The internet has been buzzing with discussions around a liquid chemical known as methylene blue, which is currently marketed as a health supplement.
In the last five to ten years, this chemical has gained attention online as a nootropic agent—a substance that purportedly boosts cognitive function. Various vendors assert that it enhances brain energy, improves memory, increases focus, and even clears away brain fog, among other claimed advantages.
Health influencers, including podcaster Joe Rogan, have promoted its benefits. In February 2025, just before his appointment as health and human services secretary, Robert F. Kennedy Jr. appeared in a video pouring a blue liquid, widely thought to be methylene blue, into a glass, although he never explicitly endorsed it.
As a researcher specializing in inflammation and cancer, I delve into how dyes might influence human health. The claims surrounding methylene blue sound enticing, making it simple to get caught up in its allure.
However, evidence backing its health claims remains minimal, and there are significant risks associated with using the substance outside of a medical context.
What is methylene blue?
Methylene blue is a synthetic dye that appears as a dark green powder, turning a deep blue when mixed with water. My research, along with that of others, indicates that many synthetic dyes prevalent in foods and medications can potentially trigger harmful immune reactions in our bodies.
Unlike commonly used food dyes—one of which was recently banned by the FDA—methylene blue isn’t derived from petroleum. Instead, it belongs to a different category of dyes thought not to carry similar health risks.
First created in 1876 as a textile dye, methylene blue was valued for its vibrant color and strong adherence to fabrics. Shortly after, German doctor Paul Ehrlich recognized its ability to stain biological tissues and kill the parasite responsible for malaria, making it one of the earliest synthetic drugs used in medicine.
Although methylene blue wasn’t widely adopted as a malaria treatment due to its effectiveness being on par with quinine, it found a new purpose in the 1930s for testing the safety of raw milk. If the blue color faded rapidly, the milk indicated bacterial contamination; if it remained blue, it was considered clean.
This safety test is now largely outdated, but it functioned because of methylene blue’s unique chemical properties, allowing its molecules to exchange electrons, much like a small battery charger.
How do doctors use it today?
This same chemical property enables several medical applications of methylene blue. Most notably, it’s used to treat a rare blood condition called methemoglobinemia, where hemoglobin, the iron-rich protein in red blood cells responsible for oxygen transport, transforms into a form that can’t perform its function.
Methylene blue helps restore hemoglobin’s function by transferring an electron.
In some cases, doctors also use it to treat the consequences of carbon monoxide poisoning, septic shock, or toxicities from chemotherapy drugs. Furthermore, it’s utilized as a surgical dye to highlight specific tissues, such as lymph nodes, or to detect damaged or leaky tissue.
How does methylene blue affect the brain?
Methylene blue has the ability to cross the protective barrier that encloses the brain. Researchers have also discovered that it can protect and support mitochondria, which are often referred to as the cell’s powerhouses.
Methylene blue may assist mitochondria in generating energy for cellular use. Consequently, researchers are investigating the chemical’s effects on brain function.
Currently, much of the knowledge regarding its brain impacts is based on studies involving rats and cells grown in laboratory conditions—not in humans. For instance, it’s been found that methylene blue may enhance learning, boost memory, and protect brain cells in rats simulating Alzheimer’s disease development.
Animal studies have further indicated that methylene blue can shield the brain from damage caused by injuries. Other research has shown its effectiveness in treating ischemic strokes in rats, though no studies have yet confirmed its benefits for human traumatic brain injuries or strokes.
Several clinical trials have explored methylene blue’s potential in addressing aspects of Alzheimer’s disease in people, but a 2023 review indicated that results have been mixed and inconclusive.
A small study involving 26 participants found that a single low dose of methylene blue boosted memory by about seven percent and increased brain activity during cognitive tasks. Another study by the same team noted changes in brain connectivity, though it did not enhance thinking skills.
While a few studies hint that methylene blue could be beneficial for certain brain-related conditions, such as pain control and neuropsychiatric disorders, these investigations have been limited. This suggests that although there may be scenarios where methylene blue proves useful, researchers haven’t clearly identified what those situations are.
Is methylene blue safe?
Methylene blue is generally safe when administered under medical supervision, but it carries some serious risks.
For instance, it can interact with commonly prescribed medications. Methylene blue inhibits an enzyme called monoamine oxidase, which breaks down serotonin, an essential brain chemical.
Many anxiety and depression treatments target serotonin. Combining the supplement with these medications could lead to serotonin syndrome, which manifests as agitation, confusion, elevated fever, rapid heart rate, muscle stiffness, and, in more severe cases, seizures or death.
For individuals with a rare genetic deficiency of an enzyme called G6PD, methylene blue can trigger a dangerous condition where red blood cells are destroyed too quickly. Additionally, at high doses, this chemical may increase blood pressure or cause heart issues. It’s also deemed unsafe for pregnant or breastfeeding women, as it might harm the fetus or infant.
In summary, although there’s been some intriguing research on methylene blue’s properties, much larger, longer-term studies are necessary to truly determine its efficacy, appropriate dosing, and safety over time.
