Welcome to the dark side

In Part 1 of this mini-series, I discussed the medical applications for which methylene blue is an approved, generally accepted or widely used treatment. You might recall that most of these applications are for conditions that are serious and even life-threatening, such as methemoglobinaemia, vasodilatory shock, malaria, and treatment of encephalopathy (brain dysfunction) induced by the cancer chemotherapy drug, ifosfamide. As I pointed out in Part 1, if you have a condition that is likely to kill you or inflict life-impairing harm on you, you might be open to trying a treatment that carries some risks of its own.

But ‘wellness influencers’ aren’t promoting methylene blue as a treatment for malaria or septic shock. Prominent biohackers interviewed for a New York Post article on methylene blue gushed about its ability to enhance “mental clarity” and “brain power”, “boost energy and metabolism”, and – I kid you not – help you swim under water for longer. Yeah, that last one has always been at the top of my list of health goals. The Post article also mentioned preliminary research suggesting methylene blue may delay skin aging.

So, should you take methylene blue to help you solve your first world problems like wrinkly skin and brain fag? Before you make that decision, let’s take a look at the dark side of the biohackers’ shiny new blue thing.

Adverse effects

The most well-known side effect of methylene blue is striking but reportedly benign: it turns urine, skin and mucous membranes blue-green. And because it readily crosses the blood-brain barrier and is then selectively trapped in the brain, where it rapidly reaches concentrations 10-20 times higher than in the blood, it stains the brain blue, too, as doctors conducting autopsies have documented:

Likewise, methylene blue is avidly taken up by red blood cells, perhaps explaining why it can also stain the heart “pistachio blue”:

(Thanks to Geoff Pain for alerting me to this phenomenon.)

Pathologists consider this discolouration to be a harmless side-effect of treatment with methylene blue, which is only of concern because if it’s not recognised, unnecessary postmortem toxicological testing might be performed.

Yet it’s well known that methylene blue disrupts communication between neurons in the brain and peripheral nervous system, affecting every major neurotransmitter system: acetylcholine, the monoamines (serotonin, dopamine, adrenaline/epinephrine and noradrenaline/norepinephrine) and glutamate. It both increases the release of neurotransmitters and inhibits their breakdown and removal. And it inhibits the enzymes that produce nitric oxide, a signalling molecule that plays crucial roles in cardiovascular function, including regulating blood pressure, heart muscle activity, and blood vessel tone; and protecting blood vessels against thrombosis (blood clot) formation and atherosclerosis. Hence, it strikes me as rather cavalier to dismiss the potential role of methylene blue in causing the demise of the unfortunate patient whose blue heart and brain ended up memorialised as a medical curiosity in a pathology journal.

After all, in high doses or when administered too rapidly, methylene blue can induce cardiac arrhythmia (abnormal heart rhythms). Other cardiovascular and cardiorespiratory complications include coronary vasoconstriction, decreased cardiac output (volume of blood pumped out by the heart), hypotension (low blood pressure), diminished blood flow to the kidneys and mesentery (the organ that attaches the intestines to the abdominal wall), increased pulmonary vascular pressure and pulmonary vascular resistance, and gas exchange deterioration.

And its monoamine oxidase (MAO) inhibiting activity can induce serotonin syndrome in people who take antidepressants in the serotonin reuptake inhibitor and MAOI classes. Serotonin syndrome is a potentially life-threatening consequence of drug-induced excess serotonin accumulation, with symptoms ranging from agitation and diarrhoea, to high fever and seizures. Medical journals are littered with case studies of patients who developed serotonin syndrome when doctors added methylene blue to their treatment regimen, including this one – a woman treated with methylene blue for ifosfamide-induced neurotoxicity.

Speaking of interactions between methylene blue and other pharmaceuticals, Drugs.com lists 198 of them, with 129 ranked as major, 67 as moderate, and 2 as minor. Among the drugs with major interactions with methylene blue (besides all the MAOI, SSRI, SNRI and atypical antidepressants) are Adderall (a medication prescribed for so-called ADHD), codeine (a very widely-used pain medication), eletriptan, naratriptan and sumatriptan (anti-migraine drugs), levodopa and selegiline (Parkinson’s medications), metaraminol (used to treat hypotension, especially as a complication of anaesthesia), and dolasetron and ondansetron (antinausea medications often given to cancer patients undergoing radio- and chemotherapy).

I wonder how many cancer and Parkinson’s patients started taking methylene blue after hearing a ‘wellness influencer’ spruik its benefits, and then ended up in hospital – or the morgue – with a serious drug interaction? Well, Geoff Pain left this comment on Part 1…

… which sent me off to check the US FDA Adverse Event Reporting System (FAERS). As of the date of writing this article (19 December 2025), there have been 1414 reports of adverse events involving methylene blue, and 195 of these have resulted in the death of the patient. That is, 13.8 per cent of reported adverse events involving methylene blue led to death. For comparison, Vioxx, Merck’s anti-inflammatory drug that was pulled from the market in 2004 after it was found to cause heart attacks, strokes and death – as senior company officials well knew before it was released onto the market – racked up 6633 deaths out of 64397 reported cases (a 10.3 per cent case fatality rate). It’s perhaps not a fair comparison, because Vioxx was marketed simply as a painkiller, whereas methylene blue is often used in serious situations with a high probability of death.

Nevertheless, adverse event reports involving methylene blue have surged in the last few years:

And, as Geoff noted, examination of case reports shows that the case fatality rates are accelerating. Is the widespread promotion of methylene blue encouraging both doctors and patients to use it for conditions for which there’s no convincing evidence of benefit? It appears so: the phrases “Product Used For Unknown Indication”, “Off Label Use”, “Product Use In Unapproved Indication” and “Drug Ineffective For Unapproved Indication” appear in case reports of deaths involving methylene blue with increasing frequency from around 2022-2023.

Methylene blue can cause methemoglobinemia – the condition for which it’s an FDA-approved treatment – when taking in high doses or ineffectively metabolised. High doses can also cause haemolysis (rupturing of red blood cells) and haemolytic anaemia, especially in people with glucose-6-phosphate dehydrogenase (G6PD) deficiency, the world’s most common inherited enzyme deficiency. G6PD deficiency causes red blood cells to break down more easily when exposed to triggers such as certain foods, viruses or medications, leading to anaemia and jaundice. It is more prevalent in males from South Asian, sub-Saharan African, Mediterranean and Middle Eastern backgrounds.

Use of methylene blue during breast cancer surgery and sentinel node biopsy has been reported to cause necrosis (cell death) in the skin, breast and fat tissue.

Other reported toxic effects include nausea, vomiting, abdominal pain, chest pain, headache, fever, sweating, dizziness, and confusion. Multiple cases of immediate allergic hypersensitivity, or anaphylactic, reactions to methylene blue have been reported; see Geoff Pain’s article Methylene Blue IgE Diseases for a detailed discussion.

And methylene blue should never be taken by pregnant women, or women intending pregnancy. The FDA designates it a pregnancy category X drug, meaning that human studies have shown concrete evidence of foetal harm. When taken in the second trimester of pregnancy, it has been associated with a high rate of foetal intestinal atresia, a birth defect that result in a blockage in either the small or large intestine after the baby is born. In a retrospective study of women with twin pregnancies who were administered methylene blue during amniocentesis, “fetal death occurred in 31·8 per cent of pregnancies that had exposure to a high concentration of methylene blue, compared with 14·5 per cent of pregnancies exposed to a low concentration and 4·3 per cent of pregnancies with no exposure to dye”. And in animal studies, offspring of mothers administered methylene blue have an increased incidence of cleft palate, digit malformations, and neural tube malformations.

Newborns are also highly susceptible to toxicity from methylene blue, and can suffer hyperbilirubinemia, meth-Haemoglobin formation, haemolytic anemia, respiratory distress, pulmonary oedema and phototoxicity (a drug-induced skin sensitivity to light) that can lead to skin desquamation– that’s where the top layer of skin peels off.

But what about that mental clarity?

When researchers studied the effects of methylene blue on cerebral blood flow and metabolism in healthy and cognitively normal women (i.e. not patients with Alzheimer’s disease), at doses typical of those used for other clinical applications, they were surprised to find that it decreased blood flow into the brain by 8 per cent, and also impaired brain oxygen utilisation in a dose-dependent fashion:

Huh, that’s weird. How are these findings to be reconciled with biohackers’ reports that methylene blue enhances cognitive capacity and focus? Psychiatrist Peter Breggin coined the term intoxication anosognosia, or in lay terms, ‘medication spellbinding’, to describe patients’ inability to recognise the deficits in their emotional and mental function that are induced by psychiatric drugs, when taken at normal, (supposedly) effective doses. That is, when people are taking psychiatric drugs, they may believe that the drug is making them feel better and think more clearly and creatively, but what their loved ones observe is that they’re emotionally blunted, or manic, or engaging in compulsive behaviours, or robotic in their responses.

According to Breggin,

“Medication spellbinding applies to all psychoactive substances, both medical and non-medical, and helps to explain why people continue to take harmful drugs.”

Emergency notification: methylene blue is highly neurotoxic to your brain and mind

As mentioned above, methylene blue increases the release, and via its inhibition of monoamine oxidase (MAO), prevents the breakdown, of the monoamine neurotransmitters serotonin, dopamine, adrenaline/epinephine and noradrenaline/norepinephrine. The predictable effect is hyperactivation of these monoamine neurotransmitters. And as Breggin points out, there are multiple drugs that also cause this monoamine hyperactivation, and all of them are characterised as stimulants: cocaine, methamphetamine, and the drugs marketed for treatment of so-called ADHD -methylphenidate (Ritalin, Focalin), and amphetamine/dextroamphetamine (Adderall). Do kids pay more attention in class when they take Ritalin? Yes, they do (although they don’t actually learn their lessons any better than unmedicated kids). Do people feel awesome when they take cocaine? Apparently so; ask any dealer about their repeat business. So should we take people at their word when they say that methylene blue has enhanced their cognitive capacity? Only if you believe this guy when he tells you he functions better after a bump.

Methylene blue and the commodification of ‘wellness’

In his 2003 book Better Than Well: American Medicine Meets the American Dream, Carl Elliott explored the interaction between two defining characteristics of his countrymen: an obsession with self-improvement, and the embrace of free market solutions to all one’s problems. Good old American entrepreneurialism eagerly steps in both to meet the population’s demand for ‘enhancement technologies’, and to ramp up that demand by creating marketing campaigns that recast completely normal human experiences, such as feeling sad, finding it hard to focus on boring things, or developing wrinkles, as problems to be solved… conveniently, by the product behind the marketing campaign.

As I wrote in Drugging ourselves to health?,

“The medical model conceptualises the human body as a sack of organs and body fluids that, throughout the course of life, inevitably malfunctions in various ways, either because it is attacked by germs, or deranged by disease-causing genes, or aging, or just bad luck (which is euphemistically dubbed idiopathic, a fancy-schmancy word for ‘we don’t know what caused your illness and, truth be told, have little interest in finding out’).”

Drugging ourselves to health?

Naturally, if you believe that illness is the result of some malfunction in the body, your approach to treatment will be to use drugs and procedures that interfere with the biological pathways that lead to the signs and symptoms by which the illness becomes manifest.

“By contrast, traditional healing practices conceptualise health as our normal and natural state, which is engendered by the provision of the requirements of health: clean air, pure water, species-appropriate diet, physical activity, rest and sleep, exposure to sunlight and nature, secure attachments to loved ones and satisfying social interactions, and engagement in productive activity that provides a sense of purpose and meaning. Note that each of these requirements of health has an optimal quantity, which varies depending on the individual’s life stage and current vitality level, and that too much of any of these factors (except clean air) can be as bad for our health as too little.

If a person becomes ill, it’s safe to assume that one or more of the requirements of health are not being supplied in appropriate quantities and proportions, and/or causes of disease (such as compounds which are foreign to our bodies) have been introduced. It logically follows that a rational approach to treatment of illness would be to remove the cause/s of disease, and to ensure that each requirement of health is being supplied in its currently-appropriate quantity.”

Drugging ourselves to health?

The ‘health freedom movement’, for want of a better term, has become intensely sceptical of pharmaceutical companies, and the doctors who mostly seem to act as their sales agents. That’s fine by me; it’s about time. But the danger I see is that many of these people are quitting their drugs, only to replace them with nutritional supplements and off-label pharmaceuticals such as methylene blue and DMSO.

While there are definitely some cases where supplements and even pharmaceuticals are necessary, they should always be thought of as add-ons to the core treatment plan, which is, and must always be, removing the causes of disease, and ensuring that all the requirements for health are being supplied in the currently-appropriate quantity.

I urge you to reject the commodification of your health that both Big Pharma and the wellness industry promote. As I never tire of repeating to my clients (though they might tire of hearing it from me!), health comes from healthful living.

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