Does methylene blue really have wellness benefits or will it just leave you with the blues? | Donna Lu

A week before he was sworn in as secretary of the US Department of Health and Human Services in February, a video of anti-vaccination conspiracy theorist Robert F Kennedy Jr went viral.

In it, Kennedy, who has frequently promoted debunked health claims, is seen dumping an inky blue liquid into a drinking glass. The substance has been widely speculated to be a dye called methylene blue, although Kennedy has not made public comments about it.

Fabric dye is also used by Joe Rogan – who, in a podcast a few weeks later, said that “RFK Jr told me about it” – and Bryan Johnson, the mud-eating American venture capitalist who has spent millions trying to prevent the (famously) inevitable process of dying.

So, what is methylene blue and is there any gold standard evidence that it is good for your health?

What is methylene blue?

Methylene blue is a synthetic textile dye, known for its ability to bond well to fabrics. (Kennedy, ironically, wants the American food industry to stop using artificial colors.)

The substance has gained popularity in wellness circles, with a long list of claimed benefits including that it boosts cognition, increases energy levels, has anti-aging effects, relieves stress, and has antioxidant effects. On TikTok, influencers stick out their blue tongues and put cobalt dye directly into their mouths.

But ingesting the dye for unauthorized purposes carries serious risks.

Methylene blue was first synthesized in the late 19th century. Dark green in powder form and dark blue when dissolved in water, this synthetic dye was quickly discovered to kill the parasite that causes malaria.

It became one of the first fully synthetic drugs used in medicine and was widely used during World War II, when quinine – the standard antimalarial treatment at the time – was in short supply.

“The troops were not impressed because their urine was turning blue,” says Dr Ian Musgrave, a molecular pharmacologist at the University of Adelaide. “This is one of the most commonly reported side effects of methylene blue, even today.”

Although it is now rarely used against malaria, methylene blue is considered an essential medicine by the World Health Organization. It is primarily used to treat methemoglobinemia, a blood disorder characterized by excess methemoglobin – a form of hemoglobin that cannot carry oxygen – in the blood.

Methylene blue has redox properties, meaning it can gain and give up electrons and, through a chemical reaction, returns hemoglobin to its functional form. It is also sometimes used to treat the effects of carbon monoxide and cyanide poisoning.

“I used methylene blue when I was studying biochemistry, because it’s one of the oldest dyes… for staining DNA and all sorts of biological molecules,” says Dr Slade Matthews, senior lecturer in pharmacology at the University of Sydney. “It has been used as a dye in surgery, but there have been many reports of toxicity.”

Does methylene blue have health benefits?

Much of the hype around methylene blue has its origins in studies carried out in animals as well as in vitro – on cells tested in the laboratory – and the Victorian Poisons Center warns: “There is currently no evidence that methylene blue improves brain health or function in healthy individuals. »

Methylene blue can enter the brain through a protective membrane called the blood-brain barrier. In rodents, studies suggest it can improve memory and prevent degeneration in conditions that mimic Alzheimer’s disease, but Musgrave notes that it has “largely failed in human clinical trials for the treatment of Alzheimer’s disease.”

As an antioxidant, he notes that “while there are promising results in tissue culture, there is currently no evidence in humans that it has significant anti-aging effects.”

Those selling methylene blue and other compounds marketed to boost brain function often make vague claims that are difficult to prove or disprove, Matthews says. “Proving that a drug is going to make you smarter is really difficult. That’s why they make such claims; they don’t say it produces an easily measurable effect.”

What are the health risks associated with methylene blue?

Across Australia, poison information centers have noted an increase in calls following the ingestion of methylene blue, with some patients developing significant symptoms.

The Western Australian Poison Information Center recorded nine calls this year, compared to one call per year in the previous two years. Centers in Queensland and Victoria have already received more calls this year (eight in both states) due to methylene blue exposure than the previous four years combined.

“Most of these exposures appear to be linked to the ingestion of methylene blue for unapproved wellness purposes,” says Carol Wylie, director of the Queensland Poisons Information Centre. “Consumption of unregistered or unapproved methylene blue may cause serious side effects, including nausea, vomiting, increased heart rate, dizziness, confusion, and skin discoloration.”

In September, the drug regulator issued a safety advisory, noting an increase in the importation and unregistered use of methylene blue, and warning that the dye may interact with drugs such as serotonin reuptake inhibitors (SSRIs), a common type of antidepressant.

Matthews has seen methylene blue sold online in doses that, in people taking SSRIs, can cause serotonin syndrome — a potentially fatal illness that can cause muscle spasms, confusion and agitation.

And despite its use as a treatment for methemoglobinemia, he points out that in high doses, the dye can paradoxically cause this disease.

In healthy people, it also frequently causes pain in the extremities, nausea, excessive sweating, and changes in taste and skin color.

Given the evidence, wellness influencers drink this dye at their peril — the rest of us should resign ourselves to pointing out its risks until we’re blue in the face.

• Donna Lu is deputy editor, climate, environment and science at Guardian Australia

• Antiviral is a biweekly column that interrogates the evidence behind health headlines and fact-checks popular wellness claims.