Comparison
Methylene Blue vs PT-141
Side-by-side of Methylene Blue and PT-141. 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.
PT-141
PT-141 peptide (bremelanotide, Vyleesi): MC4R agonist for libido and erectile dysfunction. 1.75 mg subcutaneous, 30 to 60 min onset, 2 to 4 h half-life.
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
PT-141
- •Cyclic 7-amino-acid synthetic peptide and melanocortin receptor agonist (MC4R-preferring)
- •FDA approved in 2019 as Vyleesi for hypoactive sexual desire disorder in pre-menopausal women
- •Acts centrally on hypothalamic sexual-desire circuits rather than peripherally on vasculature
- •On-demand dosing: subcutaneous 1.75 mg approximately 45 minutes before sexual activity
- •Common adverse effects: nausea (~40%), flushing, headache, injection-site reactions, hyperpigmentation
- •Off-label male ED use is documented but not FDA approved; mechanism is distinct from PDE5 inhibitors
Side-by-side
| Attribute | Methylene Blue | PT-141 |
|---|---|---|
| Category | pharmaceutical | peptide |
| Also known as | Methylthioninium chloride, Provayblue, tetramethylthionine chloride | Bremelanotide, Vyleesi |
| Half-life (hr) ↗ | 5.5 | 2.7 |
| Typical dose (mg) ↗ | 70 | 1.75 |
| Dosing frequency | 1 to 3 times daily for cognitive use; single IV dose for methemoglobinemia | as needed (max once per 24 hours, max 8 per month) |
| Routes | oral, intravenous | subcutaneous |
| Onset (hr) | 1 | 0.75 |
| Peak (hr) | 1.5 | 1.5 |
| Molecular weight | 319.85 | 1025.18 |
| Molecular formula | C16H18ClN3S | C50H68N14O10 |
| 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. | Synthetic agonist of melanocortin receptors with preference for MC4R, expressed in hypothalamic and limbic circuits regulating sexual motivation. Engages central pathways distinct from peripheral PDE5-mediated vasodilation. |
| Legal status | Prescription (injectable, FDA approved); supplement form (oral) widely available; not scheduled | Prescription only as Vyleesi; FDA-approved 2019 for HSDD in pre-menopausal women. Compounded versions sold off-label for male sexual function are research-use-only grey market. |
| WADA status | allowed | allowed |
| DEA / Rx | Not scheduled in the US | Rx only (not a controlled substance) for the FDA-approved Vyleesi formulation |
| Pregnancy | Contraindicated | Not recommended; contraindicated during pregnancy per Vyleesi label |
| CAS | 61-73-4 | 189691-06-3 |
| PubChem CID | 6099 | 9941379 |
| Wikidata | Q409021 | Q422059 |
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)
PT-141
Common side effects
- nausea (~40%)
- flushing
- headache
- injection-site reactions
- hyperpigmentation (focal, gums, face, breasts)
- transient blood pressure increase (~6 mmHg systolic)
Contraindications
- uncontrolled hypertension
- established cardiovascular disease
- pregnancy
- naltrexone co-administration (reduces opioid efficacy due to MC receptor crosstalk)
Interactions
- naltrexone (oral): bremelanotide reduces oral naltrexone exposure significantly; avoid co-administration(major)
- antihypertensives: transient BP rise after bremelanotide can offset BP control(moderate)
- PDE5 inhibitors (sildenafil, tadalafil): no documented adverse interaction; mechanisms are non-overlapping(minor)
Which Should You Take?
Methylene Blue comes out ahead for most readers on the criteria we weight: 3 catalogued goals, controlled substance, oral dosing, with a Tier-A outcome catalogued. PT-141 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 mitochondrial function, pick Methylene Blue.
- → If your priority is sexual function, pick PT-141.
- → If your priority is libido, pick PT-141.
Edge case: If you cannot self-administer injections, Methylene Blue is the only oral option in this pair.
Default choice: Methylene Blue. Wider use case, a Tier-A evidence outcome catalogued, and broader goal coverage. Reach for PT-141 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 PT-141?
Methylene Blue and PT-141 differ in category (pharmaceutical vs peptide), mechanism, and typical dosing. See the side-by-side table for full details.
Which has a longer half-life, Methylene Blue or PT-141?
Methylene Blue half-life is 5.5 hours; PT-141 half-life is 2.7 hours.
Can you stack Methylene Blue with PT-141?
Stack compatibility depends on mechanism overlap, legal status, and individual response. Check each compound page for specific interactions and contraindications before combining.
Go deeper