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Methylene blue

Longevity

AnecdotalMostly reports and preclinical work, not human trials.

A century-old dye and medication now promoted as a nootropic and mitochondrial aid.

Serotonin syndrome
The FDA-warned interaction between methylene blue and serotonergic antidepressants

What it is

A 19th-century textile dye that became a real medicine, and lately, a biohacker trend. It is the only entry in this catalog that is an FDA-approved prescription drug being sold and self-dosed as a supplement, which is exactly why it deserves the most caution here.

How it works

In experimental systems, low concentrations of methylene blue can shuttle electrons in the mitochondrial chain, while higher concentrations reverse to pro-oxidant behaviour. That dose-dependent flip is observed largely in cell and animal work and does NOT establish a safe or beneficial human nootropic window. It is also a potent MAO inhibitor, the source of its most dangerous interaction.

Which form to buy

Prescription IV methylene blue (ProvayBlue)Its actual approved use

FDA-approved as an INTRAVENOUS product for ACQUIRED methemoglobinemia. Consumer oral products are not that approved product.

The legitimate, supervised use, and it is not what is sold online.

"Pharmaceutical grade" oral dropsThe trend

Sold online for cognition and energy. Purity and concentration vary, and dosing is self-directed with no oversight.

A prescription drug being taken without a prescriber.

Industrial / aquarium methylene blueNever

Not manufactured to any human-use standard and may contain uncontrolled impurities, including heavy metals.

Not a cost-saving option.

What it actually does, graded

The IV pharmaceutical is the approved treatment for acquired methemoglobinemiaStrong

The approved indication for the intravenous product, given in hospital, not the hereditary form, and not the oral drops.

Cognitive enhancement in healthy peopleLimited

One small brain-imaging study showed increased functional MRI responses and modest memory effects, a single small study, not a basis for routine use.

Antidepressant effectsLimited

Some old, small psychiatric research; superseded and not established.

Longevity / anti-ageingNone shown

Cell and animal work only. No human outcome evidence whatsoever.

Treating neurodegenerative diseaseNone shown

Related compounds have been trialled in Alzheimer's without clear success.

Pros and cons

Pros
  • A real drug with a genuinely important emergency use
  • The mitochondrial mechanism is experimentally real, if unproven in people
Cons
  • ⚠️ Serotonin syndrome risk with antidepressants is the headline danger, this is a potent MAO inhibitor and the FDA has issued warnings
  • Turns urine and sometimes skin blue-green
  • The dose-response flip is experimental, and no human window of benefit has been established
  • Consumer products have no meaningful quality oversight
  • It is a prescription drug being self-administered outside medical care

What to expect

  • Blue-green urine within hours, the most reliable and harmless effect.
  • The cognitive research is a single small imaging study; there is no established regimen behind the trend.

Interactions

AvoidSerotonergic drugs. SSRIs, SNRIs, MAOIs, and also OPIOIDS, DEXTROMETHORPHAN, linezolid, buspironeThe most serious interaction in this catalog. Methylene blue is a potent MAO inhibitor and can precipitate serotonin syndrome, which can be fatal. FDA's boxed warning attaches to the IV product; oral cases exist too, with incidence and threshold unknown, which argues for more caution with self-dosing, not less.
AvoidG6PD deficiencyCan cause severe haemolysis, dangerous, and many people do not know they have G6PD deficiency.
AvoidPregnancyAssociated with fetal harm.
CautionKidney impairmentReduced clearance raises exposure.

Is it for you?

Probably worth it if
  • Honestly: no self-directed use case. The approved indication is a hospital emergency.
Probably skip it if
  • You take any serotonergic drug (antidepressants, but also opioids and dextromethorphan) this combination can be fatal
  • You want a nootropic, one small imaging study does not justify self-dosing a prescription drug

Who should avoid it

  • Anyone on serotonergic medication of any kind
  • People with G6PD deficiency, kidney impairment, or who are pregnant
  • Anyone considering non-pharmaceutical-grade product

Research on this supplement

Papers about this supplement, not proof of the claims above. A title says what was studied, which is sometimes a negative result or a different question entirely.

What the evidence says

Real clinical use exists for methaemoglobinaemia. For cognition and longevity in healthy people the human evidence is essentially absent; most of what circulates is preclinical or personal report.

What studies used

No established supplement dose, it is a prescription drug at clinical doses. n/a.

Reported from published studies and product labelling — a record of what was used in research, not a recommendation. What is right for you is a conversation with a clinician.

Watch out for

  • Serious interaction with SSRIs and other serotonergic drugs (serotonin syndrome)
  • Purity of non-pharmaceutical product is a genuine unknown
  • This is a drug, not a vitamin, treat it that way

Evidence base

S30,316 research papers
established literature

Large human evidence base: several phase 3 or 4 trial reports, plus multiple meta-analyses or systematic reviews.

This letter measures how much human research exists, not whether it works for you — the tier above (Anecdotal) is the read on quality.

Research (12)

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Where next

Every supplement in the catalogThe full shelf, grouped and evidence-tiered.→The compound indexSteroids, nootropics and research chemicals.→The peptide indexInjectable peptides and what trials used.→