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Methylene Blue

Also known as: Methylthioninium chloride, MB, Methylene Blue, Basic Blue 9

1
1 · Natty510 · Enhanced

Lower numbers = closer to natural. Higher numbers = more enhanced.

Why this rating?

Methylene blue is an old FDA-approved drug (for methemoglobinemia) and industrial dye that has become a popular low-dose nootropic / longevity supplement on the basis of its mitochondrial redox (electron-cycling) activity. It is not anabolic, not hormonal, and has no muscle-building or athletic effect, the same tier as other pure-health/cognitive-support compounds (NMN, TUDCA, glutathione) that sit at the bottom of the scale. Rated 1. Its genuine drug-interaction dangers (serotonin syndrome, G6PD hemolysis) are real and disqualifying for some users, but that risk is captured in sideEffectSeverity, not in how far it pushes someone beyond natural muscular potential, which is essentially not at all.

Overview

Methylthioninium chloride, methylene blue, is a phenothiazine-derived dye and medication (a dark green powder that dissolves to a deep blue solution). Medically it is the FDA-approved antidote for methemoglobinemia. It has become a fashionable low-dose nootropic and 'longevity' supplement because it can act as an alternative electron carrier in mitochondria. Its established medical use is solid; its cognitive/anti-aging use is trend-driven and unproven, and it carries genuine interaction risks.

Purpose & Use Cases

Methemoglobinemia (FDA-approved)

The established medical use: IV methylene blue reduces methemoglobin back to normal hemoglobin, restoring oxygen-carrying capacity. Given in hospital, typically for methemoglobin levels above ~30% or symptomatic despite oxygen.

Nootropic / Cognitive (off-label)

Promoted at low oral doses for focus, memory and mood via its mitochondrial electron-cycling action. Human evidence is preliminary; outside the medical indication its effectiveness is unproven.

Longevity / Mitochondrial Support (off-label)

Marketed for anti-aging and metabolic/mitochondrial support. This is a trend, not an established benefit.

Other Medical Uses

Off-label / other established uses include ifosfamide-induced encephalopathy, vasoplegic syndrome (raising blood pressure in refractory shock), and surgical tissue staining.

Benefits

  • FDA-approved, effective antidote for methemoglobinemia
  • Acts as an alternative mitochondrial electron carrier (redox cycler)
  • Promoted for cognition, mood and longevity (evidence preliminary)
  • Non-hormonal: no HPTA effect
  • Established medical uses in ifosfamide encephalopathy and vasoplegic shock

Good to Know

Old drug, new supplement trend

Methylene blue is a genuine FDA-approved medicine for methemoglobinemia (given IV) and an industrial dye. Its low-dose oral use for focus, mood and longevity rides on its mitochondrial electron-cycling action, a real mechanism, but the human cognitive/anti-aging evidence is still preliminary and unproven.

It is an MAO inhibitor, serotonin-syndrome risk

Methylene blue is a potent reversible MAO-A inhibitor. Stacked with SSRIs, SNRIs, other MAOIs, or certain opioids it can cause serotonin syndrome, which can be fatal. If you take a serotonergic antidepressant, methylene blue is not a casual supplement.

Know your G6PD status, and mind the dose

It is contraindicated in G6PD deficiency (causes hemolysis). And dose direction matters: low doses reduce methemoglobin, but high cumulative doses (~7 mg/kg+) paradoxically create it. This is a compound to keep low-dose and pharmaceutical-grade.

Dosage Guidelines

Experience LevelDosage Range
Beginner10 – 20 mg/day
Intermediate20 – 40 mg/day
Advanced40 – 80 mg/day
Frequency
Community nootropic protocol: once daily, oral, typically in the morning on an empty stomach (it can disrupt sleep if taken later). Some cycle it 5 days on / 2 days off to limit tolerance, though there is no clinical data defining an optimal schedule. This oral routine is entirely separate from methemoglobinemia treatment, which is a clinician-administered IV protocol, not a self-directed regimen.
Typical Cycle Length
4 – 12 weeks
Notes

The ranges above are a COMMUNITY-DERIVED, non-clinical protocol (e.g. biohacking dosing guides), not an FDA/RCT-validated regimen, flagged as uncertain. Community guidance centers on roughly 0.5-1.0 mg/kg/day (about 35-85mg for a 70-85kg adult), usually starting at 10-20mg/day, with the effect described as biphasic/hormetic ("higher is not better". Going well past ~1mg/kg is said to flip the redox effect from antioxidant to pro-oxidant). This is a different dosing world from (1) the VERIFIED medical IV dose for methemoglobinemia, 1 mg/kg over 5-30 minutes, repeatable after 1 hour if levels remain elevated (StatPearls), and (2) published human research doses, which run much higher than the community nootropic range: a single 260mg (~4 mg/kg) post-session oral dose improved fear-extinction memory in a 2014 RCT (Telch et al., Am J Psychiatry), and chronic psychiatric-trial dosing has run 15-300mg/day for up to two years (bipolar disorder) and 8-250mg/day in Alzheimer's trials of the related methylthioninium drug TRx0237. None of those higher research/medical doses should be read as endorsing higher community dosing, real toxicity ceilings exist: cumulative doses of ~7 mg/kg or more can themselves cause toxicity/paradoxical methemoglobinemia, and ~20 mg/kg+ can cause severe hemolysis. Use only pharmaceutical/USP-grade product, never industrial dye.

Half-Life

Reported values vary by study: an early IV pharmacokinetic study found a terminal half-life of ~5.25 hours, but a later, more rigorous study measuring both routes found ~18.5 hours IV and ~18.3 hours oral (as an aqueous solution), i.e. IV and oral clearance are actually similar once measured the same way, not IV-fast/oral-slow as the older figure alone implies. Oral bioavailability is much higher as a solution than as a dry-gelatin capsule.

Side Effects

Serotonin Syndrome (with serotonergic drugs)

uncommon
Severity
5/5

Methylene blue is a potent reversible MAO-A inhibitor. Combined with SSRIs, SNRIs, MAOIs, certain opioids or other serotonergic drugs it can precipitate serotonin syndrome, potentially life-threatening, especially at higher doses (>5 mg/kg IV).

Mitigation

Do NOT combine with SSRIs/SNRIs/MAOIs or other serotonergic agents. This is the single most important interaction to respect.

Hemolysis in G6PD Deficiency

uncommon
Severity
5/5

In people with G6PD deficiency, methylene blue can cause hemolytic anemia (and can even worsen methemoglobinemia), because impaired NADPH generation leaves red cells unable to handle the oxidative load.

Mitigation

Contraindicated in G6PD deficiency. Know your G6PD status before any use.

Blue/Green Discoloration

very common
Severity
1/5

Blue or green urine (and sometimes skin/mucosa) is expected. It is a dye. Harmless but startling.

Mitigation

Expected and harmless; resolves as it clears.

High-Dose Methemoglobinemia (paradoxical)

rare
Severity
4/5

At high cumulative doses methylene blue paradoxically induces methemoglobinemia (the opposite of its therapeutic effect), mild at ~7 mg/kg, and serious toxicity at very high doses (~20 mg/kg+).

Mitigation

Stay well below medical dose ceilings; nootropic use should be very low-dose.

GI Upset / Headache

common
Severity
1.5/5

Headache, nausea and vomiting.

Mitigation

Lower the dose; take with food.

General Mitigation Strategies

Two interactions can be dangerous and must be respected: (1) do not combine with serotonergic drugs (SSRIs/SNRIs/MAOIs, some opioids). Methylene blue is an MAO-A inhibitor and can trigger serotonin syndrome; and (2) it is contraindicated in G6PD deficiency (hemolysis). Keep doses low: high cumulative doses paradoxically cause methemoglobinemia. Blue/green urine is expected and harmless. Use only pharmaceutical/USP-grade material.

Post Cycle Therapy (PCT)

✓PCT Not Required

Not hormonal. Does not affect the HPTA. No PCT required.

How It Works

Methylene blue is a redox (reduction-oxidation) cycler. In its reduced form (MBH2) it can directly reduce cytochrome c in the mitochondrial electron transport chain, effectively bypassing complexes I and III, and it accepts electrons from NADH, NADPH and FADH2. This 'alternative electron carrier' behavior is the rationale for its proposed pro-mitochondrial, pro-cognitive effects and limits superoxide formation. Separately, in treating methemoglobinemia it chemically reduces the ferric iron of methemoglobin back to functional ferrous iron. Importantly, it is also a potent, reversible inhibitor of monoamine oxidase A (MAO-A), the basis of its serotonin-syndrome interaction risk.

Fundamentals

Reference on the practices relevant to Methylene Blue: how they are done and where they go wrong. Not a recommendation to use it.

Bloodwork: what to measure and when→

The markers that matter here

Warning signs & when to seek care→

When to stop and get help

WADA Status

✓Not Prohibited by WADA

Methylene blue (methylthioninium) is not named on the WADA Prohibited List and has no stimulant, anabolic, hormonal, or masking-agent action that would place it in a banned category. It is a legitimate medical dye/antidote with no established performance-enhancing effect. As always, athletes should verify current status via Global DRO, since list wording can change year to year.

References

Last updated: July 18, 2026