Robert F. Kennedy, Jr. has a history of doubting vaccines and touting out-of-the-box (and often disproven) remedies—ivermectin, hydroxychloroquine, raw milk, and hyperbaric therapies among them.
The latest treatment to find itself attached to the Secretary of Health and Human Services is something called methylene blue, a Smurf-colored liquid embraced by influencers and biohackers for its alleged brain-boosting and longevity powers.
“Starting methylene blue; protocol and evidence rationale coming soon,” famous biohacker Bryan Johnson shared to X, along with a photo of the drug (in capsule version), in March.
Starting methylene blue; protocol and evidence rationale coming soon pic.twitter.com/facvQTqM8P
— Bryan Johnson (@bryan_johnson) March 3, 2025
That was shortly after Mel Gibson told Joe Rogan about how he had friends who cured their stage 4 cancer with a mixture of methylene blue, ivermectin, and other drugs—and also right after a video circulated of RFK Jr. putting a dropperful of bright blue liquid into his glass of water, leading many to assume it was methylene blue (something Kennedy has neither confirmed nor denied).
What is RFK Jr. putting in his drink…?? pic.twitter.com/R9ZXmwmfVC
— American AF 🇺🇸 (@iAnonPatriot) February 5, 2025
Since then, blue-tongued social media shoutouts to the mysterious indigo liquid—originally a fabric dye—have ramped up, including through nearly 10,000 hashtagged TikTok posts, where it gets called a “game changer” that’s “an antioxidant,” “neuroprotective,” and “brain-boosting.”
Below, all you need to know about the substance.
What is methylene blue?
Methylene blue—also known as Methylthioninium chloride and basic blue 9—is an organic chloride salt that was first synthesized in 1876 by Heinrich Caro at Germany’s BASF company for use as a textile dye. And, explains chemist Joe Schwarcz, director of McGill University’s Office of Science and Society and author of Quack Quack: The Threat of Pseudoscience, it’s made from petroleum—also, interestingly, the origin of the many artificial food dyes that Kennedy wants banned.
After its initial discovery as a good fabric dye, a doctor by the name of Paul Ehrlich became interested in the ability of certain dyes to stain microbes, to make them visible under the microscope. He discovered that methylene blue not only stained the parasite causing malaria but killed it. Although quinine was already being used as a malaria treatment, methylene blue is now “seeing a revival,” he noted in a recent column for the Montreal Gazette, due to the rise of treatment-resistant malaria.
Another function arose in the 1930s, when methylene blue was first used to detect the purity of milk, as sufficient oxygen is what makes the chemicals turn blue; it’s still used for that purpose today.
Is it FDA approved for anything?
Just last year, the U.S. Food and Drug Administration has approved methylene blue for use in the treatment of methemoglobinemia—a rare blood disorder, either genetic or caused by nitrates in medications or some recreational drugs, in which a person’s blood is not able to transport oxygen, thus turning the skin blue. The disorder can be reversed with methylene blue, which appears on the World Health Organization’s essential medicines list (EML), which is a register of minimum medicine needs for every health-care system. .
It’s also used to reverse cyanide poisoning, a life-threatening condition called vasoplegic syndrome (in which blood vessels lose their ability to constrict), and encephalopathy caused by some chemotherapies‚ according to the FDA, as well as by surgeons as a stain to guide them towards certain tissues, blood vessels, or lymph nodes.
What science says about methyl blue as a wellness trend
Biohacking influencers claim it is a nootropic, meaning it has positive effects on cognition, mood, and the function of mitochondria, which produce energy for cells and become less effective with age. That includes the author of The War on Ivermectin, Dr. Pierre Kory, who spoke of methylene blue as boosting “mitochondrial respiration,” in an interview with the RFK Jr.–founded Children’s Health Defense in 2022. (And, back in 2020, the FDA issued warnings to wellness centers offering it as an unapproved treatment for long COVID.)
While some studies have shown some promise in these areas, Kan Cao, PhD, an associate chair in the Department of Cell Biology and Molecular Genetics at the University of Maryland and creator of a skincare line containing methylene blue, told Health, they were predominantly done on animals, not humans.
“There is not solid data on how methylene blue would work off-label for something like cognitive function,” Jamie Alan, PharmD, PhD, a pharmacologist at Michigan State University, told Everyday Health. (A couple of clinical trials were carried out in the 1980s, and showed promise, but noted that more investigation was warranted.)
As far as it being an antioxidant, meaning it neutralizes damaging free radicals that accumulate in the body, Schwarcz says that is “incorrect.” It’s actually the colorless version of methylene blue—which is reacted with glucose rather than oxygen—that is “indeed an antioxidant,” although it’s not available, and would require doing “some chemistry.”
He adds that there have been “some interesting experiments with Alzheimer’s disease,” which is characterized by a type of protein that gets tangled in the brain. There is some evidence that methylene blue can untangle those proteins, he says, “but that’s only in the laboratory, in a test tube. No one has ever shown any benefit in human clinical studies.”
So while Schwarcz finds it a “mystery” as to how biohackers have latched onto the blue drug, he suspects some have read the studies. “And of course, they misinterpret it, and they take two plus two and make it equal to five.”
The risks of methylene blue
Again, while not much is known about risks because it’s not been studied, there are some known issues—electric-blue urine, for one, and possibilities including nausea, diarrhea, vomiting, gastritis, and jaundice, according to a News Medical Life Sciences article.
And there is one major known risk, according to an FDA warning from 2011, updated in 2017: that the drug can cause a life-threatening central nervous system reaction if given to someone already on SSRI antidepressants—which are taken by about 33 million Americans (13%).
“You develop what is called serotonin syndrome, and you don’t want to have that,” says Schwarcz, noting that it can cause agitation, increased heartbeat, hallucinations, and other unpleasant symptoms.
“So certainly, anyone who is taking SSRI should stay away from methylene blue,” he says. “But I think everyone should stay away from methylene blue, because there’s no reason to use it except in a medical setting.”
More on biohacking:
- Silicon Valley’s $7,500 a year biohacking clinic co-founded by Peter Attia is now betting on the wealthy elite of New York City
- Behind the scenes of this tech millionaire’s ‘Don’t Die’ summit as extreme biohacking becomes a dominant wellness trend
- Lebron James and Silicon Valley’s elite use hyperbaric oxygen therapy to stall aging and inflammation. Here’s what it’s all about
