Methylene Blue Ph. Eur.


CAS no. 7220-79-3, 122965-43-9

Methylene Blue, also called Methylthioninium Chloride has its applications in various industries, mainly as a dye and in medicine. 

In medicine it is used to treat methemoglobinemia, cyanide poisoning, ifosfamide toxicity, septic shock, anaphylaxis and more. In veterinary it is used in aquacultureas a treatment for fungal and parasitic infections.

Other uses of Methylene Blue include: water testing, as a dye or stain, sulfide analysis, biological staining, redox indicator or peroxide generator.

BHM Chemicals is a supplier of high quality Methylene Blue available in various grades: PH. Eur., USP and more depending on the end application.

Minimum order quantity: 10kg

Methylene blue, a remarkable chemical compound with a vivid blue color, has a rich history and versatile applications in various fields, from medicine to industrial chemistry. 


Methylene blue, also known as methylthioninium chloride, was first synthesized in the mid-19th century. It was developed by the German chemist Heinrich Caro in 1876. The vibrant blue dye quickly found use in the textile industry as a fabric dye.

However, it was not long before methylene blue's applications extended beyond textiles. In 1891, the German physician Paul Ehrlich discovered its potential as a biological stain. This discovery revolutionized the field of microbiology and histology by allowing scientists to visualize and study cellular structures and microorganisms more effectively.

Over the years, methylene blue has continued to evolve as a versatile compound with applications ranging from medical diagnostics to wastewater treatment and beyond.


  1. Chemical Structure. Methylene blue is a heterocyclic aromatic compound with a distinctive blue color. Its chemical formula is C16H18ClN3S, and its structure consists of three benzene rings linked by nitrogen and sulfur atoms.
  2. Water-Solubility and Color. One of methylene blue's notable properties is its high water solubility, which imparts its vibrant blue color. This characteristic makes it a valuable dye in various applications.
  3. Redox Chemistry. Methylene blue is a redox-active compound, meaning it can readily accept and donate electrons. This property makes it useful in redox titrations in analytical chemistry and as a redox indicator in chemical reactions.
  4. Biological Affinity. Methylene blue has a remarkable affinity for biological structures. It can bind to cellular components, such as DNA and mitochondria, making it useful for staining tissues in histology and as a tool for studying cellular respiration and other metabolic processes.


  1. Diagnostics. Methylene blue is employed in various medical diagnostic procedures. In urology, it is used to identify ureteral reflux during cystoscopy. Additionally, it can be used as a contrast dye for certain radiological studies.
  2. Surgery. In surgery, methylene blue can be injected into blood vessels to help visualize their anatomy, aiding in procedures such as angiography.
  3. Antidote: Methylene blue is an antidote for methemoglobinemia, a condition in which the oxygen-carrying capacity of hemoglobin is impaired. It helps convert methemoglobin back into functional hemoglobin, restoring oxygen transport in the blood.Microbiology
  4. Staining. Methylene blue is a vital stain used in microbiology to enhance the contrast of microorganisms under the microscope. It is particularly useful for staining gram-negative bacteria.Psychiatry
  5. Treatment of Mood Disorders. Emerging research suggests that methylene blue may have potential therapeutic benefits in treating mood disorders, such as depression and bipolar disorder. It is thought to work by enhancing mitochondrial function and improving energy production in neurons.Industrial and Environmental Applications
  6. Dyeing. Methylene blue is still used as a fabric dye in the textile industry, particularly for coloring cotton and wool.
  7. Wastewater Treatment. Methylene blue is employed in wastewater treatment processes to remove pollutants, including heavy metals. Its adsorption properties make it effective in binding to contaminants, facilitating their removal.Research
  8. Redox Indicator. In chemical and biological research, methylene blue is used as a redox indicator to monitor redox reactions and electron transport processes.


  1. Treatment of Methemoglobinemia. One of the most critical benefits of methylene blue is its role in treating methemoglobinemia, a condition that can be life-threatening if left untreated. Methylene blue rapidly converts methemoglobin, which cannot transport oxygen, back into functional hemoglobin, restoring oxygen-carrying capacity in the blood.
  2. Diagnostic Accuracy. Methylene blue enhances the accuracy of various medical and diagnostic procedures. Its use as a contrast dye helps visualize blood vessels and urinary reflux during medical imaging and cystoscopy, respectively. Additionally, it aids in identifying microbial specimens under the microscope.
  3. Research Applications. In research, methylene blue serves as a versatile tool. It is utilized as a redox indicator to monitor electron transfer processes and as a stain to visualize cellular structures and microorganisms. Its versatility makes it an indispensable component of many laboratory studies.
  4. Potential Role in Mood Disorders. Emerging research suggests that methylene blue may have a role in the treatment of mood disorders. By enhancing mitochondrial function and energy production in neurons, it may offer a novel approach to managing conditions such as depression and bipolar disorder. However, further clinical studies are needed to establish its efficacy definitively.

Safety Considerations

While methylene blue is generally safe when used appropriately, there are some safety considerations to keep in mind:

  1. Allergic Reactions. Rarely, individuals may experience allergic reactions to methylene blue, including skin rash, itching, and difficulty breathing. Anyone experiencing these symptoms should seek immediate medical attention.
  2. Dosing and Administration. Methylene blue should be administered under the guidance of a healthcare professional, particularly when used to treat medical conditions. The dose and route of administration must be carefully determined to avoid adverse effects.
  3. Methylene Blue in Pregnancy. The use of methylene blue during pregnancy or breastfeeding should be carefully considered, and its benefits should outweigh potential risks. Consultation with a healthcare provider is essential.
  4. Interaction with Medications. Methylene blue can interact with various medications, particularly those that affect serotonin levels, such as selective serotonin reuptake inhibitors (SSRIs). Combining methylene blue with these medications can lead to serotonin syndrome, a potentially life-threatening condition.

Methylene blue, with its vibrant blue color and unique properties, has made significant contributions to various fields, from medicine and microbiology to industrial applications. Its historical significance in staining tissues and its critical role in treating methemoglobinemia highlight its versatility and importance in healthcare.

As research continues to uncover new potential benefits, such as its use in mood disorders, methylene blue's significance in medicine and research may expand even further. However, it is essential to use this compound with care, under the guidance of healthcare professionals, and to remain vigilant about potential interactions and allergic reactions.

Methylene blue serves as an excellent example of how a chemical compound initially developed as a textile dye can evolve into a valuable tool for understanding and improving human health and the environment.

Please note that the information provided in this article is for informational purposes only and should not be considered a substitute for professional medical advice. Always consult with healthcare professionals or chemists for guidance on the appropriate use and handling of methylene blue in specific applications.


  1. Lüllmann, H., et al. (2018). Methylene blue in the early treatment of severe sepsis and septic shock. Pharmacological Research.
  2. Reisch, R., et al. (2017). Methylene Blue and Alzheimer's Disease. Biochemistry.
  3. van Beek, T. A., & Mead, G. J. (1989). Studies on Podophyllum spp.: the lignan composition of Podophyllum hexandrum. Phytochemistry.
  4. Saengkhae, C., et al. (2019). Mechanistic Insights into the Reaction of Methylene Blue with Reactive Oxygen Species in Solution. The Journal of Physical Chemistry A.
  5. DeVito, S. R., & Griffiths, R. P. (1993). Inhibition of Microbial Growth by Methylene Blue and Visible Light. Microbial Ecology.





Impurity A (Azure B)

Unspecified impurities

Sum of impurities (other than A)













Loss on drying

Sulfated ash

Assay (Content)



Dark blue or dark green, hygroscopic, crystalline powder with a metallic sheen. Slightly soluble in water and in ethanol (96%).

Conforms to Ph. Eur. tests

Maximum 5.0%

Maximum 0.1% (each)

Maximum 0.5%

Maximum 100ppm

Maximum 1ppm

Maximum 100ppm

Maximum 300ppm

Maximum 200ppm

Maximum 10ppm

Maximum 10ppm

Maximum 1ppm

Maximum 10ppm

Maximum 10ppm

Maximum 10ppm

Maximum 100ppm

8.0% to 24.0%

Maximum 0.25%

93.0% to 102.0% (dried substance)

Non-hazardous chemical

Keep container tightly closed in a cool and dry place and protected from light. Protect from contamination by foreign substances.