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MtApproved drug

Methylene blue

Methylene blue is an old dye that the US FDA approves as an IV drug for acquired methemoglobinemia, a blood condition. Low-dose oral use for aging is not approved or proven.

Approved in the US (IV): Provayblue, for acquired methemoglobinemiaNot approved for aging, memory or any oral useBoxed warning: serotonin syndrome with some antidepressants and opioids
OverviewDosingMixingResearchCommunitySafetyFAQSources

Methylene blue quick reference

TypeRedox dye (small molecule)
Studied forMethemoglobinemia; memory, mood
EvidenceApproved IV; small oral studies
RouteIV (label); oral in community
Half-lifeAbout 24 hours (IV label)

What is Methylene blue?

Old blue dye that the FDA approves as an IV drug.

Used orally for focus and energy.

No approved oral or anti-aging use.

How Methylene blue works

Redox cycling

Passes electrons back and forth between two forms.

Methemoglobin fix

Turns methemoglobin back into working hemoglobin.

MAO inhibition

Blocks MAO enzymes, which clashes with antidepressants.

Mitochondria

In lab tests it can carry electrons past blocks.

What Methylene blue is studied for

PeopleMethemoglobinemia

Approved IV treatment at 1 mg/kg.

PeopleMemory

26 adults: 7% more correct recalls after one oral dose.

PeopleBrain activity

fMRI showed more activity in attention and memory areas.

PeopleBipolar depression

195 mg daily eased depression and anxiety (37 people).

AnimalsBrain cell protection

Cell and animal work on oxidative injury.

Lab / cellsMitochondria

Acts as a backup electron carrier in lab studies.

Methylene blue dosing protocol

UseAmount
US label, IV1 mg/kg over 5 to 30 minutes
Repeat doseUp to 1 mg/kg one hour later if blood levels stay above 30% or symptoms continue
Moderate or severe kidney problemsOne 1 mg/kg dose only
Not allowedDo not give under the skin
Oral low-dose for agingNot established

From the Provayblue US prescribing information (openFDA, label effective May 2025). The label covers IV use for methemoglobinemia only.

LABEL, IV1 mg/kg over 5 to 30 minLabel
LABEL, REPEATUp to 1 mg/kg after 1 hourLabel
TRIAL, BIPOLAR195 mg daily by mouth vs 15 mgTrial
COMMUNITY RANGE5-20 mg daily by mouthCommunity

Label and trial amounts come from the sources below. Community amounts are what people report; they have not been tested.

Mixing

Pharmacy-grade only. Aquarium or industrial dye is unsafe.

Open the peptide calculator

What the research found

No human trial shows a longevity benefit. The closest human studies were small:

0trials showing an anti-aging benefit
195 mgoral daily dose in a 6-month bipolar disorder study (37 people); depression and anxiety scores improved versus 15 mg
1 mg/kgIV label dose for methemoglobinemia

Alda M et al. Br J Psychiatry 2017 (PubMed 27284082, NCT00214877); Provayblue US label. Another human study used one low oral dose and looked at brain scans only (PubMed 26961091).

Methylene blue community experience

What users report. Not tested in trials.

Positive reports

  • Mental clarity Some feel sharper and start tasks more easily.
  • Alertness A mild same-day lift is common.
  • Less fatigue Some feel less tired in short trials.

Negative & mixed

  • Blue urine and stains Skin, clothes and surfaces can stain.
  • Side effects Headache, nausea, dizziness, anxiety.
  • Restless or nothing Some sleep badly; others feel nothing.

Methylene blue stacking

Methylene blue + NAD+

Both in energy talk. Not studied together.

Methylene blue + MOTS-c

Different pathways. Not studied together.

Methylene blue + humanin

Not studied together.

Methylene blue side effects & safety

Common

  • Headache.
  • Nausea or diarrhea.
  • Low potassium or magnesium (IV label trials).
  • Muscle twitching (IV label trials).
  • Blue-green urine.
  • Dizziness or anxiety (community).

Less common

  • Serotonin syndrome with SSRIs, SNRIs, MAOIs, opioids (boxed warning).
  • Hemolytic anemia, especially in G6PD deficiency.
  • Anaphylaxis and seizure-like events.
  • False pulse oximeter readings.

Precautions

  • G6PD deficiency: label contraindication.
  • Serotonergic drugs: label says wait 72 hours after the last dose.
  • Pregnancy: label warns of possible fetal harm.
  • Breastfeeding: label says pause up to 8 days after treatment.
  • Kidney or liver problems raise exposure.

Our verdict on Methylene blue

A real medical drug with a serious interaction risk. Oral anti-aging use is unproven.

Methylene blue FAQ

Is methylene blue FDA approved?

Yes, IV, for acquired methemoglobinemia only.

Is it safe with antidepressants?

No. The label warns of fatal serotonin syndrome.

Does it improve memory?

One 26-person study showed a small gain after one dose.

Sources

  • Provayblue (methylene blue) US prescribing information via openFDA, effective 28 May 2025
  • Alda M et al. Methylene blue treatment for residual symptoms of bipolar disorder. Br J Psychiatry 2017, NCT00214877
  • Methylene blue modulates functional connectivity in the human brain. Brain Imaging Behav 2017 (PubMed 26961091)
  • Rodriguez P et al. Multimodal randomized functional MR imaging of the effects of methylene blue in the human brain. Radiology 2016 (PubMed 27351678)
  • Alternative mitochondrial electron transfer as a novel strategy for neuroprotection. J Biol Chem 2011 (PubMed 21454572)
  • Serotonin toxicity and urinary analgesics: methylene blue-induced serotonin syndrome, case report and review. Psychosomatics 2018 (PubMed 30104021)