Methylene Blue
- Emma Jackson
- Jul 17
- 3 min read
Methylene Blue: A Clear‑Cut Guide to One of Medicine’s Oldest Modern Molecules
Methylene blue has been colouring lab slides since the 19th century, yet it is still turning heads in critical care, neurology and even the biohacking scene. This article breaks down what methylene blue is, how doctors use it, what the latest research says and why safety matters just as much as potential benefit.
(Medical disclaimer: Information here is for education only. Always consult a qualified clinician before using any medication or supplement.)
Key facts at a glance
Topic | Detail |
Chemical name | Methylthioninium chloride |
Class | Oxidation–reduction agent, diagnostic dye DrugBank |
Primary FDA‑approved use | Treatment of acquired methemoglobinemia (brand: ProvayBlue) Drugs.com |
Other established roles | Surgical dye, malaria therapy (historic), cyanide poisoning adjunct, vasoplegic shock rescue Drugs.com |
Investigational areas |
What exactly is methylene blue?
Methylene blue is a water‑soluble, deep‑blue compound first synthesised as a textile dye in 1876. In medicine it acts as an electron cycler: at low concentrations it accepts electrons from NADPH and donates them to oxidised haemoglobin, reversing methemoglobinemia. At higher doses it can do the opposite and worsen the condition, which is why precise dosing is critical. Life in the Fast Lane • LITFL
How methylene blue works
Redox cycling – Converts ferric (Fe³⁺) haemoglobin back to the oxygen‑carrying ferrous (Fe²⁺) state.
Nitric‑oxide pathway modulation – Inhibits soluble guanylyl cyclase, tightening blood vessels and raising blood pressure during vasoplegic shock. Life in the Fast Lane • LITFL
Mitochondrial support – Serves as an alternative electron carrier in the respiratory chain; theorised to improve cellular energy and reduce oxidative stress. Dr. Berg
Clinically proven uses
1. Methemoglobinemia
Best evidence, FDA‑labelledA single IV dose of 1–2 mg/kg usually restores normal oxygen transport within minutes. Contra‑indicated in G‑6‑PD deficiency due to risk of haemolysis. Drugs.com
2. Intra‑operative dye
Surgeons inject tiny volumes to map sentinel lymph nodes and check for leaks in bowel or bladder repairs. The vivid colour is easy to see and clears quickly. Drugs.com
3. Rescue therapy for vasoplegic shock
Cardiac theatres keep methylene blue on standby when extreme vasodilation fails to respond to catecholamines. Small studies suggest faster blood‑pressure recovery and shorter ICU stays. Evidence quality remains low. Wikipedia
Emerging and off‑label areas
Potential benefit | Current evidence | Key take‑away |
Alzheimer’s & other tauopathies | Phase II/III trials of low‑dose hydromethylthionine show slowed brain atrophy but mixed cognitive results. Larger studies in progress. Drugs.com | Promising but unproven. |
Anti‑ageing & biohacking | Influencers tout sub‑lingual drops for “cellular energy”. Data limited to small animal and in‑vitro models. Press coverage surged after RFK Jr. video. HealthNew York Post | No human RCTs confirming benefit. |
Photodynamic cancer therapy | Acts as a photosensitiser that produces reactive oxygen species under specific light wavelengths, damaging tumour cells. Mostly pre‑clinical. Benefits of Things | Experimental. |
COVID‑19 adjunct | Early lab studies found viral inhibition; clinical efficacy not established. Benefits of Things | Insufficient evidence. |
Typical dosing ranges
Indication | Route | Common dose |
Methemoglobinemia | IV | 1–2 mg/kg over 5 min (may repeat once if needed) |
Vasoplegic shock (off‑label) | IV | 1.5–2 mg/kg infusion over 30–60 min |
Cognitive research protocols* | Oral | 0.5–4 mg/kg daily (experimental) |
*Do not self‑dose. Oral use outside trials lacks regulatory approval.
Safety and side effects
Blue or green urine and stools (benign and temporary)
Dose‑related serotonin toxicity when combined with SSRIs or MAOIs
Hemolysis risk in G‑6‑PD deficiency
Skin discolouration, dizziness, nausea Drugs.com
Report severe reactions to a healthcare professional immediately.
Frequently asked questions
Is pharmaceutical‑grade methylene blue available over the counter? Only laboratory or aquarium products are OTC in many regions and may contain heavy‑metal contaminants. Medical‑grade solutions require a prescription in most countries.
Can I take methylene blue to boost memory? No human trial has yet confirmed cognitive benefit at safe doses. Stick to evidence‑based therapies until more data emerge. Drugs.com
Does it really fight ageing? Early cell studies suggest antioxidant effects, but there is no clinical proof that methylene blue slows ageing in humans. Dr. Berg
Bottom line
Methylene blue remains a vital antidote for methemoglobinemia and a handy surgical dye. New roles in shock management and neurodegenerative disease are exciting, but claims on social media outpace the science. If you are considering methylene blue for anything beyond its approved indications, seek advice from a clinician who understands both its potential and its pitfalls.
References
Drugs.com. “Methylene Blue – Uses, Dosage, Side Effects, Warnings.” Updated May 5 2025. Drugs.com
LITFL Critical Care Compendium. “Methylene Blue.” Dec 18 2024. Life in the Fast Lane • LITFL
DrugBank Online. Entry DB09241: Methylene Blue. DrugBank
Wikipedia. “Methylene blue.” Section on vasoplegic shock, updated 2024. Wikipedia
Health.com. “The Internet Thinks RFK Jr. Uses Methylene Blue.” Mar 2025. Health
New York Post. “Methylene blue: the anti‑aging liquid RFK Jr. seems to drink.” Feb 7 2025. New York Post
Benefits‑of‑Things.com. “Methylene Blue: Benefits, Side Effects, Uses.” Apr 2025. Benefits of Things
Dr Berg Blog. “Health Benefits of Methylene Blue.” Apr 8 2025. Dr. Berg
Sources