Methylene Blue

With methylene blue, our naturopaths spend more time on who shouldn't take it than who should. These are the questions they ask, in the order they ask them.

A good fit if

• A doctor has prescribed it, or you're being given it in hospital
• You want an honest picture of the evidence before you decide anything
• You came in for focus or memory and you're open to a legal, better-studied option

Check with us first if

• You take any prescription medicine. European product information calls it a strong, reversible blocker of monoamine oxidase, so the interactions go beyond antidepressants.
• You don't know your G6PD status. The 2018 malaria trial tested every participant and left out anyone with the deficiency before giving a single dose.
• You're already using an imported product. Tell your GP or pharmacist what you're taking and how much, especially if you take other medicines.

• Methylthioninium chloride injection. Best known for: The only lawful medicinal methylene blue in Australia. It's prescription-only when presented for injection, and given by a clinician. Absorption: Given into a vein, so absorption isn't the question. Typical use: A hospital antidote for methaemoglobinaemia caused by a medicine or chemical, dosed by body weight.
• Imported oral drops, capsules or tinctures. Best known for: The form sold online as a nootropic. It's unregistered, and it's the form the TGA's September 2025 advisory is about. Absorption: It's absorbed when swallowed, but the dose and contents of these products aren't verified. Typical use: No approved use. It isn't lawful to supply as a supplement in Australia.
• Laboratory, aquarium or industrial dye. Best known for: Staining microscope slides and treating fish tanks. Not made to medicine standards. Absorption: Not applicable. Typical use: Never for human use.
• Topical photosensitiser, 0.1% to 1%. Best known for: Applied by a clinician to the skin, gums or mouth, then activated with a light. It's not swallowed. Absorption: Applied locally only. Typical use: Studied in dental and scar clinics. None of that evidence applies to taking it by mouth.

Reference values. There's no Australian recommended intake for methylene blue. It's a synthetic dye, not a nutrient, so your body has no dietary need for it.

Typical supplemental range. There's no legal supplement range in Australia, because it can't be an ingredient in a listed medicine. Imported products carry whatever dose the seller chose. The medical doses are hospital doses: 1 to 2 mg per kg of body weight, injected over five minutes, for methaemoglobinaemia. The one small trial on thinking and memory used a single low oral dose, and its summary doesn't say how many milligrams.

Upper level. European product information sets a maximum total dose of 7 mg per kg, or 4 mg per kg in some cases. Above 7 mg per kg, it can cause the very blood problem it's meant to treat. The only high-dose oral trial used 15 mg per kg a day for three days, roughly 1,000 mg for a 70 kg adult, and it screened out anyone with G6PD deficiency first.

Worth knowing. Every dose in the research was given or supervised by a doctor, mostly into a vein. None of it tells you how much to take at home, because nobody has studied that. What you need depends on your age, diet and health, so talk to one of our naturopaths.

Food first, where the diet allows it.

• No food: it doesn't occur in food and isn't a nutrient. It's a synthetic dye

If any of these sound like you, talk to one of our naturopaths or your doctor before you start.

• Serotonergic medicines: SSRIs, SNRIs, MAOIs, some painkillers and opioids. Together they can cause serotonin syndrome, which is potentially fatal. Never take it with these.
• Pregnancy. The TGA says it should not be used; it's associated with birth defects in humans and animals. Never take it while pregnant.
• Breastfeeding. The EMA advises stopping breastfeeding for up to 8 days after treatment.
• G6PD deficiency. It risks breaking down red blood cells (haemolysis), and the EMA lists this as a contraindication. Many people don't know they have it.
• Sensitivity to methylene blue or other thiazine dyes. The EMA lists this as a contraindication.
• Children. Dosing for children exists only as a supervised hospital antidote protocol.
• Any prescription medicine. The EMA describes it as a potent reversible MAO inhibitor.
• Imported products. They're unregistered, their contents and dose are unverified, and they usually come with no instructions or warnings.
• If you take prescription medicines, check with your doctor, pharmacist or our naturopaths before you start.