Methylene blue

ProvayBlue (not a peptide) · F-tier (Dr. Alex Tatem) · Limited evidence

A real medicine with real uses — reversing a rare blood disorder and helping surgeons find the ureters — that has been rebranded online as a mitochondrial longevity booster without evidence for that use.

Dr. Tatem’s take

F tier. Great for finding a ureter or treating methemoglobinemia, but “there is absolutely zero evidence to support any of this in a longevity context,” it can be “extremely toxic if you overdose,” and it can stain you blue.

In Dr. Tatem’s tier list

• Not technically a peptide, but so popular online it had to be included.
• In training he used it to find the ureters during surgery: injected IV, it clears through the kidneys within seconds and turns urine dark blue.
• Its real medical use is methemoglobinemia, a rare condition (often from nitrate poisoning) where red blood cells can’t carry oxygen.
• Claims that it rejuvenates mitochondria and reduces oxidative stress have no longevity evidence; it can be toxic in overdose and permanently stain skin and nails.
• “If you’re trying to find a ureter… this gets an S tier rating, but for our purposes today, methylene blue gets a solid F tier.”

History & background

Methylene blue was synthesized in 1876 by Heinrich Caro at BASF as a textile dye — Germany’s first patented coal-tar dye. In the 1880s Paul Ehrlich found it stained nerve cells and malaria parasites and used it against malaria, one of the first synthetic drugs used to treat an infection.

It has been used in medicine ever since; FDA formally approved it as ProvayBlue in 2016. Its derivative (HMTM) was tested in Alzheimer’s disease in the 2010s–2020s with inconclusive results. The 2020s longevity trend is not based on human trials.

Benefits

• Reverses methemoglobinemia (blood that can’t carry oxygen).
• Small trials: a single dose modestly improved memory-task brain activity (n=26); 195 mg/day helped residual depression and anxiety in bipolar disorder (n=37).

Risks

• Boxed warning: serious or fatal serotonin syndrome when combined with SSRIs, SNRIs, MAOIs or some opioids.
• Dangerous in G6PD deficiency (hemolytic anemia).
• Toxic in overdose; stains skin, urine, tongue and nails blue.
• Makes pulse oximeters read falsely low.
• Wellness products have uncertain content.

Dosing protocols (informational, labeled by evidence)

• Clinical trial / label: FDA label (ProvayBlue, methemoglobinemia) — 1 mg/kg (may repeat), IV, Acute, Acute
• Clinical trial / label: Low-dose cognition fMRI RCT — Single low oral dose (exact mg not given in the abstract), Oral, Single, Single
• Community (bro science): Wellness drops — 1–20 mg/day (product labels on 1–2% solutions), Oral, Daily, Ongoing

Status: FDA-approved (ProvayBlue, 2016) only as an IV treatment for acquired methemoglobinemia. Oral “wellness” products are not approved for any use.

Grade and commentary: Dr. Alex Tatem. Watch: The Truth About Popular Peptides (What Works, What’s Overhyped) | Peptide Tier List pt.1. Subscribe: @DrAlexTatem.