Home Ingredients Methylene Blue (Methylthioninium Chloride)
Cognitive

Methylene Blue (Methylthioninium Chloride)

Evidence Level
Limited
2 Clinical Trials
6 Documented Benefits
2/5 Evidence Score

Methylene blue is a synthetic phenothiazine dye first synthesized in 1876 — used as histological stain (1880s) and as prescription medication for methemoglobinemia, urinary tract infections (historical), and ifosfamide-induced encephalopathy. Recently popularized as 'biohacking' supplement for cognition, mitochondrial function, and longevity. Critical cautions: drug-like compound with significant interactions (serotonin syndrome with SSRIs/MAOIs); can cause severe tissue staining; pharmaceutical-grade vs aquarium-grade purity differences are LIFE-THREATENING; G6PD deficiency contraindication.

Studied Dose Pharmaceutical (methemoglobinemia): 1-2 mg/kg IV; 'biohacking' use: 0.5-4 mg/day oral (highly contested); CRITICAL: only PHARMACEUTICAL-GRADE / USP-GRADE methylene blue is appropriate for human consumption
Active Compound Methylene blue (methylthioninium chloride; basic blue 9; CI 52015)

Benefits

Methemoglobinemia Treatment (Established Pharmaceutical Use)

FDA-approved emergency treatment for acquired methemoglobinemia (oxidized hemoglobin can't carry oxygen). 1-2 mg/kg IV reduces methemoglobin to functional hemoglobin. Foundational legitimate medical use.

Supported by Trial 1

Ifosfamide-Induced Encephalopathy

Used to reverse encephalopathy caused by chemotherapy ifosfamide. Specific oncology indication.

Mitochondrial Function Support (Theoretical / Animal Models)

Animal studies show methylene blue supports mitochondrial electron transport chain — donates electrons to complex IV (cytochrome c oxidase). Theoretical 'mitochondrial nootropic' mechanism. Human clinical translation incomplete.

Supported by Trial 1, Trial 2

Cognitive Function (Limited Human Evidence)

trial of low-dose methylene blue (280 mg/kg) showed enhanced memory consolidation in healthy adults via fMRI. Limited rigorous trials. Most claims based on animal studies and theoretical mechanism.

Supported by Trial 1

Alzheimer's Research (Failed Trials)

TauRx Therapeutics tested methylene blue derivative LMTM (LMTX®) in Phase 3 Alzheimer's trials — failed to show benefit. Continues research interest. Original methylene blue not specifically approved for AD.

Supported by Trial 2, Trial 1

Antimalarial / Antimicrobial (Historical and Limited Modern)

Used historically for malaria; antimicrobial activity. Modern use limited to specific contexts.

Supported by Trial 1

Mechanism of action

1

Methemoglobin Reduction

Methylene blue is reduced to leukomethylene blue by NADPH-methemoglobin reductase; leukomethylene blue then reduces methemoglobin (Fe3+) back to hemoglobin (Fe2+). Foundational pharmaceutical mechanism.

2

Mitochondrial Electron Transport Chain Donation

At low doses, methylene blue can act as electron carrier between NADH and cytochrome c oxidase (complex IV) in mitochondrial ETC. Theoretical bypass of electron transport bottlenecks in stressed mitochondria. Basis for nootropic claims.

3

MAO Inhibition

Methylene blue is a potent MAO-A inhibitor — significant clinical implication for serotonin syndrome risk with serotonergic medications. Not a typical 'side effect' but core pharmacology.

4

Nitric Oxide Synthase Inhibition

Inhibits NO synthase — modulates NO/cGMP signaling. Multiple downstream effects.

5

Tau Aggregation Inhibition (Alzheimer's Mechanism)

Inhibits tau protein aggregation — basis for Alzheimer's research direction (LMTX® failed in clinical trials).

Clinical trials

1
Methylene Blue for Memory

Clinical trial of single dose methylene blue (280 mg/kg) vs placebo on memory tasks with fMRI in 26 healthy adults.

26 healthy adults.

Improved memory retrieval and increased fMRI activity in memory-related brain areas. Single dose; small sample; generated continued research interest.

2
LMTM (Methylene Blue Derivative) for Alzheimer's

Phase 3 clinical trial of LMTM (200 mg/day) vs placebo monotherapy or as add-on in Alzheimer's patients.

Alzheimer's patients.

Failed to show benefit on primary outcomes. Significant disappointment for tau-targeting Alzheimer's strategy. Generated questions about methylene blue derivatives' clinical utility.

Side effects and drug interactions

Common Potential side effects

Blue/green urine — universal (harmless but striking).
Tissue staining (skin, mucous membranes, surgical fields).
GI distress (nausea, vomiting).
Headache, dizziness.
Hypertension at higher doses.
Serotonin syndrome with serotonergic medications — potentially fatal.
Hemolytic anemia in G6PD deficiency.
Methemoglobinemia paradoxically at high doses.
Confusion, anxiety.
Skin rash.

Important Drug interactions

Serotonergic medications — potentially fatal serotonin syndrome:
SSRIs (fluoxetine, sertraline, paroxetine, citalopram, escitalopram, fluvoxamine).
SNRIs (venlafaxine, duloxetine, desvenlafaxine).
TCAs (amitriptyline, nortriptyline, imipramine).
MAOIs (selegiline, rasagiline, phenelzine, tranylcypromine, isocarboxazid).
Triptans (sumatriptan, rizatriptan, etc.).
Tramadol, MEPERIDINE, FENTANYL.
ST. John'S Wort.
Lithium, buspirone, TRAZODONE.
MDMA, cocaine.
These combinations require washout periods (typically 5-6 weeks for fluoxetine, 2 weeks for most SSRIs).
G6PD deficiency — contraindicated.
Pregnancy — avoid (multiple concerns).
Lactation — avoid.
Anesthesia — significant interactions; disclose use to anesthesiologist.

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Frequently asked questions about Methylene Blue (Methylthioninium Chloride)

What is methylene blue?

Methylene blue is a synthetic compound with a long medical history (including as a dye and a treatment for a specific blood condition). At low doses it is used as a nootropic and antioxidant for mitochondrial and brain support, and it is being studied for cognition.

What is methylene blue used for?

At low nootropic doses it is explored for cellular energy (mitochondrial support), memory, and mood, owing to its electron-carrying and antioxidant properties. Higher doses are a medical treatment given by professionals.

How much methylene blue is used?

Nootropic use involves very low doses (often a fraction of a milligram per kilogram), and pharmaceutical-grade (not dye-grade) material is essential. Because dosing precision and purity matter greatly, caution is critical.

Is methylene blue safe?

At low, pharmaceutical-grade doses it is generally tolerated (it harmlessly turns urine blue-green), but it is a potent compound. It can interact dangerously with serotonergic drugs (causing serotonin toxicity), so it must not be combined with antidepressants. Only use pharmaceutical-grade product and consult a doctor.

What is the recommended dosage of Methylene Blue?

The clinically studied dose is Pharmaceutical (methemoglobinemia): 1-2 mg/kg IV; 'biohacking' use: 0.5-4 mg/day oral (highly contested); Critical: only Pharmaceutical-GRADE / USP-GRADE methylene blue is appropriate for human consumption Always follow the product label and check with a healthcare provider for personal advice.

Is Methylene Blue safe, and does it have side effects?

For most healthy adults, Methylene Blue is well tolerated at studied doses. Reported effects can include: Blue/green urine — universal (harmless but striking). Tissue staining (skin, mucous membranes, surgical fields). It may also interact with some medications. Methylene Blue is not right for everyone, so check with a healthcare provider first if you are pregnant or breastfeeding, have a medical condition, or take prescription medication.

Does Methylene Blue interact with any medications?

Possible interactions include: Serotonergic medications — potentially fatal serotonin syndrome: SSRIs (fluoxetine, sertraline, paroxetine, citalopram, escitalopram, fluvoxamine). If you take prescription medication, check with a pharmacist or doctor before using it.

How strong is the scientific evidence for Methylene Blue?

NutraSmarts rates the evidence for Methylene Blue as Limited (2 out of 5). It is backed by 2 clinical trials and 3 cited references summarized on this page. A higher rating reflects more, larger, and better-designed human studies.

References(3 citations)

Evidence ratings on NutraSmarts are based on the totality of human clinical research, with emphasis on randomized controlled trials, meta-analyses, and systematic reviews. The references below directly support claims made throughout this page.

  1. Richards A, Marshall H, McQuary A Evaluation of methylene blue, thiamine, and/or albumin in the prevention of ifosfamide-related neurotoxicity. Journal of Oncology Pharmacy Practice. 2011;17(4):372-80. doi: 10.1177/1078155210385159.PubMedUsed to support: Retrospective clinical study evaluating methylene blue in preventing ifosfamide-induced neurotoxicity; found MB prophylaxis reduced incidence of encephalopathy episodes. Supports Ifosfamide-Induced Encephalopathy benefit.
  2. Chain G, Kalia M, Kestenbaum K, Pappas L, Sechser-Perl A, Campino GA, Zaghloul N A novel case of prolonged Ifosfamide encephalopathy and long-term treatment with methylene blue: a case report and review of literature. BMC Pediatrics. 2022;22(1):76. doi: 10.1186/s12887-022-03123-4.PubMedUsed to support: Case report with literature review documenting methylene blue's established use for treating prolonged ifosfamide-induced encephalopathy, including mechanism (reversal of chloroacetaldehyde mitochondrial inhibition). Supports Ifosfamide-Induced Encephalopathy and Mitochondrial Function Support benefits.
  3. Hashmi MU, Ahmed R, Mahmoud S, Ahmed K, Bushra NM, Ahmed A, Elwadie B, Madni A, Saad AB, Abdelrahman N Exploring Methylene Blue and Its Derivatives in Alzheimer's Treatment: A Comprehensive Review of Randomized Control Trials. Cureus. 2023;15(10):e46732. doi: 10.7759/cureus.46732.PubMedUsed to support: Review of RCTs of methylene blue/hydromethylthionine in Alzheimer's disease; finds that large Phase III trials (LUCIDITY, TRx0237) failed primary endpoints, providing honest context that Alzheimer's application remains unproven despite early promise. Supports Alzheimer's Research (Failed Trials) and contextualizes Cognitive Function (Limited Human Evidence) benefits.