Methylene Blue: What to Tell Patients Asking About the Nootropic Trend

Reviewed 7/15/26 by the NatMed Clinical Team

Top Takeaways

Evidence for cognitive enhancement and anti-aging benefits is weak. The only FDA-approved use remains methemoglobinemia.
Oral supplements carry real risks – including possible serotonin syndrome with serotonergic drugs and reproductive harm.

Hype around methylene blue for boosting energy, slowing aging, and as a cognitive enhancer isn’t waning. Consumers are seeking out these products – prepare for questions.

What is methylene blue?

Methylene blue, or methylthioninium chloride, is a synthetic dye and IV prescription medication. Prescription products are FDA-approved to treat methemoglobinemia, a life-threatening blood disorder. They’re also used in hospitals for septic shock, as a surgical dye, and to manage some overdoses. Non-prescription methylene blue is of interest for a variety of other uses, particularly related to cognitive function and aging.

Why is methylene blue trending?

In the brain, methylene blue is thought to donate electrons to the electron transport chain, promoting energy production. Because of this, it’s been garnering media attention as a nootropic. Many products sold online are promoted for energy and “mental clarity.” They often come as 1% solutions in dropper form or as capsules. 

Does methylene blue benefit cognitive function or aging?

It’s too soon to say – there is some human research showing that taking a single dose of methylene blue results in some neurological benefit while undergoing attention and short-term memory tasks, but strong clinical data for both cognitive function and aging are lacking. While not necessarily a trending use, it’s worth noting that there is some clinical research in patients with moderate Alzheimer disease showing that methylene blue 138 mg daily for 24 or 50 weeks modestly improves cognition when compared with placebo. But this is hard to interpret since higher or lower doses didn’t seem to help – more data are needed.

Is methylene blue safe?

It depends. Prescription products have been used safely, but there isn’t any good safety data on methylene blue supplements. Common side effects include changes in stool and urine color. And there are some notable interactions to keep an eye on. Methylene blue is a monoamine oxidase A inhibitor – IV use has resulted in serotonin syndrome, including fatalities. While this hasn’t been reported with oral use, patients taking serotonergic drugs (dextromethorphan, SSRIs, etc) or supplements (St. John’s wort, etc) should avoid it. Lastly, warn about use during pregnancy and breastfeeding – serious side effects have been reported in both fetuses and newborns. 

What’s the bottom line?

We don’t have enough data to say whether methylene blue will benefit any condition beyond its prescribed use. For now, given the limited evidence of benefit and potential safety concerns, advise skipping these products. Check out our methylene blue monograph for more details.