A medical expert has issued an urgent warning to users of the so-called 'limitless pill'.
Masood Sahibzada, the founder of a rare disease research company, claims the drug - known as methylene blue - could trigger serious health issues for people with a common condition.
What is methylene blue?
Methylene blue is a synthetic dye used for treating malaria, cyanide poisoning, and especially methemoglobinemia, a rare blood disorder that affects oxygen delivery.
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Recently though, doctors have been sounding the alarm over using the 'brain juice', popularised by the likes of Joe Rogan and Robert F. Kennedy Jr.
Over on TikTok and Instagram, influencers are claiming that the substance can enhance focus, improve mood, memory and even slow down aging. It's nicknamed the 'limitless pill' in reference to 2011 film Limitless, where Bradley Cooper’s character takes a drug that dramatically boosts his brainpower.
But in reality, methylene blue is a dye which is usually mixed into a glass of water.
Side effects of the 'limitless pill'
The CEO of UAE-based MBL Health told LADbible that the 'hazard lies in a common genetic quirk', which around one in 15 people have worldwide.
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Those with G6PD deficiency - where the body doesn't produce enough of a protein called G6PD, which helps red blood cells work properly - could be at risk, he warns.
Sahibzada said that 'even a small amount of methylene blue can trigger the rapid breakdown of red blood cells, causing sudden anaemia, skin yellowing (jaundice), and strain on the kidneys'.
"That’s the opposite of feeling 'limitless," he added.
Other side effects of the 'limitless pill' include 'sudden weakness, lightheadedness and shortness of breath'.
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"Methylene blue is safe when doctors administer precise, low doses under medical supervision.
"However, people taking higher, unregulated amounts in hopes of sharper thinking can actually disrupt the way their blood carries oxygen," the expert warned.
The 'limitless pill' could be 'life-threatening'
Methylene blue could even be 'life threatening' for people taking a common antidepressant.
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"Things get riskier if someone is already taking antidepressants like SSRIs or SNRIs," Sahibzada said.
"Methylene blue acts like a monoamine oxidase inhibitor (MAOI), which can clash badly with those medications.
"Mixing the two can send serotonin levels soaring, leading to a potentially life-threatening reaction called serotonin syndrome, marked by high fever, shaking, and a racing heart."
In the UK, methylene blue is legal as a prescription medicine for methemoglobinemia, but off‑label usage hasn't been approved.
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"In short, methylene blue isn’t a harmless shortcut to peak performance. Its safe dosage window is narrow, it can interact dangerously with common medications, and the long-term effects remain unknown," he cautioned.
"Anyone considering it should discuss it with a healthcare professional first, especially to screen for blood conditions and review current prescriptions."
Anish Vij