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Regulator warning Checked · 2 min · 1 sources

Methylene blue: the TGA's warning about a viral "nootropic"

A hospital drug turned social-media nootropic. In September 2025 the TGA warned Australians not to take oral methylene blue unless a health professional prescribes it.

Methylene blue is a blue dye with a long medical history; in hospitals it is given by injection for a few specific conditions. Online it has become a "nootropic", sold as drops and capsules said to sharpen focus, lift mood and slow ageing. Australians search for it 22,200 times a month.

What the TGA said

On 25 September 2025 the Therapeutic Goods Administration published a safety advisory about the growing importation of unregistered oral methylene blue products. It said these products were being promoted for unapproved uses such as cognitive enhancement, mood and anti-ageing, and had not been assessed for quality, safety or efficacy. Most products bought online, it said, carry no clear instructions or warnings.

The TGA's advice to consumers: do not use oral methylene blue products unless advised or prescribed by a healthcare professional.

The risks the TGA named

  • Serotonin syndrome. Taken with medicines that raise serotonin, including SSRI antidepressants and some painkillers, methylene blue can cause serotonin syndrome, which is potentially life-threatening. Symptoms include muscle spasms, sweating, tremor, confusion and agitation.
  • Pregnancy. It should not be used in pregnancy; it has been linked to birth defects in humans and animals.
  • G6PD deficiency. In people with this inherited condition it can damage red blood cells.

Yes, but

The TGA notes that methylene blue is prescription-only only when presented for injection. Oral products are not, but in the TGA's words they are "not without significant risks when used orally".

When to talk to your GP

Before taking it at all, and urgently if you take an antidepressant and have taken methylene blue.

Sources

  1. Imported unregistered methylene blue products, TGA safety advisory, 25 September 2025

Last checked 3 October 2026. Corrections are welcome: details on the about page.

General information, not medical advice. Check with your GP first, especially if you are pregnant, have a heart condition or take medication.

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