Videos of actors, podcasters and “biohackers” sipping or swallowing something bright blue have turned methylene blue into a minor wellness phenomenon. It is being described online as “brain fuel”, a “limitless pill” and a “game changer” for mental clarity and longevity. At the same time, doctors, neuroscientists and toxicology experts are warning that the claims racing around social media are far ahead of the evidence.Methylene blue is not new. It was invented in the 19th century as a dye. It does have legitimate medical uses. But the way it is being used and promoted now, especially in unregulated form, taken daily and combined with other medications, is very different from how regulators and clinicians intend it to be used.
What methylene blue is actually for
Methylene blue was first synthesised in 1876 to dye textiles. In 1891, doctors discovered it could help treat malaria, and it entered medicine as a niche therapy long before the current wave of interest.Today, in the United States, methylene blue is approved by the Food and Drug Administration to treat methemoglobinemia, a rare blood disorder, sometimes inherited and sometimes triggered by drugs or toxins, in which red blood cells cannot transport oxygen properly and the skin can take on a blue tinge. At clinically appropriate doses, methylene blue can reverse this, restoring oxygen transport. It appears on the World Health Organization’s essential medicines list as part of the basic toolkit every health system should have.According to FDA and clinical use, it is also used in other specific medical settings. Doctors can use it to help reverse cyanide poisoning and a life-threatening complication called vasoplegic syndrome, where blood vessels lose their ability to constrict. In oncology, it may be used to manage certain chemotherapy-related encephalopathies, and surgeons use it as a stain to map out lymph nodes, vessels or abnormal tissue during operations.Outside human medicine, methylene blue is used inaquariums and fish care to treat parasites and conditions such as swim bladder disease. Industrially, it still appears as a synthetic dye in some textiles and printing processes.Those are tightly defined roles: prescribed, dosed and monitored in controlled settings. None of that is the same as healthy people taking daily drops or pills bought online to boost mood, focus or “longevity”.
How it became a “limitless pill” online
The recent wave of attention has come from social media, podcasts and wellness culture rather than from new regulatory approvals.Clips circulated of Robert F. Kennedy Jr. on a plane, placing blue liquid into a glass of water. While he did not confirm it was methylene blue, that is how it was widely interpreted.On The Joe Rogan Experience, Mel Gibson and Joe Rogan discussed methylene blue, saying “this stuff works,” while Rogan noted he had heard claims ,via RFK Jr., that it could have “profound effects on your mitochondria.”US podcaster Gabby Reece has told listeners she has been trying methylene blue “in different scenarios”.Biohacker Bryan Johnson, known for his attempts to reverse his biological age, has tried methylene blue as part of his regimen, sharing details such as his urine turning visibly blue. He has since stopped using it.Wellness influencers describe methylene blue as one of the “best kept secrets in biohacking”, a supposed nootropic that can sharpen focus, stabilise mood, support mitochondrial function and slow ageing. Some call it a “limitless pill”, borrowing from the film in which a tablet suddenly unlocks extraordinary cognitive ability. Others suggest it could ease jet lag or broadly enhance resilience.Alongside this, there have been much stronger, unproven claims online, such as people suggesting it can help cure cancer or treat a wide range of chronic conditions. These are anecdotal reports, not approved indications.At the same time, established clinicians and researchers are repeatedly emphasising that most of the work behind the hype comes from animal studies and cell models, not robust human trials.
What the science actually shows so far
There is a scientific rationale for why methylene blue attracted attention in neurology and ageing research, but it is at an early stage and often misrepresented.Professor Lorne J. Hofseth of the University of South Carolina told Science Alertthat methylene blue can cross the protective barrier that surrounds the brain. Laboratory and animal studies have suggested that, at certain doses, it might support mitochondrial function, the energy-producing processes inside cells, and could influence memory and learning mechanisms.Much of this work has been done in rats or in tissue and cell cultures. In those models, researchers have reported improvements in memory performance or cellular resilience when methylene blue is present. Some small human studieshave suggested modest improvements in memory tasks; others have not found significant effects on thinking or cognition.Attempts to repurpose methylene blue as a treatment for Alzheimer’s disease have not delivered convincing results. Dr Ian Musgrave of the University of Adelaide told The Guardian that methylene blue “largely failed in human clinical trials for treatment of Alzheimer’s disease”. He noted that it has antioxidant properties and “promising results in tissue culture”, but added that there is “currently no evidence in humans that it has significant anti-ageing effects”.Kan Cao, PhD, associate chair in the Department of Cell Biology and Molecular Genetics at the University of Maryland and founder of a skincare line that includes methylene blue, told Health that while some findings are encouraging, “they were predominantly done on animals, not humans”.So far, the picture from experts is consistent: there are interesting signals in preclinical research; there are some small and mixed human data; and there is not yet strong, reproducible evidence in people to justify the sweeping claims made in some biohacking circles.Neuroscientist Anne-Sophie Fluri summed up that gap in an interview with the Mail:“Without solid evidence in humans, these claims are at best speculative and at worst potentially dangerous. The brain is not a machine you can casually ‘optimise’ like a smartphone.”
Risks, side-effects and regulatory concerns
Alongside the uncertain benefits, there are clear and documented risks.Because methylene blue affects serotonin pathways and inhibits monoamine oxidase A (MAO-A), taking it together with certain antidepressants and other serotonergic drugs can raise the risk of serotonin syndrome. A paperby Ramsay RR, Dunford C and Gillman PK, titled “Methylene blue and serotonin toxicity: inhibition of monoamine oxidase A (MAO A) confirms a theoretical prediction”, reported that methylene blue can contribute to serotonin toxicity.Serotonin syndrome is rare but potentially serious. It occurs when serotonin levels in the brain become too high, often when medications or substances interact. Symptoms can include shivering, diarrhoea, muscle rigidity, agitation, confusion, fever and seizures. In severe cases, it can be life-threatening.Paradoxically, inappropriate dosing can also trigger methemoglobinemia, the very blood disorder methylene blue is meant to treat at controlled doses. Overuse or incorrect formulations raise that risk.Other reported side-effectsinclude pain in the extremities, nausea, sweating, and changes in the colour of the tongue and skin. Many users also notice that their urine turns blue, which is a predictable but still disconcerting effect.The FDA has previously intervened when methylene blue was promoted as an unapproved treatment. In 2020, the agency issued warnings to wellness centres offering it as a therapy for long COVID. Biohacking advocates, including Dr Pierre Kory, author of The War on Ivermectin, have spoken about methylene blue as boosting “mitochondrial respiration” in interviews, such as one withChildren’s Health Defense in 2022. But these uses are not authorised indications, and regulators have repeatedly stressed that methylene blue should not be offered as a generalised cure or rejuvenation treatment.
What doctors and health experts are actually advising
Across interviews and commentaries, clinicians and scientists are largely aligned on three points.First, methylene blue has real, established medical uses. It is an important emergency drug for specific, serious conditions such as methemoglobinemia and cyanide poisoning, and a useful tool in surgery and oncology. In those settings, it is dosed, monitored and used under medical supervision.Second, claims that it is a proven nootropic, anti-ageing therapy or “limitless pill” for healthy people are not supported by strong human evidence. Small and experimental studies exist, but they do not justify broad, unsupervised, daily use for cognitive enhancement or longevity at this stage.Third, self-experimenting with methylene blue, especially using non-medical products bought online, at doses not overseen by a doctor, and combined with other medicines such as SSRIs, carries real risk. As Anne-Sophie Fluri put it: “Without solid evidence in humans, these claims are at best speculative and at worst potentially dangerous.”In that sense, methylene blue sits at an uncomfortable crossroads between legitimate drug and wellness trend. For doctors, it is a narrow, specialist tool. For some celebrities and influencers, it has been framed as a shortcut to better thinking and slower ageing. For now, the science has not caught up with those promises.Anyone considering it is repeatedly advised by experts to speak to a qualified clinician first, particularly if they are taking antidepressants or other medications, and to remember that “going viral” is not the same as being proven safe or effective.
