Peptide LibraryMethylene Blue
Methylene Blue is a research peptide in the Mitochondrial Electron Carrier class. At therapeutic doses methylene blue is reduced to leucomethylene blue, which donates electrons to methaemoglobin and converts ferric iron back to the ferrous form that can carry oxygen.
For research use only.
Key Facts
- CAS
- —
- Molecular Weight (MW)
- 319.9 g/mol
- Half-life
- —
- FDA status
- Approved
- Evidence level
- FDA Approved
- Human dose established
- Yes
- Administration Route
- Intravenous (approved) · Oral (trials only)
- Frequency
- Single dose, repeatable once after one hour
- Last updated
- Nov 7, 2026
- Reviewed
- Nov 7, 2026
Vendor price snapshot
Each vendor's price is the median price per mg of its own listings; with fewer than 3 vendors there is no typical range. From public vendor listings collected in Nov 2026, so confirm the live price on the vendor site. Peptide Library does not sell peptides.
- Vendors listing this peptide
- 11
- Listed offers
- 12
- Price per mg (peptide vials)
- $2.00/mg
By form
Each form is priced on its own: a price per mg doesn't make a spray or a capsule equivalent to a vial.
- Peptide vials1 vendor · $2.00/mg
- Solutions1 vendor
- Capsules5 vendors · $0.050–$0.052/mg
- Tablets2 vendors · $0.033–$0.044/mg
- Liquids1 vendor · $0.050/mg
Research summary
Phenothiazine dye approved as an intravenous treatment for acquired methaemoglobinaemia. It is separately sold as a research chemical and studied at low doses for mitochondrial and cognitive endpoints, which are not approved uses.
Research evidence
- Regulatory review (FDA label)1 reviewed source
- Controlled human trials2 reviewed sources
- Early or uncontrolled human studiesNone in reviewed sources
- Lab & animal studiesNone in reviewed sources
How it works
Each step shows whether the sources Peptide Library has reviewed include that kind of research. Counts are reviewed sources, not every study ever published. Reviews and programme summaries that describe human use are shown as "reported", not as trials, and registered trials without published results are listed but not counted. A higher step means research has progressed further; it does not mean a compound works better or is safer. Compounds whose evidence has not been reviewed yet show "Not reviewed" instead of a guess.
Peptide Library's Methylene Blue profile summarises 5 cited studies listed in the Science section, the compound's regulatory status, and research-protocol parameters reported for it. It is a research reference, not medical advice.
Methylene Blue dosage evidence
Methylene blue has an FDA-approved human dosage for one use. As ProvayBlue it is given as 1 mg/kg intravenously over 5–30 minutes for acquired methemoglobinemia, with one repeat dose of up to 1 mg/kg after an hour if needed. Oral use has been studied in trials, for example 195 mg a day as an add-on in bipolar disorder, but no oral dose is approved.
| Human dosing established | Yes |
|---|---|
| Studied dose range | 1 mg/kg IV, repeatable once (approved label) |
| Route | Intravenous (approved) · Oral (trials only) |
| Frequency | Single dose, repeatable once after one hour |
| Duration studied | Acute treatment |
| Evidence level | FDA Approved |
| Last reviewed | 2026-11-07 |
Research-reported dosing
Doses as studied, one row per regimen. Different trials used different regimens; they are listed separately rather than averaged.
| Study / context | Population | Dose | Route | Frequency | Duration | Outcome studied | Source |
|---|---|---|---|---|---|---|---|
| FDA label — ProvayBlueFDA-approved label · FDA prescribing information | Pediatric and adult patients with acquired methemoglobinemia | 1 mg/kg; a repeat dose of up to 1 mg/kg may follow one hour after the first if methemoglobin stays above 30% or symptoms persist. A single 1 mg/kg dose in moderate or severe renal impairment. | Intravenous, over 5–30 minutes | Once, repeatable once | Acute | Reduction of methemoglobin | PROVAYBLUE (methylene blue) injection — FDA prescribing information, DailyMed |
| Randomised crossover trial — residual symptoms of bipolar disorder (2017)Clinical trial · Double-blind randomised crossover trial (NCT00214877) | Adults with bipolar disorder taking lamotrigine (n=37) | 195 mg a day (active) versus 15 mg a day (used as the placebo arm) | Oral | Daily | 6-month crossover trial | Depression and anxiety scores improved on the active dose; cognitive measures did not change significantly | Methylene blue treatment for residual symptoms of bipolar disorder: randomised crossover study. Br J Psychiatry. 2017. |
| Neuroimaging crossover study in bipolar disorder (2024)Clinical trial · Single-blind randomised crossover study | Euthymic adults with bipolar I disorder and matched healthy controls (n=30) | 0.5 mg/kg, single infusion | Intravenous | Once | Single session | Change in cerebral blood flow and oxygen metabolism on MRI | Altered oxidative neurometabolic response to methylene blue in bipolar disorder revealed by quantitative neuroimaging. J Affect Disord. 2024. |
Where sources disagree
- The only approved use is intravenous treatment of acquired methemoglobinemia. Low-dose oral protocols published for energy or cognition do not come from the label, and the oral trials above tested specific doses in specific patient groups.
- The label contraindicates methylene blue in G6PD deficiency because of the risk of hemolytic anemia, and carries a boxed warning for serious or fatal serotonin syndrome when combined with serotonergic drugs (such as SSRIs, SNRIs and MAOIs) or opioids.
- Methylene blue is a small-molecule dye, not a peptide. It is listed here because it is widely discussed alongside research peptides.
Sequence & molecular data
| Molecular formula | C16H18ClN3S |
|---|---|
| Molecular weight | 319.9 g/mol |
| PubChem CID | 6099 |
| FDA UNII | 8NAP7826UB |
| ChEMBL | CHEMBL405110 |
| DrugBank | DB09241 |
Identifiers link to the public PubChem, FDA Substance Registration (UNII), ChEMBL and DrugBank records for the same entity.
Science
Mechanism of Action
At therapeutic doses methylene blue is reduced to leucomethylene blue, which donates electrons to methaemoglobin and converts ferric iron back to the ferrous form that can carry oxygen. At much lower concentrations it can act as an alternative electron carrier in the mitochondrial electron transport chain, cycling between oxidised and reduced forms and bypassing complex I/III blockade — the property behind its investigation in neurodegenerative and metabolic models. It is also a monoamine oxidase inhibitor, which is the basis of its serotonin syndrome risk.
Regulatory & research status
Methylene Blue is an FDA-approved product for specific labelled indications. Approval does not extend to the research contexts described on this page, and approved products are prescription medicines.
| FDA status | Approved |
|---|---|
| Research status | Approved product (see FDA status) |
| Availability | Prescription-Only |
| WADA (sport) | Unknown / Not Listed |
| Library classification | FDA-Approved |
How FDA approval, compounding and research-only status differ
Benefits
—
Methylene Blue side effects
No side effects listed yet for this entry.
Storage & stability
This compound is not supplied as a powder to be mixed, so the freeze-dried powder and reconstitution handling described for research peptides does not apply. Storage conditions are product-specific: follow the label or packaging of the product itself.
Methylene Blue: frequently asked questions
What is Methylene Blue?
Phenothiazine dye approved as an intravenous treatment for acquired methaemoglobinaemia. It is separately sold as a research chemical and studied at low doses for mitochondrial and cognitive endpoints, which are not approved uses.
How does Methylene Blue work?
At therapeutic doses methylene blue is reduced to leucomethylene blue, which donates electrons to methaemoglobin and converts ferric iron back to the ferrous form that can carry oxygen. At much lower concentrations it can act as an alternative electron carrier in the mitochondrial electron transport chain, cycling between oxidised and reduced forms and bypassing complex I/III blockade — the property behind its investigation in neurodegenerative and metabolic models.
Is Methylene Blue FDA approved?
Yes. Methylene Blue is approved by the FDA, and approved products are prescription medicines. Approval is always for specific indications studied in clinical trials, so an approved status does not mean the compound is approved for every use it is discussed for. Research-chemical material sold under the same name is not the approved product.
What peptides are similar to Methylene Blue?
Compounds most often compared with Methylene Blue include Elamipretide (SS-31), SS-20, MOTS-C and 5-Amino-1MQ. They are grouped by shared mechanism or research area rather than by equivalence, and their regulatory status and evidence base differ.
References
- Application of methylene blue for the prevention and treatment of COVID-19: A narrative review — Iran J Basic Med Sci, 2024External reference
- Why Methylene Blue Have to Be Always Present in the Stocking of Emergency Antidotes — Curr Drug Targets, 2018External reference
- Methylene Blue for Vasoplegic Syndrome — Heart Surg Forum, 2017External reference
- [Methylene blue] — Chudoku Kenkyu, 2008External reference
- Methylene-blue-associated encephalopathy — J Am Coll Surg, 2007External reference
Related research, comparisons & guides
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Compiled by Peptide Library Editorial · Reviewed Aug 30, 2026 · Updated Nov 7, 2026 · Version 2
This Methylene Blue profile is compiled from published literature (5 cited studies linked above), public regulatory records and chemical registries. It describes what research reports; it is not medical advice, and nothing here is a dosing recommendation for humans. Peptide Library does not sell peptides. Editorial policy · How profiles are compiled · Report an error
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