None of the information in this article constitutes medical advice, and is just the opinion of the writer(s). We recommend that patients follow their doctor's guidance in regard to dietary supplements.
Methylene blue is a century-old pharmaceutical dye that has become one of the most hyped compounds in the longevity and biohacking world. Originally used to treat a blood disorder called methemoglobinemia, it's now sold in dropper bottles as a nootropic and anti-aging supplement.
But does methylene blue actually improve cognition? Is there any evidence it slows aging? What are the safety risks, especially for people taking antidepressants? And is methylene blue better or worse than other popular longevity supplements like NAD+ boosters?
In this article we'll answer all of these questions and more, as we review the clinical evidence behind methylene blue to give our take on whether it's likely to be effective, and whether it's safe.
We'll also flag the most serious safety concerns, and compare methylene blue to other popular longevity supplements to pick our winners (and losers).
Key takeaways:
- One small human study suggests a modest short-term memory benefit
- Carries serious drug-interaction and safety risks
- We do not currently recommend methylene blue as a supplement
What Is Methylene Blue?
Methylene blue is a synthetic dye first produced in the 1800s that later became a medication.
At pharmaceutical doses, it's an FDA-approved treatment for methemoglobinemia, a condition in which the blood cannot carry oxygen properly.
In the body, it acts as an electron carrier in the mitochondria, the energy-producing structures inside cells. This mitochondrial activity is the basis for most of its proposed cognitive and anti-aging benefits.
It is also a potent inhibitor of monoamine oxidase A (MAO-A), an enzyme that breaks down serotonin. This property is central to its safety risks, which we discuss in the Is Methylene Blue Safe? section below.
Does Methylene Blue Improve Memory?
The strongest evidence for methylene blue's cognitive benefits comes from a single small study.
A 2016 clinical trial published in the Radiology journal found that a single low dose of methylene blue improved memory retrieval by around 7% and increased brain activity during attention and memory tasks.
This is a promising but preliminary result. It involved just 26 participants and tested only a single dose, so it does not establish that methylene blue produces meaningful or lasting cognitive enhancement.
We cannot identify any large or long-term clinical trials showing that methylene blue improves cognition in healthy adults.
Does Methylene Blue Reverse Aging?
Much of the longevity marketing around methylene blue is based on its effects on mitochondria, which tend to become less efficient with age.
However, these anti-aging claims rest almost entirely on laboratory and animal research.
We cannot identify any human clinical trials demonstrating that methylene blue extends lifespan or slows biological aging.
In our opinion, the gap between the marketing claims and the human evidence is wider for methylene blue than for most compounds marketed for longevity.
Is Methylene Blue Safe?
The safety data and mechanism of action is where methylene blue becomes genuinely concerning, and why we treat it differently from a typical supplement.
Methylene blue is a potent MAO-A inhibitor, and it's clinically shown to cause serotonin toxicity when combined with serotonergic drugs. This includes common antidepressants like SSRIs and SNRIs, and the resulting serotonin syndrome can be severe and, in rare cases, fatal.
The US FDA has issued a safety communication warning that methylene blue should generally not be given to patients taking serotonergic psychiatric medications.
Methylene blue is also contraindicated in people with G6PD deficiency, a common genetic enzyme disorder, because it's clinically shown to trigger hemolysis, the breakdown of red blood cells.
The average consumer has not undergone genetic testing to identify whether or not they have this deficiency.
Finally, methylene blue sold as a supplement is largely unregulated.
Pharmaceutical-grade methylene blue is held to strict purity standards, but industrial-grade versions sold online can contain heavy-metal contaminants, so consumers often cannot verify what they are actually taking.
For these reasons, we consider methylene blue's risk profile to be far higher than that of a typical longevity supplement.
Methylene Blue vs. Longevity Supplements
Here's how methylene blue compares to other popular longevity supplements in terms of evidence quality and safety, in our opinion:
Urolithin A
Urolithin A is a compound found in pomegranates (and marketed as Mitopure) that activates the body's process for clearing damaged mitochondria. Unlike methylene blue, it's clinically shown to improve muscle strength and markers of mitochondrial health in human trials.
It also has a clean safety profile, while methylene blue carries serious drug-interaction risks.
Urolithin A is the winner from both an evidence and a safety perspective.
Winner: Urolithin A
Tru Niagen
Tru Niagen is a popular NAD+ booster, a category of longevity supplements aimed at raising cellular NAD+ levels. As we documented in our Tru Niagen review article, it's well-tolerated and backed by human trials showing it reliably raises NAD+.
While the long-term longevity benefits of NAD+ boosters are still debated, Tru Niagen does not carry the serotonin syndrome or G6PD risks that methylene blue does.
Tru Niagen is the winner from a safety perspective.
Winner: Tru Niagen
Resveratrol
Resveratrol is one of the original longevity supplements, a polyphenol found in red wine and grapes. Its human evidence for longevity is mixed and largely unconvincing, similar to methylene blue.
However, resveratrol has a long safety record and does not carry methylene blue's drug-interaction risks.
Resveratrol is the winner from a safety perspective.
Winner: Resveratrol
