What's up with Methylene Blue? Bryan Johnson's latest longevity trend explained

Silicon Valley biohacker Bryan Johnson recently announced on X (formerly Twitter), “My urine is now blue. Started Methylene Blue today” sparking curiosity across wellness circles. He’s one of several high-profile figures alongside Robert F. Kennedy Jr. and other longevity enthusiasts who hype methylene blue as a longevity and brain-boosting elixir

Originally invented in the late 1800s as a textile dye, methylene blue (methylthioninium chloride) found its way into medicine early treating conditions like malaria, urinary infections, and as a vital therapy for methemoglobinemia, a rare blood disorder impairing oxygen delivery. It remains FDA-approved only for this disorder, not for brain-boosting or anti-aging.

Bryan Johnson and fellow biohackers claim methylene blue enhances mitochondrial function, sharpens focus, and slows aging by reducing cellular damage. Animal studies and small-scale human trials hint at possible benefits like improved memory or cognitive decline prevention but no robust clinical evidence exists confirming these effects in humans.

My urine is now blue.

Started Methylene Blue today.

— Bryan Johnson (@bryan_johnson) August 5, 2025

Is it safe?
Low-risk or risky?
Methylene blue is generally safe at therapeutic doses typically under 2 mg per kg of body weight. But above 5–7 mg/kg, risks rise significantly, especially serotonin syndrome if mixed with antidepressants (SSRIs, SNRIs, MAOIs). Symptoms can include confusion, tremors, fever, and even fatal brain reactions.

Other side effects
Users may experience blue or green tinting of skin, urine, even stool, harmless but alarming. Nausea, headache, dizziness, and hemolytic anemia (especially for individuals with G6PD deficiency) have been reported.

Quality control issues
Supplements labeled “methylene blue” are unregulated and often unreliable. Some products sold online may even be industrial-grade dye, definitely not for human use. IV treatments at med spas are also risky; unsupervised infusions can lead to contamination or dosing errors.

For most people, the basics (good sleep, balanced diet, movement) remain far more proven for brain health than blue dye experiments.

If you're curious: consult a qualified physician. Definitely avoid it if you're on antidepressants, pregnant, or have kidney issues.