Methylene Blue Half-Life, Strengths & Approval Status
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Methylene Blue: half-life, strengths and approval status

Approved form · Approval status · Half-life ~24 hours

Short answer: Methylene blue has a half-life of about 24 hours. People vary, so treat these as estimates.

What is methylene blue?

Methylene blue is a blue dye that is also a drug. In the body it is converted to leucomethylene blue, which turns methemoglobin, a form of hemoglobin that cannot carry oxygen, back into normal hemoglobin.

Also known as: ProvayBlue.

Approved form

The FDA-approved product, ProvayBlue, is an injection for intravenous use at 5 mg/mL, in 2 mL (10 mg) and 10 mL (50 mg) ampules and vials. It is not approved for use by mouth.

Approval status and how it is used

The FDA ProvayBlue label approves methylene blue for acquired methemoglobinemia in children and adults, at 1 mg/kg given into a vein over 5 to 30 minutes, with one repeat dose after an hour if needed. Taking methylene blue by mouth, for example for energy or memory, is not an approved use.

The label's boxed warning says methylene blue can cause serious or fatal serotonin syndrome with SSRIs, SNRIs, MAO inhibitors and opioids, and advises not taking serotonergic drugs within 72 hours after the last dose; the label notes literature reports suggesting it is a potent reversible MAO inhibitor. It is contraindicated with G6PD deficiency because of severe hemolysis (red blood cell breakdown). It turns urine and skin blue and can throw off urine dipstick tests.

By mouth, a study in 16 healthy volunteers (Walter-Sack 2009) found an absolute bioavailability of about 72% for a single 500 mg dose of an oral solution compared with 50 mg into a vein. That is a study protocol, not a recommendation. If you take any antidepressant or opioid, ask your prescriber before using it.

Methylene blue half-life and time to peak

  • Half-lifeabout 24 hours
  • Time to peak (Tmax)Not listed

The FDA ProvayBlue label gives a half-life of about 24 hours, with about 40% excreted unchanged in urine. Exposure rises with kidney impairment: after 1 mg/kg, total exposure (AUC) was 52%, 116% and 192% higher with mild, moderate and severe impairment. The label covers intravenous use, so there is no time to peak by mouth to list.

Numbers shown are taken from the source above. Half-life varies from person to person.

How to track methylene blue in Dose Track

  1. Add methylene blue as a custom compound. Start typing its name and Dose Track fills in the details from its research library for you to check, and it sits next to everything else you take.
  2. Log each dose when you take it so your history shows exactly what you took and when.
  3. Set reminders on your own schedule, whether that is daily, weekly or every few days.
  4. Your log is stored on your phone and no account is needed. Data only leaves it for features you choose, like AI answers and lab reading.

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Frequently asked questions

What is the half-life of methylene blue?+
The FDA ProvayBlue label gives a half-life of about 24 hours, with about 40% excreted unchanged in urine. Exposure rises with kidney impairment: after 1 mg/kg, total exposure (AUC) was 52%, 116% and 192% higher with mild, moderate and severe impairment. The label covers intravenous use, so there is no time to peak by mouth to list.
Can methylene blue be taken with antidepressants?+
The FDA ProvayBlue label has a boxed warning against it: methylene blue can cause serious or fatal serotonin syndrome with SSRIs, SNRIs, MAO inhibitors and opioids. The label advises not taking serotonergic drugs within 72 hours after the last dose.
Can I track methylene blue in Dose Track?+
Yes. Methylene blue is in Dose Track's research library, so when you add it as a custom compound its details are filled in for you to check. You can then log each dose next to your other compounds, set reminders on your own schedule, and see your history next to your lab results. Your log is stored on your phone and no account is needed. Data only leaves it for features you choose, like AI answers and lab reading.

Sources

  1. ProvayBlue (methylene blue) injection prescribing information, boxed warning and sections 1, 2, 3, 4, 5 and 12. DailyMed, June 2025.
  2. Walter-Sack I, et al. High absolute bioavailability of methylene blue given as an aqueous oral formulation. Eur J Clin Pharmacol. 2009;65(2):179-189.

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