-compartmental; longer tissue effects due to redox cycling)

Administration

• Oral
• Intravenous

Frequency

Daily (low-dose Research Protocols)

How It Works

Mitochondrial electron carrier / alternative electron transport (bypasses Complex I/III at low doses)
Redox cycling (methylene blue ↔ leucomethylene blue)
Antioxidant effects and reduced oxidative stress
Potential tau aggregation modulation and neuroprotection models
Memory consolidation / attention signals in limited human data

Dosing Structure

Dose

0.5–2 mg/kg oral

Frequency

Daily (low-dose Research Protocols)

Notes

Hormetic dose-response: low doses act as a mitochondrial electron carrier while high doses can become pro-oxidant. FDA-approved only for acquired methemoglobinemia (IV 1-2 mg/kg). Research interest centers on mitochondrial support, cognition, and neuroprotection. Strongest human cognition signal is limited to single-dose fMRI studies. Alzheimer's derivative (LMTM) Phase 3 trials largely failed primary endpoints. Oral bioavailability is approximately 70% in some data, with peak levels at 1-2 hours. Avoid concurrent serotonergic agents (SSRIs/SNRIs) due to MAO inhibition and serotonin syndrome risk. G6PD deficiency is a hard contraindication due to hemolysis risk. Turns urine and tongue blue-green; this is expected and not a safety signal. Strict cycling data is limited. Storage: protect from light.

Example Protocols

Dose: 0.5–2 mg/kg oral

Frequency: Daily (low-dose Research Protocols)

Duration: Study-dependent

Off Period: Not listed

Calculate dosing →

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Protocol Notes

•

Hormetic dose-response: low doses act as a mitochondrial electron carrier while high doses can become pro-oxidant.

•

FDA-approved only for acquired methemoglobinemia (IV 1-2 mg/kg).

•

Research interest centers on mitochondrial support, cognition, and neuroprotection.

•

Strongest human cognition signal is limited to single-dose fMRI studies.

•

Alzheimer's derivative (LMTM) Phase 3 trials largely failed primary endpoints.

•

Oral bioavailability is approximately 70% in some data, with peak levels at 1-2 hours.

•

Avoid concurrent serotonergic agents (SSRIs/SNRIs) due to MAO inhibition and serotonin syndrome risk.

•

G6PD deficiency is a hard contraindication due to hemolysis risk.

•

Turns urine and tongue blue-green; this is expected and not a safety signal.

•

Strict cycling data is limited.

•

Storage: protect from light.

What Is Methylene Blue?

Methylene blue (methylthioninium chloride) is a synthetic phenothiazine dye first prepared in 1876. It is not a peptide. It is FDA-approved for the treatment of acquired methemoglobinemia. At low doses it acts as a mitochondrial electron carrier, accepting and donating electrons and supporting cellular respiration under stress. Research interest centers on potential cognitive, neuroprotective, and anti-aging effects via mitochondrial and redox mechanisms, though human evidence outside the approved indication remains limited and mixed.

Research Observations - Not Medical Claims

▸Rat memory model: Low-dose methylene blue increased brain cytochrome oxidase activity and restored memory retention in rats with metabolically impaired oxidative capacity (PMID: 14724055).
▸Human fMRI study: A randomized, double-blinded, placebo-controlled trial found low-dose methylene blue increased functional MRI response during short-term memory and attention tasks, with a 7% increase in correct memory-retrieval responses (PMID: 27351678).
▸Alzheimer's derivative failed: A Phase 3 trial of LMTM (a reduced methylthioninium derivative developed as a tau-aggregation inhibitor) did not show benefit as an add-on treatment for mild-to-moderate Alzheimer's disease at either tested dose (PMID: 27863809).
▸Mechanistic review: Methylene blue acts on multiple cellular and molecular targets in the nervous system, including mitochondrial electron transport, nitric oxide/cGMP signaling, and monoamine oxidase inhibition (PMID: 19760660).
▸FDA-approved indication: Methylene blue is the first-line treatment for acquired methemoglobinemia, administered intravenously at 1-2 mg/kg; this remains its only approved use.