Methylene blue

Methylene blue is a redox-active phenothiazinium drug. Its FDA approval treats acquired methemoglobinemia; cognition evidence is a small acute experiment, not a chronic nootropic program.

tier A · focus · 26 people in the acute oral fMRI trial

verdict

A 26-person single-exposure oral study found fMRI changes and a small memory-retrieval signal. It does not establish durable cognitive benefit, a chronic regimen, or long-term safety.

the core tension

The approved rescue indication is real, and a small acute cognition signal exists. The nootropic story becomes unreliable when it borrows IV approval, IV PK, or short-term task changes for chronic self-use while minimizing MAO-A, serotonin, opioid, G6PD, and hemolysis risks.

what it is

Methylene blue, or methylthioninium chloride, is a small redox-active phenothiazinium salt. The reviewed ProvayBlue product is a sterile IV formulation whose strength is expressed as trihydrate.

what it does

In methemoglobinemia, it is reduced to leucomethylene blue, which helps convert methemoglobin iron toward functional hemoglobin. It also potently inhibits MAO-A, which helps explain its dangerous serotonergic interactions.

origin

The page separates the defined chloride identity from the FDA-approved IV ProvayBlue formulation and from experimental oral cognition use.

does it work

It works for its acquired-methemoglobinemia indication. For cognition, one acute study in healthy adults reported task and fMRI changes; no chronic nootropic efficacy or long-term safety conclusion follows.

key facts

• molecular formula: C16H18ClN3S (anhydrous chloride identity)
• molecular weight: 319.9 g/mol (anhydrous chloride identity)
• amino acids: n/a (phenothiazinium salt, not a peptide)
• half-life: about 24 h in the reviewed IV product's human PK; not a chronic oral nootropic value
• type: redox-active phenothiazinium chloride
• CAS: 61-73-4
• 26 healthy adults in the acute cognition experiment
• 7% reported increase in correct memory-retrieval responses
• 24 h approximate IV-product human half-life

frequently asked questions

What is methylene blue approved to treat?

The reviewed FDA-approved IV product treats acquired methemoglobinemia in adults and children.

Is it an approved nootropic?

No. The methemoglobinemia approval is not chronic nootropic evidence. The cognition record shown here is one small, acute oral experiment.

Why are antidepressants and opioids a concern?

Methylene blue inhibits MAO-A, and the label warns that serotonergic drugs and opioids can contribute to serious or fatal serotonin syndrome.

Why does G6PD status matter?

The IV product is contraindicated in G6PD deficiency because it may be ineffective and can cause severe hemolysis and hemolytic anemia.

Is the 24-hour half-life a chronic oral-use number?

No. It comes from the IV product's human PK section. The page does not transfer it to a different oral formulation or repeated nootropic use.

related peptides

• semax: compare with this single-exposure oral cognition record
• selank: compare without transferring methemoglobinemia approval or IV PK

reptides grades the research record and cites the literature behind every call. research reference only; not medical advice.