Evidence review: Open Peptide Project (verified against primary PubMed, ClinicalTrials.gov & FDA records) · Last checked 2026-10-27. ← Back to Evidence Library

Methylene blue (methylthioninium chloride, ProvayBlue): what the evidence says

Name: Methylene blue (methylthioninium chloride, ProvayBlue)
Published: 2026-10-27

At a glance

What it is: Caution Not a peptide. Methylene blue is a phenothiazine dye, a small molecule, not an amino-acid chain. It is listed here only because it is sold alongside research peptides. ^R1 It is FDA-approved as ProvayBlue (2016), an IV treatment for acquired methemoglobinemia in children and adults. ^{R2, R3}

What the evidence says: Human the label's efficacy data come from 31 adults in an open-label study and a registry: 26 of 28 with a baseline value had methemoglobin fall by at least half at first check. ^R3 Small studies of oral doses for memory, bipolar depression, claustrophobia and PTSD report modest or mixed effects; none is large or replicated. ^{R4, R5, R6, R7}

Biggest risks: boxed warning: serious or fatal serotonin syndrome when combined with serotonergic drugs (SSRIs, SNRIs, MAOIs) or opioids. Contraindicated in G6PD deficiency (risk of hemolytic anemia) and in severe allergy to thiazine dyes. ^R3

Rating


Human Human evidence	Moderate (approved use): uncontrolled label studies, n = 31 ^R3 · Limited or Very limited (other uses): small trials ^{R5, R4}
Animal Animal / lab evidence	Not reviewed
Regulatory	FDA-approved ^R2 · not on FDA's 503A or 503B bulk-substance category lists and not on FDA's compounding safety-risk page ^{R8, R9, R10} · not named by WADA ^R11
Established human dose	Yes, label dose (see Study details)

Evidence verdict: Acquired methemoglobinemia: Moderate (FDA-approved; label efficacy from 31 patients in uncontrolled studies) · Bipolar depression (add-on): Limited (one 37-person crossover RCT) · Memory, attention, fear extinction: Very limited (small studies) · Anti-aging or 'mitochondrial support': No human data

This page reports what studies used. It is not dosing advice.

Legend: HUMAN data · ANIMAL / LAB data · UNKNOWN · UNVERIFIED: not yet confirmed against a primary source

About the evidence: the approved use rests on long clinical practice plus small uncontrolled studies rather than RCTs, which is why it is graded Moderate. The brain and mood studies are small, short and mostly single-site, and the large dementia trials tested a related compound, not methylene blue.

What is it?

Related pages: ss-31, glutathione, bam15.

Does it work?

Human Acquired methemoglobinemia (approved): in 31 adults across an open-label study and a registry, 26 of 28 with a baseline value had methemoglobin fall by at least 50% at the first check (median 2.7 hours after infusion). ^{R3, R12}
Human Memory and attention (n = 26): one oral dose increased brain activity on fMRI during attention and memory tasks and gave 7% more correct memory answers than placebo. ^{R4, R13}
Human Bipolar disorder (crossover RCT, n = 37): as an add-on, improved leftover depression and anxiety vs a very low comparison dose; no effect on thinking or memory. ^{R5, R14}
Human Claustrophobia (n = 42): helped fear extinction when given after a successful exposure session, but people who were still fearful after the session tended to do worse. ^R6
Human PTSD (n = 42): with brief exposure therapy, gains did not differ from standard therapy at 3 months, though some response measures favored methylene blue. ^R7
Human Alzheimer disease: phase 3 trials tested hydromethylthionine (a related, reduced form), not methylene blue, and did not show benefit on the co-primary endpoints. ^R15
Human Shock (off-label IV): a 2026 meta-analysis of 9 RCTs (535 adults) found no clear survival benefit. ^R16
Unknown Anti-aging or 'mitochondrial support': no human data.

Is it safe?

Human Boxed warning: serotonin syndrome, sometimes fatal, with SSRIs, SNRIs, MAOIs and opioids. ^R3
Human A review of 50 published serotonin-syndrome cases found all involved IV methylene blue given with serotonergic drugs; one person died. ^R17
Human Contraindicated in G6PD deficiency (hemolytic anemia) and in severe allergy to methylene blue or other thiazine dyes. ^R3
Human Other label warnings: anaphylaxis, hemolytic anemia, false pulse-oximeter readings, dizziness and visual effects (avoid driving until they resolve) and possible fetal harm. Most common side effects: headache, low potassium, diarrhea, low magnesium, muscle jerks, nausea and seizure-like events. ^R3

Gray-market vials: extra risks

A gray-market vial has no quality control and no guarantee of identity, strength or sterility. We test retail vials blind under the Open Peptide Standard; see /tests/. A passing test covers one batch on one date and does not mean the compound is safe.

Is it legal?

US: FDA-approved, prescription IV injection (ProvayBlue) for acquired methemoglobinemia. ^{R2, R3} Oral use for memory, mood or anti-aging is not an approved use. ^R3
Compounding: not on FDA's 503A or 503B bulk-substance category lists and not on FDA's compounding safety-risk page. ^{R8, R9, R10}
Sport: not named on WADA's 2026 Prohibited List. ^R11

Study details

These are amounts researchers used, not recommendations.

Study	People / model	Route	Amount used	Follow-up	Reported	Citation
ProvayBlue label	Children and adults with acquired methemoglobinemia	IV over 5–30 min	1 mg/kg; a repeat dose of up to 1 mg/kg after 1 hour if needed	1–2 doses	Approved dose	^R3
Rodriguez 2016	26 healthy adults	Oral	Single low dose (registry lists 280 mg)	Single dose	More fMRI activity; 7% more correct memory answers	PMID 27351678
Alda 2017 (crossover RCT)	37 adults with bipolar disorder	Oral	195 mg/day vs 15 mg/day	6 months each arm	Less depression and anxiety; no cognitive effect	PMID 27284082
Telch 2014 (RCT)	42 adults with claustrophobia	Oral, after sessions	260 mg	1-month follow-up	Helped only after successful sessions	PMID 25018057
Zoellner 2017 (RCT)	42 adults with PTSD	Oral, after sessions	260 mg	3-month follow-up	No difference vs standard therapy	PMID 28686823

Full reference list (PubMed, CT.gov, FDA and WADA checked Oct 27, 2026)

^R1 PubChem CID 6099, Methylene Blue (synonyms methylthioninium chloride, Provayblue), checked Oct 27, 2026. https://pubchem.ncbi.nlm.nih.gov/compound/6099
^R2 Drugs@FDA, ProvayBlue (methylene blue), application NDA204630 (openFDA drugsfda record checked Oct 27, 2026). https://www.accessdata.fda.gov/scripts/cder/daf/index.cfm?event=overview.process&ApplNo=NDA204630
^R3 ProvayBlue prescribing information, label published May 28, 2025 (DailyMed, checked Oct 27, 2026). https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=4f6848e5-35ed-4046-b13c-3032b5ba3232
^R4 Rodriguez P, et al. Radiology. 2016. PMID 27351678
^R5 Alda M, et al. Br J Psychiatry. 2017. PMID 27284082
^R6 Telch MJ, et al. Am J Psychiatry. 2014. PMID 25018057
^R7 Zoellner LA, et al. J Clin Psychiatry. 2017. PMID 28686823
^R8 FDA, 503A bulk drug substances categories list (updated May 14, 2026). https://www.fda.gov/media/94155/download
^R9 FDA, 503B bulk drug substances categories list (updated Mar 21, 2025). https://www.fda.gov/media/94164/download
^R10 FDA, Certain bulk drug substances for use in compounding that may present significant safety risks (content current Apr 22, 2026). https://www.fda.gov/drugs/human-drug-compounding/certain-bulk-drug-substances-use-compounding-may-present-significant-safety-risks
^R11 WADA. The 2026 Prohibited List, full list checked; compound not named. https://www.wada-ama.org/sites/default/files/2025-09/2026list_en_final_clean_september_2025.pdf
^R12 ClinicalTrials.gov NCT03395223, open-label single-arm study in acquired methemoglobinemia, cited in the ProvayBlue label (CT.gov API v2, checked Oct 27, 2026). https://clinicaltrials.gov/study/NCT03395223
^R13 ClinicalTrials.gov NCT01836094, methylene blue fMRI and cognition study in healthy adults, UT Health San Antonio, completed (CT.gov API v2, checked Oct 27, 2026). https://clinicaltrials.gov/study/NCT01836094
^R14 ClinicalTrials.gov NCT00214877, methylene blue add-on for residual bipolar symptoms, crossover RCT (CT.gov API v2, checked Oct 27, 2026). https://clinicaltrials.gov/study/NCT00214877
^R15 Wischik CM, et al. J Prev Alzheimers Dis. 2026. PMID 41570392
^R16 Rodríguez-Lima DR, et al. J Clin Med. 2026. PMID 42355649
^R17 Zuschlag ZD, et al. Psychosomatics. 2018. PMID 30104021

Disclaimer

This page is for education and harm reduction, not medical advice or a recommendation to use Methylene blue (methylthioninium chloride, ProvayBlue). This is a prescription medicine. Use it only under the care of a licensed clinician; do not buy it from research-chemical or gray-market sellers. Report problems to FDA MedWatch (https://www.fda.gov/safety/medwatch).