INTRODUCTION

Methylene blue (MB), a basic thiazine dye has been used clinically for about a century to treat numerous ailments. Primarily used in the treatment of methemoglobinemia, as an antidote in cyanide poisoning, as a biological stain, and as an oxidant-reduction indicator.

The intravenous form of MB is approved by the FDA for the treatment of pediatric and adult patients with acquired methemoglobinemia. MB is an investigational drug being developed by the University of Aberdeen and TauRx Therapeutics that has been shown in early clinical trials to be an inhibitor of Tau protein aggregation. The drug is also of potential interest for the treatment of patients with Alzheimer’s disease.

SynonymsMethylthioninium chloride
Basic blue 9 (C.I. 52015)
CAS no.122965-43-9 (hydrate)
7220-79-3 (trihydrate)
61-73-4 (anhydrous)
EINECS no.602-909-3 (hydrate)
615-731-6 (trihydrate)
200-515-2 (anhydrous)
Molecular formulaC16H18N3S.Cl.xH2O
Molecular weight337.90 (hydrate & trihydrate)
319.85 (anhydrous)
Structure

MEDICAL APPLICATIONS

MethemoglobinemiaMB is employed as a medication for the treatment of methemoglobinemia
Combined with lightMB combined with light has been used to treat resistant plaque psoriasis
Urinary tract infectionMB is a component of a urinary analgesic/anti-infective/anti-spasmodic known as “Prosed DS”, a combination of phenyl salicylate, benzoic acid, hyoscyamine sulfate, and methenamine (aka hexamethylenetetramine and not to be confused with ‘methanamine’)
Cyanide poisoningSince its reduction potential is similar to that of oxygen and can be reduced by components of the electron transport chain, large doses of methylene blue are sometimes used as an antidote to potassium cyanide poisoning
Dye or stainMB is used in endoscopic polypectomy as an adjunct to saline or epinephrine and is used for injection into the submucosa around the polyp to be removed
PlaceboMB has been used as a placebo; physicians would tell their patients to expect their urine to change color and view this as a sign that their condition had improved
Ifosfamide toxicityAnother use of methylene blue is to treat Ifosfamide neurotoxicity
ShockIt has also been used in septic shock and anaphylaxis

OTHER APPLICATIONS

Redox indicatorMB is widely used as a redox indicator in analytical chemistry
Peroxide generatorMB is also a photosensitizer used to create singlet oxygen when exposed to both oxygen and light
Biological stainingIn biology MB is used as a dye for number of different staining procedures, such as Wright’s stain and Jenner’s stain. Since it is a temporary staining technique, MB can also be used to examine RNA or DNA under the microscope or in a gel
AquacultureMB is used in aquaculture and by tropical fish hobbyists as a treatment for fungal infections

Modes of action of Methylene Blue in SARS-CoV-2 infection complications (as per the current ongoing studies. Concrete data to be available soon)

It inhibits SARS-CoV-2 spike ACE2 protein – protein interaction
To treat Cytokinin Storm which is one of the major reason for ADRs, Multiorgan Failure & Mortality
It relieves oxidative stress, ROS and free radicals
It increases systemic vascular resistance (SVR) in septic shock
It causes antifibrotic action in lungs

SPECIFICATIONS
MB offered by Exsyn complies USP & EP pharmacopeia. Please ask our sourcing team if you need detailed specifications.

WRITTEN CONFIRMATION (WC)
ExSyn offers MB with WC certification, so it can be sold to the EU as an API for human consumption.

STORAGE
Temporary storage temperature is below 30°C
Long term storage temperature is 5°C ± 3°C

ExSyn offers MB on commercial scale and welcomes enquiries. No matter the quantity you need, our exceptional quality and service will make ExSyn your supplier of choice! If you need any additional information or SDS, please get in touch with us.

More Products in focus
In focus: Diacetone Alcohol
Products in focus · 29/09/2026

Diacetone Alcohol (DAA) is an aliphatic hydroxy ketone produced through the base-catalysed aldol addition of two acetone molecules. It contains both ketone and tertiary hydroxyl functionalities, offering excellent solvency and chemical reactivity.

As a high-boiling oxygenated solvent and valuable chemical intermediate, DAA finds broad application in paints and coatings, printing inks, adhesives, industrial cleaning, cosmetics, and textiles. It is also used as an intermediate in the production of mesityl oxide and MIBK. (4-methylpentan-2-one).

READ MORE
In focus: Kojic Acid
Products in focus · 22/09/2026

Kojic acid is a natural fungal metabolite produced through natural fermentation of carbohydrates. It works primarily as a tyrosinase inhibitor, suppressing melanin production to help reduce dark spots and even out skin tone. It also delivers antioxidant benefits, neutralizing free radicals and protecting skin cells from oxidative stress. With its naturally weak acidic profile, kojic acid is a multifunctional ingredient suited for brightening and protective skincare formulations.

READ MORE
In focus: (S)-Oxetan-2-yl-methanamine
Products in focus · 15/09/2026

(S)-Oxetan-2-yl-methanamine is a chiral oxetane-containing primary amine. The compound features a strained four-membered oxetane ring and an aminomethyl substituent, making it a valuable building block in modern medicinal chemistry. Due to its unique physicochemical properties, including increased polarity and metabolic stability compared with conventional alkyl groups, it is widely employed as an advanced pharmaceutical intermediate in drug discovery and development programs.

READ MORE
In focus: Guanidine Carbonate
Products in focus · 08/09/2026

Guanidine carbonate is a white, crystalline, water-soluble compound with an alkaline and ionic nature. Composed of guanidinium cations and carbonate anions, it offers chemical stability, buffering capacity, and good formulation compatibility. In textile applications, it is used in formulations and fabric treatments for its thickening, softening, lubricating, anti-static, and flame-retardant properties, contributing to improved fabric finish and performance.

READ MORE
In focus: Tin(II) sulfide
Products in focus · 01/09/2026

Tin(II) sulfide (SnS) has emerged as a safe and sustainable semiconductor owing to its non-toxicity, low cost, and natural abundance. It has attracted significant interest for solar energy conversion in thin-film photovoltaic devices because of its suitable band gap, which is approximately 1.3 eV in the orthorhombic phase and 1.5-1.7 eV in the cubic phase. In addition to photovoltaic applications, SnS is used in solid-state lubricants, near-infrared detectors, Lithium-ion batteries, and various sensing devices.

READ MORE
In focus: Nikethamide BP (N,N-Diethylnicotamide)
Products in focus · 25/08/2026

Nikethamide is a synthetic organic compound derived from nicotinic acid (vitamin B₃). It consists of a pyridine ring linked to a diethyl amide functional group and belongs to the class of pyridine amide derivatives.

READ MORE
In focus: (2-Methoxy-1-methyl-2-oxoethyl)triphenylphosphoniumbromide
Products in focus · 18/08/2026

(2-Methoxy-1-methyl-2-oxoethyl)triphenylphosphonium bromide is a stabilized phosphonium salt widely used as an intermediate in organic synthesis. Due to presence of an ester group, the compound generates a stabilized ylide that is particularly useful for synthesizing α, β-unsaturated esters, valuable intermediates in pharmaceuticals, agrochemicals, fragrances, and fine chemicals.

READ MORE
In focus: p-tert-butylphenol (PTBP)
Products in focus · 11/08/2026

p-tert-Butylphenol (PTBP), is an aromatic organic compound consists of a phenol ring substituted with a tert-butyl group at the para (4-) position, giving it improved thermal stability and hydrophobic properties compared to phenol. PTBP features significant hydrogen bonding capabilities, which enhance its solubility in organic solvents. PTBP is used primarily as an intermediate in the manufacturing of polycarbonate plastics, phenolic resins, and epoxy resins.

READ MORE
In focus: Yttrium oxide
Products in focus · 04/08/2026

Yttrium oxide (Y2O3), also known as yttria, is an air-stable, odorless white powder. It is a highly stable, chemically inert ceramic with a very high melting point. It is insoluble in water but readily dissolves in most strong acids. Increasing the specific surface area and porosity of Y2O3 can further improve its relevant physical and chemical properties.

READ MORE