# Methylene blue

Methylene blue is FDA-approved as a drip into a vein for a rare blood disorder. No approval covers memory or mood, where the evidence grade is limited-human: a few small trials. It can cause a deadly reaction with some antidepressants.

Status checked: 2026-10-26. Last verified: 2026-10-26. Primary source: https://www.accessdata.fda.gov/scripts/cder/daf/index.cfm?event=overview.process&ApplNo=204630

This page has not been individually reviewed by a clinician.

Information, not medical advice.

| Fact | Value | Tier | Checked | Source |
|---|---|---|---|---|
| Also called | methylthionium chloride | peer-reviewed | 2026-10-26 | [source](https://pubmed.ncbi.nlm.nih.gov/17721552/) |
| Class | non-peptide | primary | 2026-10-26 | [source](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=4f6848e5-35ed-4046-b13c-3032b5ba3232) |
| Regulatory status | fda-approved | primary | 2026-10-26 | [source](https://www.accessdata.fda.gov/scripts/cder/daf/index.cfm?event=overview.process&ApplNo=204630) |
| Status source read | 2026-10-26 | primary | 2026-10-26 | [source](https://www.accessdata.fda.gov/scripts/cder/daf/index.cfm?event=overview.process&ApplNo=204630) |
| Evidence grade | limited-human | our assessment | 2026-10-26 | [source](https://peptideindex.ai/methodology#evidence-grade) |
| Label dosing | From the ProvayBlue label. It is given by drip into a vein over 5 to 30 minutes, at 1 mg per kilogram of body weight. If the blood level stays above 30% or symptoms persist, one more dose of up to 1 mg per kilogram may be given an hour later. People with moderate or severe kidney disease get a single dose. The prescriber sets the dose. | primary | 2026-10-26 | [source](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=4f6848e5-35ed-4046-b13c-3032b5ba3232) |

## Name

Methylene blue

Source: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=4f6848e5-35ed-4046-b13c-3032b5ba3232

## Summary

A blue dye that is a prescription drug for a rare blood disorder. Drops of it are also promoted online for brain health.

Source: https://www.npr.org/2025/12/15/nx-s1-5634680/methylene-blue-supplement-safety

## Short answer

Methylene blue is FDA-approved as a drip into a vein for a rare blood disorder. No approval covers memory or mood, where the evidence grade is limited-human: a few small trials. It can cause a deadly reaction with some antidepressants.

Source: https://peptideindex.ai/methodology#short-answer

## Known risks

- The label carries a boxed warning. Methylene blue can cause serotonin syndrome, which can kill, when used with some antidepressants or with opioids [^2].
- Methylene blue strongly blocks MAO A, an enzyme. An enzyme study says this may be why it can cause serotonin toxicity in people who take some antidepressants [^10].
- People with G6PD deficiency, an inherited red blood cell problem, can have their red blood cells break down. The label says they must not get it [^2] [^13] [^17].
- Some people have had serious allergic reactions [^2].
- It may harm an unborn baby, the label says [^2].
- It can cause confusion, dizziness and trouble seeing. The label advises against driving until these pass [^2].
- In the label's study, the most common problems were headache, diarrhea, nausea and muscle jerks. Low potassium, low magnesium and seizure-like events were on the list too [^2].
- It can make a finger oxygen monitor read too low. It also turns urine blue [^2] [^17].

Source: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=4f6848e5-35ed-4046-b13c-3032b5ba3232

## What nobody knows yet

- Nobody knows if methylene blue by mouth helps memory over time. The 2016 brain scan trial tested one dose in 26 healthy adults [^8].
- The bipolar trial found less depression and anxiety in 37 people who also took another drug [^9]. Nobody knows if it helps others with depression.
- In septic shock, the 2024 review rated its evidence as low certainty and called for better trials [^11].
- Experts quoted by NPR in 2025 called the human findings for brain health early [^17].
- Buyers online may not know what is in the bottle. An expert quoted by NPR said oversight of supplements is weak [^17].
- A mouse study after brain injury does not show that it helps healthy people think better [^12].

Source: https://pubmed.ncbi.nlm.nih.gov/27351678/

## What it is

Methylene blue is a blue dye that is also a medicine. It has been used in medicine for centuries [^14]. It is not a peptide.

The approved drug is ProvayBlue, a liquid given by drip into a vein [^1] [^2]. It treats acquired methemoglobinemia, a rare blood disorder [^2] [^17]. The dye also strongly blocks MAO A, an enzyme that acts on serotonin [^10].

Online, drops of it are promoted for brain health and long life [^17]. Its color can stain the tongue and urine blue [^17].

Source: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=4f6848e5-35ed-4046-b13c-3032b5ba3232

## Where it stands legally

Methylene blue is FDA-approved: Drugs@FDA lists ProvayBlue, a prescription drug given by drip into a vein, as an approved drug [^1]. That approval covers one use, acquired methemoglobinemia in children and adults [^2]. It does not cover pills or drops taken by mouth for memory, mood or energy. Checked 26 October 2026.

In June 2020, FDA sent warning letters about methylene blue products sold online with COVID-19 claims [^6] [^7]. FDA called them unapproved new drugs and misbranded drugs [^6] [^7]. A news report says it is not clear that methylene blue can be sold as a dietary supplement [^17].

Pharmacies may compound with a raw substance that meets a USP standard or is part of an FDA-approved drug [^3]. Methylene blue is the active part of ProvayBlue [^1]. It is not on FDA's 503A category list [^4]. Compounded drugs are not FDA-approved, and FDA has not reviewed them before sale [^5]. A pharmacy may not regularly make copies of a drug that is on the market [^5].

Source: https://www.accessdata.fda.gov/scripts/cder/daf/index.cfm?event=overview.process&ApplNo=204630

## What the evidence shows

The evidence grade is limited-human: for memory and mood, there are only a few small trials in people [^8] [^9]. In a 2016 trial, 26 healthy adults took one low dose by mouth or a dummy pill [^8]. An hour later, brain scans showed more activity during memory tasks [^8]. Correct answers on one memory test rose by 7% [^8].

In a 2017 trial, 37 people with bipolar disorder took it beside their usual drug [^9]. It eased leftover depression and anxiety. It did not help thinking skills [^9].

For its approved use, the label reports 31 adults with acquired methemoglobinemia [^2]. In 26 of 28 people with a level measured before treatment, the level fell by half or more [^2]. In septic shock, a 2024 review of six trials with 302 patients found it may lower early deaths [^11]. The review rated that evidence as low certainty [^11].

Much of the brain story comes from animals. In mice with a brain injury, it partly kept memory from getting worse [^12]. That does not show it helps healthy people.

Source: https://pubmed.ncbi.nlm.nih.gov/27351678/

## Legitimate ways to get it

The legal way to get methylene blue is ProvayBlue, a prescription drug given by drip into a vein [^1] [^2]. It is approved for acquired methemoglobinemia in children and adults [^2].

Pharmacies may compound with a raw substance that meets a USP standard or is part of an FDA-approved drug [^3]. A compounded product is not FDA-approved [^5].

Two US trials of methylene blue for memory have finished [^15] [^16]. The trials block on this page lists open trials with their dates.

Source: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=4f6848e5-35ed-4046-b13c-3032b5ba3232

## How people are getting it anyway

This section describes what happens and is not a recommendation.

Drops of methylene blue are promoted online for brain health and long life [^17]. Many of these products are not labeled as dietary supplements [^17].

In June 2020, FDA and the Federal Trade Commission sent warning letters to two wellness centers [^6] [^7]. Each sold methylene blue products online with claims about COVID-19. FDA called the products unapproved new drugs and misbranded drugs [^6] [^7]. FDA told consumers not to buy or use such products [^6].

Source: https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/north-isle-wellness-center-607947-06192020

## Access routes

Source: https://www.accessdata.fda.gov/scripts/cder/daf/index.cfm?event=overview.process&ApplNo=204630

### Approved product

Detail: Approved by FDA as a prescription drug given by drip into a vein.

Brand names: ProvayBlue

Manufacturer: Provepharm SAS

Indication: Acquired methemoglobinemia in children and adults.

Source: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=4f6848e5-35ed-4046-b13c-3032b5ba3232

### Lawful compounding

Detail: Pharmacies may compound with a raw substance that meets a USP standard or is part of an FDA-approved drug. A compounded product is not FDA-approved.

Source: https://www.fda.gov/drugs/human-drug-compounding/bulk-drug-substances-used-compounding-under-section-503a-fdc-act

## Unofficial channels

Source: https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/north-isle-wellness-center-607947-06192020

### Clinic or med spa

What it is: Wellness centers that sold methylene blue capsules and other methylene blue products on their websites with claims about COVID-19.

Legal position: FDA called these products unapproved new drugs and misbranded drugs. Shipping them across state lines is prohibited under federal law. (source: https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/north-isle-wellness-center-607947-06192020)

Documented risks:

- The products were sold to prevent or treat COVID-19. FDA and the Federal Trade Commission said no study was known to show that they could. (source: https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/north-isle-wellness-center-607947-06192020)
- FDA advised consumers not to buy or use products it had not approved that were sold with COVID-19 claims. (source: https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/center-wellness-and-integrative-medicine-608693-06302020)

Enforcement:

- 2020-06-19: FDA and Federal Trade Commission warning letter to a wellness center that sold methylene blue products online with COVID-19 claims. (source: https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/north-isle-wellness-center-607947-06192020)
- 2020-06-30: FDA and Federal Trade Commission warning letter to a wellness center that sold methylene blue capsules online with COVID-19 claims. (source: https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/center-wellness-and-integrative-medicine-608693-06302020)

Source: https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/north-isle-wellness-center-607947-06192020

## Recruiting trials

Snapshot date: 2026-10-26.

A listing is not a recommendation. Trials have strict eligibility rules. Talk to your doctor and read the official record.

None in this snapshot.

Source: https://clinicaltrials.gov/api/v2/studies?query.intr=USP+methylene+blue&filter.overallStatus=RECRUITING%2CNOT_YET_RECRUITING&pageSize=50&sort=StartDate%3Adesc&countTotal=true&fields=NCTId%2CBriefTitle%2COverallStatus%2CPhase%2CLeadSponsorName%2CStartDate%2CLocationCountry%2CLocationState

## Sources

Source: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=4f6848e5-35ed-4046-b13c-3032b5ba3232

### 1. Drugs@FDA: ProvayBlue (methylene blue) injection, application 204630

Type: regulatory

Tier: primary

Source: https://www.accessdata.fda.gov/scripts/cder/daf/index.cfm?event=overview.process&ApplNo=204630

### 2. DailyMed: ProvayBlue (methylene blue) injection label, revised February 2024

Type: label

Tier: primary

Source: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=4f6848e5-35ed-4046-b13c-3032b5ba3232

### 3. FDA: bulk drug substances used in compounding under section 503A

Type: regulatory

Tier: primary

Source: https://www.fda.gov/drugs/human-drug-compounding/bulk-drug-substances-used-compounding-under-section-503a-fdc-act

### 4. FDA: 503A bulk drug substances category list, updated May 2026

Type: regulatory

Tier: primary

Source: https://www.fda.gov/media/94155/download

### 5. FDA guidance: compounded drugs that are essentially copies, January 2018

Type: regulatory

Tier: primary

Source: https://www.fda.gov/media/98973/download

### 6. FDA warning letter: methylene blue capsules sold with COVID-19 claims, 30 June 2020

Type: regulatory

Tier: primary

Source: https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/center-wellness-and-integrative-medicine-608693-06302020

### 7. FDA warning letter: methylene blue products sold with COVID-19 claims, 19 June 2020

Type: regulatory

Tier: primary

Source: https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/north-isle-wellness-center-607947-06192020

### 8. Randomized trial: methylene blue and brain scans of memory in healthy adults, 2016

Type: rct

Tier: peer-reviewed

Source: https://pubmed.ncbi.nlm.nih.gov/27351678/

### 9. Randomized crossover trial: methylene blue in bipolar disorder, 2017

Type: rct

Tier: peer-reviewed

Source: https://pubmed.ncbi.nlm.nih.gov/27284082/

### 10. Enzyme study: methylene blue, MAO A and serotonin toxicity, 2007

Type: in-vitro

Tier: peer-reviewed

Source: https://pubmed.ncbi.nlm.nih.gov/17721552/

### 11. Systematic review and meta-analysis: methylene blue in septic shock, 2024

Type: systematic-review

Tier: peer-reviewed

Source: https://pubmed.ncbi.nlm.nih.gov/38904978/

### 12. Mouse study: methylene blue and spatial memory after brain injury, 2025

Type: animal

Tier: peer-reviewed

Source: https://pubmed.ncbi.nlm.nih.gov/40879922/

### 13. Hematology report: methylene blue and G6PD deficiency, 2024

Type: reference

Tier: peer-reviewed

Source: https://pubmed.ncbi.nlm.nih.gov/38606972/

### 14. Review: methylene blue as an antidote for methemoglobinemia, 2021

Type: reference

Tier: peer-reviewed

Source: https://pubmed.ncbi.nlm.nih.gov/34463662/

### 15. ClinicalTrials.gov NCT02380573: methylene blue in healthy aging, mild cognitive impairment and Alzheimer's disease

Type: reference

Tier: primary

Source: https://clinicaltrials.gov/study/NCT02380573

### 16. ClinicalTrials.gov NCT01836094: USP methylene blue, memory and brain scans

Type: reference

Tier: primary

Source: https://clinicaltrials.gov/study/NCT01836094

### 17. NPR: methylene blue wellness claims and the research, December 2025

Type: reference

Tier: established-news

Source: https://www.npr.org/2025/12/15/nx-s1-5634680/methylene-blue-supplement-safety

Last verified: 2026-10-26.

Sources:

- https://clinicaltrials.gov/api/v2/studies?query.intr=USP+methylene+blue&filter.overallStatus=RECRUITING%2CNOT_YET_RECRUITING&pageSize=50&sort=StartDate%3Adesc&countTotal=true&fields=NCTId%2CBriefTitle%2COverallStatus%2CPhase%2CLeadSponsorName%2CStartDate%2CLocationCountry%2CLocationState
- https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=4f6848e5-35ed-4046-b13c-3032b5ba3232
- https://peptideindex.ai/methodology#evidence-grade
- https://peptideindex.ai/methodology#short-answer
- https://pubmed.ncbi.nlm.nih.gov/17721552/
- https://pubmed.ncbi.nlm.nih.gov/27351678/
- https://www.accessdata.fda.gov/scripts/cder/daf/index.cfm?event=overview.process&ApplNo=204630
- https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/north-isle-wellness-center-607947-06192020
- https://www.npr.org/2025/12/15/nx-s1-5634680/methylene-blue-supplement-safety

[^1]: Drugs@FDA: ProvayBlue (methylene blue) injection, application 204630 https://www.accessdata.fda.gov/scripts/cder/daf/index.cfm?event=overview.process&ApplNo=204630
[^2]: DailyMed: ProvayBlue (methylene blue) injection label, revised February 2024 https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=4f6848e5-35ed-4046-b13c-3032b5ba3232
[^3]: FDA: bulk drug substances used in compounding under section 503A https://www.fda.gov/drugs/human-drug-compounding/bulk-drug-substances-used-compounding-under-section-503a-fdc-act
[^4]: FDA: 503A bulk drug substances category list, updated May 2026 https://www.fda.gov/media/94155/download
[^5]: FDA guidance: compounded drugs that are essentially copies, January 2018 https://www.fda.gov/media/98973/download
[^6]: FDA warning letter: methylene blue capsules sold with COVID-19 claims, 30 June 2020 https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/center-wellness-and-integrative-medicine-608693-06302020
[^7]: FDA warning letter: methylene blue products sold with COVID-19 claims, 19 June 2020 https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/north-isle-wellness-center-607947-06192020
[^8]: Randomized trial: methylene blue and brain scans of memory in healthy adults, 2016 https://pubmed.ncbi.nlm.nih.gov/27351678/
[^9]: Randomized crossover trial: methylene blue in bipolar disorder, 2017 https://pubmed.ncbi.nlm.nih.gov/27284082/
[^10]: Enzyme study: methylene blue, MAO A and serotonin toxicity, 2007 https://pubmed.ncbi.nlm.nih.gov/17721552/
[^11]: Systematic review and meta-analysis: methylene blue in septic shock, 2024 https://pubmed.ncbi.nlm.nih.gov/38904978/
[^12]: Mouse study: methylene blue and spatial memory after brain injury, 2025 https://pubmed.ncbi.nlm.nih.gov/40879922/
[^13]: Hematology report: methylene blue and G6PD deficiency, 2024 https://pubmed.ncbi.nlm.nih.gov/38606972/
[^14]: Review: methylene blue as an antidote for methemoglobinemia, 2021 https://pubmed.ncbi.nlm.nih.gov/34463662/
[^15]: ClinicalTrials.gov NCT02380573: methylene blue in healthy aging, mild cognitive impairment and Alzheimer's disease https://clinicaltrials.gov/study/NCT02380573
[^16]: ClinicalTrials.gov NCT01836094: USP methylene blue, memory and brain scans https://clinicaltrials.gov/study/NCT01836094
[^17]: NPR: methylene blue wellness claims and the research, December 2025 https://www.npr.org/2025/12/15/nx-s1-5634680/methylene-blue-supplement-safety