Comparison
Methylene Blue vs TUDCA
Side-by-side of Methylene Blue and TUDCA. Every row below is pulled from the compound schema and will update as our data grows. For deeper reads, follow through to each compound page.
Methylene Blue
Methylene blue as a nootropic: low-dose cognitive enhancement, mitochondrial electron cycling, brain oxygen uptake, SSRI interaction risk, typical 0.5 to 4 mg.
TUDCA
TUDCA is the taurine-conjugated form of ursodeoxycholic acid, a bile-acid molecule with replicated effects on liver function, ER stress, and bile flow.
Effects at a glance
Methylene Blue
- •FDA approved for methemoglobinemia and ifosfamide-induced encephalopathy
- •Mitochondrial electron-transport support at low doses (0.5 to 4 mg/kg) via cytochrome c shuttle
- •Potent MAO-A inhibitor; serotonin syndrome risk with SSRIs, SNRIs, MAOIs, fentanyl, tramadol, St John's wort
- •Causes harmless blue-green urine and sweat coloration; useful adherence marker
- •G6PD deficiency is an absolute contraindication; can trigger massive hemolysis
- •Cognitive-enhancement evidence is preliminary, mostly preclinical and small fMRI trials
TUDCA
- •Bile-acid molecule (taurine-conjugated UDCA) with chemical chaperone activity at the endoplasmic reticulum
- •Established pharmaceutical use for cholestasis and primary biliary cholangitis at 500-750 mg/day
- •Reduces ER stress and stabilizes misfolded proteins; the mechanistic basis for emerging ALS / retinal applications
- •Modest improvements in NAFLD markers and insulin sensitivity at 500-1,750 mg/day in small trials
- •Mitochondrial protection signal in animal models drives the longevity-supplement positioning
- •Generally well-tolerated; mild GI effects are the main dose-dependent issue
Side-by-side
| Attribute | Methylene Blue | TUDCA |
|---|---|---|
| Category | pharmaceutical | supplement |
| Also known as | Methylthioninium chloride, Provayblue, tetramethylthionine chloride | tauroursodeoxycholic acid, taurine-conjugated UDCA |
| Half-life (hr) ↗ | 5.5 | 4 |
| Typical dose (mg) ↗ | 70 | 500 |
| Dosing frequency | 1 to 3 times daily for cognitive use; single IV dose for methemoglobinemia | daily, divided into 2 doses with food |
| Routes | oral, intravenous | oral |
| Onset (hr) | 1 | 1 |
| Peak (hr) | 1.5 | 2 |
| Molecular weight | 319.85 | 499.7 |
| Molecular formula | C16H18ClN3S | C26H45NO6S |
| Mechanism | Mitochondrial electron carrier at low doses (cytochrome c shuttle to complex IV) and methemoglobin reductase substrate at higher doses; potent MAO-A inhibitor across the dose range. | Bile-acid signaling via FXR/TGR5 receptors; chemical chaperone reducing ER stress and unfolded protein response; mitochondrial protection through reduced outer-membrane permeabilization. |
| Legal status | Prescription (injectable, FDA approved); supplement form (oral) widely available; not scheduled | OTC dietary supplement (US); pharmaceutical in Italy and several Asian countries |
| WADA status | allowed | allowed |
| DEA / Rx | Not scheduled in the US | OTC supplement |
| Pregnancy | Contraindicated | Insufficient data for supplement use; UDCA used in cholestasis of pregnancy |
| CAS | 61-73-4 | 14605-22-2 |
| PubChem CID | 6099 | 9848818 |
| Wikidata | Q409021 | Q418751 |
Safety profile
Methylene Blue
Common side effects
- blue-green urine and sweat
- skin and oral mucosa staining
- GI upset
- headache
- dizziness
Contraindications
- G6PD deficiency
- pregnancy
- concurrent serotonergic medication
- severe renal impairment
- infants under 6 months
Interactions
- SSRIs and SNRIs: serotonin syndrome, potentially fatal(major)
- MAOIs: additive MAO inhibition, serotonin syndrome risk(major)
- fentanyl, tramadol, meperidine: serotonin syndrome risk(major)
- dextromethorphan: serotonin syndrome risk(major)
- St John's wort: serotonin syndrome risk(major)
- lithium: additive serotonergic risk(major)
TUDCA
Common side effects
- mild GI upset
- diarrhea (dose-dependent)
- constipation (rare)
- nausea
Contraindications
- complete biliary obstruction
- pregnancy / lactation (insufficient supplement-dose data)
- active GI disease without medical supervision
Interactions
- cyclosporine, oral contraceptives, fat-soluble vitamins: modest absorption changes via altered bile-acid pool(minor)
- phenylbutyrate: synergistic for ALS use (Relyvrio combination); consult clinician(moderate)
Which Should You Take?
TUDCA comes out ahead for most readers on the criteria we weight: 3 catalogued goals, OTC dietary supplement, oral dosing, with a Tier-A outcome catalogued. Methylene Blue is the right call when one of the conditionals below applies.
- → If your priority is focus or working memory, pick Methylene Blue.
- → If your priority is antimicrobial action, pick Methylene Blue.
- → If your priority is liver function, pick TUDCA.
- → If your priority is healthspan extension, pick TUDCA.
Edge case: If you want to avoid controlled substance, TUDCA is the more accessible choice.
Default choice: TUDCA. Lower friction to source, a Tier-A evidence outcome catalogued, and broader goal coverage. Reach for Methylene Blue only if your priority sits squarely in the goals it owns above.
This verdict is generated from each compound's schema (goals, legal status, evidence outcomes, dosing route). It updates automatically as our compound data evolves; the deeper read sits on each individual compound page.
Common questions
What is the difference between Methylene Blue and TUDCA?
Methylene Blue and TUDCA differ in category (pharmaceutical vs supplement), mechanism, and typical dosing. See the side-by-side table for full details.
Which has a longer half-life, Methylene Blue or TUDCA?
Methylene Blue half-life is 5.5 hours; TUDCA half-life is 4 hours.
Can you stack Methylene Blue with TUDCA?
Stack compatibility depends on mechanism overlap, legal status, and individual response. Check each compound page for specific interactions and contraindications before combining.
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