Methylene Blue- USP Grade

Methylene blue is one of the ingredients where our naturopaths spend more time on who shouldn't take it than who should. Here's the triage they'd run, in the order they'd run it.

A good fit if

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

Check with us first if

• Taking any prescription medicine. European product information calls it a potent reversible inhibitor of monoamine oxidase, so interactions reach beyond antidepressants.
• Not knowing your G6PD status. The 2018 malaria trial tested every participant and excluded anyone with the deficiency before giving a single dose.
• 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: Hospital antidote for medicine- or chemical-induced methaemoglobinaemia, dosed by body weight.
• Imported oral drops, capsules or tinctures. Best known for: The form sold online as a nootropic. Unregistered, and 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. Not 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: Clinician-applied to skin, gums or mouth, then activated with a light source. It's not swallowed. Absorption: Local application 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 NRV, RDI, AI or EAR 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 lawful supplement range in Australia, because it can't be an ingredient in a listed medicine. Imported products carry doses 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 cognition trial used a single low oral dose, and its abstract doesn't say how many milligrams.

Upper level. European product information sets a maximum cumulative 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's studied that. Your needs depend on your age, diet and health circumstances. 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

This list is the part of the page we will not shorten. If any of it applies to you, talk to one of our naturopaths or your doctor before starting.

• Serotonergic medicines: SSRIs, SNRIs, MAOIs, some painkillers and opioids. Serotonin syndrome, potentially fatal. Absolute exclusion.
• Pregnancy. TGA: should not be used; associated with birth defects in humans and animals. Absolute exclusion.
• Breastfeeding. EMA: discontinue for up to 8 days after treatment.
• G6PD deficiency. Haemolysis risk; EMA contraindication. Status often unknown to the person.
• Hypersensitivity to methylene blue or other thiazine dyes. EMA contraindication.
• Children. Paediatric dosing exists only as a supervised hospital antidote protocol.
• Any prescription medicine. Potent reversible MAO inhibitor per EMA.
• Imported product users. Unregistered, contents and dose unverified, usually no instructions or warnings.
• If you take prescription medicines, check with your doctor, pharmacist or our naturopaths before starting.