Important limitations
- Safety, Contraindications & Monitoring: Why methylene blue requires serious caution despite its broad research interest
- Future Research: Where methylene blue still needs stronger validation
Methylene Blue
Methylene blue is a long-established synthetic medicine with a wide range of clinical and research applications.
Dosing & scaling, explained
No mass-based amount example with adequate calculation context is available for this compound. This is educational source context, not a protocol or recommendation.
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No independently verified schedule
Evidence context
No clinical amount or schedule is inferred from this material. Source verification is pending, and every displayed amount remains educational context rather than guidance.
Storage, handling and interpretation
Product identity
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Storage & handling
Follow the product label, certificate and validated laboratory SOP; no universal storage assumption is applied here.
Prepared solutions
Label concentration and preparation date, use sterile technique where applicable, and follow a validated stability protocol.
Reported protocols for Methylene Blue
What published studies and recent community write-ups report about amounts, timing and course length. 6 clinical, 1 preclinical and 2 community-reported rows, each linked to its source. These are descriptions of what others report, not instructions, and nothing here is medical advice.
| Context | Dose | Frequency | Route | Course | Source |
|---|---|---|---|---|---|
| Clinical6 rows | |||||
| FDA label, ProvayBlue for acquired methemoglobinemiaAdults and children with acquired methemoglobinemia | 1 mg/kg | Single dose; a second 1 mg/kg dose may follow one hour later if methemoglobin stays above 30% or symptoms persist | Intravenous over 5-30 minutes (never subcutaneous) | One treatment episode, maximum two dosesNot applicable; patients with moderate or severe renal impairment receive a single dose only | DailyMed, National Library of Medicine2024 |
| The 2024 label states that doses outside 1 mg/kg are not recommended, that methylene blue has a half-life of roughly 24 hours in humans, and that a single dose of 20 mg/kg or more of a methylene blue class product has caused fatal hemolysis. Its boxed warning covers serotonin syndrome with SSRIs, SNRIs, MAOIs and opioids, and patients are told to avoid serotonergic drugs for 72 hours after the last dose. | |||||
| Septic shock adjunct, randomized trial91 adults with septic shock in a single Mexican intensive care unit | 100 mg in 500 mL saline | Once daily for 3 days, started within 24 hours of shock diagnosis | Intravenous infusion over 6 hours | 3 daysNot applicable | Critical Care (PubMed)2023 |
| Time to coming off vasopressors fell from a median of 94 hours to 69 hours, with one extra vasopressor-free day and shorter intensive care and hospital stays, while mortality and ventilator days were unchanged. The authors call for larger trials because this was a single-center study of 91 patients. | |||||
| Alzheimer's disease phase 2 dose-finding trial (Rember)321 adults with mild or moderate Alzheimer's disease not taking cholinesterase inhibitors or memantine | 69, 138 or 228 mg/day of methylthioninium (given as 30, 60 or 100 mg methylthioninium chloride capsules) | Daily | Oral | 24 weeks, with blinded extensions to 50 weeksNone | Journal of Alzheimer's Disease (PubMed)2015 |
| The primary analysis at 24 weeks was negative overall, but the 138 mg/day group showed benefit in prespecified subgroups: a 5.4-point ADAS-cog advantage in moderate disease and slower regional blood flow decline in mild disease. The highest dose underperformed because the 100 mg capsules dissolved and absorbed poorly, and the most common adverse events were diarrhea and urinary symptoms; the sponsor later switched to the reduced form LMTM. | |||||
| Bipolar disorder residual symptoms, crossover trial37 adults with bipolar disorder taking lamotrigine | 195 mg/day (active) versus 15 mg/day (used as the placebo because the drug colors urine) | Daily | Oral | 3 months on each dose, 6 months totalCrossover between doses, no washout described | British Journal of Psychiatry (PubMed)2017 |
| The 195 mg dose improved residual depression and anxiety scores compared with 15 mg, while mania ratings stayed low and cognitive measures did not change. Side effects were mild and transient, but the design could not use a true placebo and the sample was small. | |||||
| Fear extinction and contextual memory, single-session study42 adults with marked claustrophobic fear | 260 mg total (three 86.66 mg capsules), chosen to match 4 mg/kg from rodent work | One capsule immediately after six 5-minute exposure trials, one at bedtime, one the next morning | Oral | About 24 hours of dosing, retested 1 month laterNot applicable | American Journal of Psychiatry (PubMed)2014 |
| Participants who ended the exposure session with low fear kept more of their gains a month later on methylene blue than on placebo, but those who still had moderate or high fear tended to do worse, consistent with the drug strengthening whatever memory was formed. Contextual memory improved regardless of fear level. | |||||
| Memory and attention fMRI trial, single dose26 healthy adults aged 22-62 | 280 mg (about 4 mg/kg for a 70 kg adult) | Single dose, scanned one hour later | Oral immediate-release capsules | Single sessionNot applicable | Radiology (PubMed Central)2016 |
| Methylene blue increased fMRI responses in the insula during a vigilance task and in prefrontal, parietal and occipital regions during a short-term memory task, with a 7% rise in correct memory retrieval. Thirteen people received drug and thirteen placebo, so the result is preliminary and says nothing about repeated dosing. | |||||
| Preclinical1 row | |||||
| Preclinical hormetic dose rangeRats and mice in memory, metabolic lesion and neurodegeneration models | 0.5-4 mg/kg (memory enhancement most reliable at 4 mg/kg; a single 1 mg/kg dose raised brain cytochrome oxidase activity by about 30%) | Single post-training doses or short daily courses | Intraperitoneal or systemic injection in animals | Hours to days around a learning taskNot applicable | Progress in Neurobiology (PubMed)2012 |
| This review describes an inverted-U dose response: low doses act as an alternative electron carrier that boosts mitochondrial respiration and memory consolidation, while doses above roughly 10 mg/kg impair the same functions and 50-100 mg/kg are harmful. The human figures of 0.5-4 mg/kg quoted by community guides trace back to this animal literature. | |||||
| Community-reported2 rows | |||||
| Community low-dose oral use | 5-20 mg/day (a 1% solution gives about 0.5 mg per drop, a 2% solution about 1 mg per drop) | Once daily or split between morning and early afternoon | Oral drops of USP-grade solution | Not specified; described as ongoing supplement-style useNone described | Community resource2026 |
| This 2026 guide separates three very different exposures: hospital 1 mg/kg infusions, single 260-280 mg research doses, and the 5-20 mg a day that online users describe, and it says the last has no clinical standard behind it. It repeats review-level warnings that side effects climb above about 7 mg/kg and that serotonergic drugs are the main interaction hazard. | |||||
| Community nootropic dosing chart | 5-30 mg/day (0.5-4 mg/kg quoted as the research window) | Once daily, typically in the morning | Oral (the page's subcutaneous unit tables are described as a measurement reference only) | 8-16 week courses in its supply tablesNone described | Community resource2026 |
| This 2026 chart cites a 16-volunteer pharmacokinetic study for a terminal half-life of about 5-6.5 hours and 72% oral bioavailability, which is shorter than the roughly 24-hour figure on the ProvayBlue label. It warns that industrial dye grades can carry heavy metals and that low-dose oral use is off-label. | |||||
How a course is commonly described
- Hospital antidote: hoursClinical
For acquired methemoglobinemia the labeled course is a single 1 mg/kg intravenous dose over 5-30 minutes, repeated once after an hour only if methemoglobin remains above 30%. Urine and sometimes skin turn blue-green, and clinicians watch for serotonin syndrome for several hours in anyone taking serotonergic drugs.
- Single-dose cognition studies: one dayClinical
The human memory and extinction studies used one oral dose of 260-280 mg, roughly 4 mg/kg, timed an hour before scanning or immediately after a therapy session. Effects were measured within a day to a month, and no study has repeated these doses over weeks.
- Community weeks 1-4Community-reported
Online guides describe starting with a few milligrams of USP-grade solution in the morning and settling at 5-20 mg a day, split if a second dose is wanted before early afternoon to avoid sleep disruption. Blue urine from the first dose is the universal report; subjective focus or energy changes are described as modest.
- Community weeks 4-16Community-reported
Supply tables on community sites plan 8-, 12- and 16-week courses at about 10 mg a day, with no agreed break afterward. Nothing in the published literature tests low daily doses over these durations, so the course length is a convention, not a studied schedule.
- Clinical comparison: monthsClinical
The longest controlled oral courses are 3 months at 195 mg a day in bipolar disorder and 24-50 weeks at 69-228 mg a day in Alzheimer's disease, both at ten to forty times the community dose. These trials reported diarrhea and urinary symptoms as the main complaints, and the Alzheimer's program moved on to a different redox form of the molecule.
- Methylene blue's only approved use is intravenous treatment of acquired methemoglobinemia. Every oral regimen above, from the 280 mg research dose to the 5-30 mg community dose, is off-label, and the low daily doses have never been tested in a controlled trial.
- The drug is a potent reversible MAO-A inhibitor. The FDA label carries a boxed warning for serotonin syndrome with SSRIs, SNRIs, MAOIs, opioids and related drugs, and the product is contraindicated in G6PD deficiency because of hemolysis; these risks apply to oral use as well.
- Dose response is hormetic in animals, with benefit at 0.5-4 mg/kg and harm above about 10 mg/kg, and methylene blue itself causes methemoglobinemia at high doses. Sources disagree on half-life (about 24 hours on the label versus 5-6.5 hours in one oral pharmacokinetic study), so community timing rules rest on uncertain footing.
Sources for this section (9)
- PROVAYBLUE (methylene blue) injection: Prescribing Information
- Early adjunctive methylene blue in patients with septic shock: a randomized controlled trial
- Tau aggregation inhibitor therapy: an exploratory phase 2 study in mild or moderate Alzheimer's disease
- Methylene blue treatment for residual symptoms of bipolar disorder: randomised crossover study
- Effects of post-session administration of methylene blue on fear extinction and contextual memory in adults with claustrophobia
- Multimodal Randomized Functional MR Imaging of the Effects of Methylene Blue in the Human Brain
- Neurometabolic mechanisms for memory enhancement and neuroprotection of methylene blue
Plus 2 community resources (dosing guides, forum threads and vendor write-ups), reported above but not linked.
How Methylene Blue is being studied to work
This process map organizes available educational context. Individual claims remain subject to source-level verification.
- 1
Mechanism of Action
How methylene blue acts as a redox agent and mitochondrial electron carrier
Overview
Methylene blue (methylthioninium chloride) is a synthetic phenothiazine dye that shuttles electrons inside cells, which is why it reverses methemoglobinemia at low doses, acts as a potent reversible monoamine oxidase A inhibitor, and is being studied as a mitochondrial and tau-directed drug. In the United States it is an FDA-approved intravenous drug (ProvayBlue, approved 2016) for acquired methemoglobinemia, with a boxed warning for serotonin syndrome when combined with serotonergic drugs or opioids and a contraindication in G6PD deficiency. Published oral trials have used single doses of 260-280 mg for memory and fear extinction, 195 mg a day for three months in bipolar disorder and 69-228 mg a day for up to 50 weeks in Alzheimer's disease, while the low-dose oral use promoted online (roughly 5-30 mg a day) has never been tested in a controlled trial and is not an approved use.
What researchers are exploring
These themes organize the educational information currently available. Individual claims remain under source review and are not treatment claims.
- 1
Mechanism of Action
How methylene blue acts as a redox agent and mitochondrial electron carrier
- 2
Methylene Blue in Brain Aging
Why it is studied in neurodegeneration, mitochondrial dysfunction, and age-related cognitive decline
- 3
Alzheimer's Disease & Tau / Amyloid Research
Potential relevance to amyloid processing, tau aggregation, and cognitive decline
- 4
Parkinson's Disease & Neuroprotection
Dopaminergic preservation, oxidative stress reduction, and model-based evidence
- 5
Memory and Cognitive Function
Cytochrome oxidase activity, ATP generation, and memory-related findings
- 6
Methylene Blue in Skin Aging
Oxidative stress reduction, collagen support, UV protection, and skin quality
What is known and what still needs verification
Available context is organized without assigning unsupported study models or evidence grades.
- Not graded
Research Status & Clinical Context
Why this page uses a research-plus-clinical framing rather than a casual supplement-style format
- Not graded
Mechanism of Action
How methylene blue acts as a redox agent and mitochondrial electron carrier
- Not graded
Methylene Blue in Brain Aging
Why it is studied in neurodegeneration, mitochondrial dysfunction, and age-related cognitive decline
- Not graded
Alzheimer's Disease & Tau / Amyloid Research
Potential relevance to amyloid processing, tau aggregation, and cognitive decline
Chemistry identifiers
Sequence, synonyms and registry identifiers as recorded in PubChem, the National Library of Medicine's open chemistry database. Formula, mass and CAS number are summarized at the top of the page.
Also listed as
Methylthioninium chloride, ProvayBlue, Basic Blue 9, C.I. 52015, Urolene Blue, UNII 8NAP7826UB, DrugBank DB09241, CHEBI:6872
InChIKey
CXKWCBBOMKCUKX-UHFFFAOYSA-M
IUPAC name
[7-(dimethylamino)phenothiazin-3-ylidene]-dimethylazanium chloride
Limitations and unknowns
Sources
1 link carried over from the earlier page, awaiting verification.