US company Troscriptions claims the product can boost energy levels, enhance memory, improve focus, and "protect the brain".
Such benefits have however been labelled highly optimistic by scientists, who say methylene blue has its place in lab work, but not so much medical treatment.
The potency of its colour makes it useful as a staining agent when working with cells, but is known to create huge messes when spilled.
"I remember a fellow grad student accidentally smashing a bottle of this stuff in the lab late one night. Worst mess I've ever seen. Her mouth, eyes etc went blue and for months afterwards, everything would start to turn blue every time the benches got wet," Saunders recalled.
US fitness influencer Ben Greenfield spruiked the product in a Facebook post last month, telling followers the reason for his blue tongue.
"It's methylene blue, a potent cognitive enhancer — albeit one that will turn your mouth – okay I'll say it – 'Smurf blue' for hours. This is one of my favourite nootropics due to its wide-ranging benefits," he wrote.
Californian professional runner Jordan Hasay posted about it this week, claiming methylene blue "can help to improve focus, endurance and sleep".
Methylene blue, when consumed in small doses, is harmless, however experts have argued its risks far outweigh any benefits, dismissing claims it acts as a "mitochondrial optimiser".
According to a research paper published by the Journal of Anaesthesiology and Clinical Pharmacology, the chemical can cause toxicity in high doses.
Features of toxicity include cardiac arrhythmias, coronary vasoconstriction, decreased cardiac output, renal blood flow and mesenteric blood flow; increased pulmonary vascular pressure and pulmonary vascular resistance, and gas exchange deterioration.
It can also turns urine a greenish blue colour, and cause a bluish discolouration of the skin.
In people who take SSRI antidepressants, methylene blue can cause serotonin toxicity because of how it reacts with the chemicals.
It also interacts with dapsone and forms hydroxylamine which oxidises haemoglobin causing haemolysis.
Many argued influencers would have the same luck with methylene blue as they would with blue food colouring when it came to tricking their mitochondria.
"I can do the same thing with a blue zooper dooper, and get no side effects," one person tweeted.
Someone else described the supposed health treatment "peak stupid".
