Methylene blue is a chemical compound with a fascinating history and a wide range of applications in medicine, microbiology, veterinary medicine and even in the aquatic industry . Discovered in the 19th century as a textile dye, its impact on health and science has made it an essential drug in many treatments.
But what makes methylene blue so versatile? How is it actually used in different fields of science and health? Join us on this detailed tour of its uses in humans, laboratories, veterinary medicine, and more .
1. Methylene Blue in Medicine: Beyond a Dye
The use of methylene blue in medicine is based on its unique chemical properties. It functions as a reducing agent, antioxidant and cell modulator , allowing it to play a key role in various medical treatments.
1.1. Treatment of Methemoglobinemia: Restoring Oxygen Transport
Methemoglobinemia is a condition in which the hemoglobin in the blood loses its ability to carry oxygen, seriously affecting cellular respiration and body function. It can be inherited or caused by exposure to certain chemicals and medications.
✔ How does methylene blue act on blood?
When the body is unable to convert methemoglobin into normal hemoglobin, methylene blue acts as an electron donor , helping to restore the blood's ability to carry oxygen. This effect occurs within minutes when administered intravenously, making it an effective emergency treatment.
Cases in which it is used:
- Nitrate or nitrite poisoning in water.
- Overdose of drugs that induce methemoglobinemia.
- Treatment of some cases of cyanide poisoning.
1.2. Methylene Blue and its Impact on Neurodegenerative Diseases
The ability of methylene blue to enhance energy production in mitochondria has sparked great interest in the treatment of diseases such as Alzheimer's and Parkinson's .
✔ How does it help the brain?
Methylene blue improves mitochondrial function , increasing the production of ATP, which is the energy source of cells. It also reduces the accumulation of toxic proteins in neurons , which could slow down cognitive decline.
Recent studies have shown:
- Improves memory and cognitive function in people with early Alzheimer's.
- Neuroprotective effects in animal models of Parkinson's.
- Reduction of oxidative stress , protecting brain cells from premature aging.
Further clinical studies are still required, but methylene blue could become an innovative alternative in neurology.
1.3. Cyanide poisoning
Cyanide is a highly toxic substance that blocks the use of oxygen in cells. It can be fatal if not treated quickly. It can be inhaled in fires, industrial exposures, or even in bioterrorist attacks.
Although methylene blue was once used to treat cyanide poisoning, it is no longer recommended as a primary antidote. However, its effect on the body's chemical balance has been studied in this context.
Research Reference: Methylene Blue as an Antidote to Cyanide and Carbon Monoxide Poisoning
1.4. Use as placebo
Sometimes doctors use methylene blue as a placebo – that is, as a treatment that has no real effect on the disease but can influence patients’ perceptions. A common strategy is to tell patients to expect a change in the color of their urine as a sign of improvement, which reinforces the feeling that the treatment is working.
Research Reference: The Ethics of Deception in Medicine
1.5. Neurotoxicity of ifosfamide
Ifosfamide is a drug used in chemotherapy that, in some cases, can cause toxic effects on the brain, causing confusion, hallucinations or even seizures.
Methylene blue helps counteract this toxicity by acting on certain chemical reactions in the body's metabolism. Its dosage varies depending on use, whether as a preventative measure or as a treatment when symptoms have already appeared.
Research Reference: Methylene Blue for the Treatment of Ifosfamide-Induced Encephalopathy
1.6. Septic shock: when the body goes into crisis due to a serious infection
Septic shock is a medical emergency that occurs when a severe infection causes a dangerous drop in blood pressure, which can lead to multiple organ failure.
Methylene blue has been shown to be useful in these cases because it helps improve blood pressure when other treatments do not work. Although it has been used more in adults, there is also evidence that it can be effective in children.
1.7. Other medical uses
🔹 Vasoplegia after cardiac surgery: Vasoplegia is a common complication in patients undergoing cardiopulmonary surgery. Methylene blue can help stabilize blood pressure in these cases.
Research Reference: Methylene Blue: The Magic Solution for Vasoplegia
🔹 Alzheimer's: Research suggests that methylene blue may improve mitochondrial function and reduce the effects of Alzheimer's.
🔹 Malaria: The initial medicinal application of methylene blue was as a therapy against malaria. Its use as an antimalarial treatment has been studied for over a century. It has been shown to have a strong action against the parasite that causes malaria.
Research Reference – Potent gametocytocidal effect of methylene blue-based combination therapy against Falciparum malaria: a randomized controlled trial , Methylene blue for malaria in Africa: results of a dose-finding study in combination with chloroquine
🔹 Bipolar disorder: It has been investigated as an adjunctive treatment to reduce cognitive and emotional symptoms in people with bipolar disorder.
🔹 Cancer: In oncology, methylene blue is used in photodynamic therapy , a technique that helps kill cancer cells by activating the compound with special light. It is also used in the detection of oral cancer.
Research Reference: Methylene blue photodynamic therapy induces selective and massive cell death in human breast cancer cells
🔹 Photodynamic therapy (PDT): In addition to cancer, this technique is being investigated to treat infectious diseases such as leishmaniasis.
Research Reference: Methylene blue photodynamic therapy for treating cutaneous leishmaniasis,Methylene blue-mediated photodynamic therapy enhances apoptosis in lung cancer cells
🔹 Infectious diseases: Its ability to inactivate viruses and bacteria has been studied.
Research Reference: Non-photodynamic functions of methylene blue: visualizing distinct antimycobacterial and anticandidiasis modes of action
🔹 Anti-aging and skin health: Research indicates that methylene blue can improve cell regeneration, reduce wrinkles and increase the longevity of skin cells thanks to its antioxidant properties.
1.8. Methylene Blue Oral and Topical Use
Depending on the pathology, methylene blue is administered by different routes:
✔ Oral use: It has been tested in the treatment of urinary tract infections, malaria and metabolic disorders . Its effect on the balance of the intestinal microbiota and its antimicrobial potential are also being investigated.
✔ Topical use: It has been used to treat skin infections and promote cell regeneration in chronic wounds and diabetic ulcers. Its bactericidal action makes it an ally in dermatology.
2. Methylene Blue in the Laboratory: Essential Tool in Science
Methylene blue is a fundamental pillar in microbiology, biology and pathology . Its properties as a dye make it an indispensable tool in the observation of microorganisms and cells under the microscope.
2.1. Methylene Blue Staining in Microbiology
In microbiology laboratories, methylene blue is used to stain bacteria, cells and tissues , facilitating their identification in clinical and scientific studies.
✔ Common applications:
- Staining of Gram-negative bacteria in microbiological studies.
- Visualization of blood cells and cellular structures in hematological studies.
- Tissue differentiation in pathological analysis , useful in biopsies and disease diagnosis.
This use is vital for clinical analysis, medical diagnostics and cell biology studies .
2.2. Methylene Blue in Biomedical Research
In addition to its role as a dye, methylene blue is used in scientific research to:
- To evaluate mitochondrial activity in studies on cellular metabolism.
- Analyze responses to oxidative stress in cells exposed to toxins.
- Develop therapies for metabolic and neurodegenerative diseases .
Its ability to influence cellular metabolism has made it an object of study in many universities and research centers.
2.3. Oxygen indicator (Redox indicator)
Methylene blue changes color depending on the amount of oxygen in its environment:
✅ With oxygen: the solution turns blue.
❌ Without oxygen: the solution becomes colorless.
This change is used in experiments to detect the presence or absence of oxygen in a liquid.
2.4 Generation of peroxides
Methylene blue is a photosensitizer, meaning that when it comes into contact with light and oxygen, it can generate active oxygen. This process is used to produce organic peroxides, which are substances used in various chemical reactions.
2.5. Sulfide analysis
This method detects the presence of sulfide (H₂S) and metal sulfides in a sample. Methylene blue reacts with these compounds and produces a blue color, the intensity of which indicates the amount of sulfide present. This technique is widely used in chemical analysis.
2.6. Biological staining
This dye is ideal for visualizing cells under a microscope. Because it has a positive charge, it binds to negatively charged structures within cells, such as DNA and RNA.
Because of this property, methylene blue is used to study microorganisms such as yeast and to identify living and dead cells in biological samples.
3. Methylene Blue Veterinary Use: Applications in Animals
Methylene blue has also been shown to be useful in animal health. It is used in mammals, birds and fish for a variety of applications.
✔ Uses in mammals and birds:
- Treatment of poisoning in dogs and cats.
- Improving the immune system in poultry.
- Research into infectious diseases in livestock.
✔ Methylene blue in aquariums and fish:
- Treatment of fungal infections in fish eggs.
- Prevention of bacterial and parasitic diseases in aquariums.
- Protection of tropical fish against environmental infections.
This use is key to the aquaculture and aquarium industry , where a pathogen-free environment is required to maintain fish health.
4. Other Uses of Methylene Blue
In addition to its medical and scientific applications, methylene blue has been used in other sectors:
✔ Textile and ceramic industry: It was one of the first synthetic dyes used to dye fabrics and in the manufacture of ceramics.
✔ Use in dentistry: It has been used in the detection of oral lesions and diagnosis of infections in gums and teeth.
✔ Research in energy storage: Recent studies explore their use in flow batteries to store electricity more efficiently and sustainably.
✔ Water Quality Testing: Methylene blue is used to measure the amount of dissolved oxygen in water. If the water has enough oxygen, the color stays blue. But if there are chemicals that consume oxygen, the color fades. This method is useful for determining water quality and in tests such as biochemical oxygen demand (BOD), which assesses pollution in bodies of water.
✔ Mineral evaluation in construction: In the construction industry, methylene blue is used to analyze the quality of fine aggregates (materials such as sand used in the concrete mix). Clay minerals in these aggregates can affect the strength and durability of concrete, and methylene blue allows the amount of clay present in the mix to be measured.
✔ Disinfectant against bacteria and parasites : Methylene blue also has antibacterial and antiparasitic properties, making it an effective disinfectant. Its effect is believed to be due to the interaction with the cellular metabolism of bacteria and other microorganisms. For this reason, it has been used in some industries to prevent infections in different environments.
Conclusion
Methylene blue is much more than just a dye. Its ability to restore cellular function, fight infections and facilitate scientific research makes it a valuable tool in a variety of fields. From its use in medicine to its application in microbiology and veterinary medicine, its versatility continues to be the subject of study in modern science.
Although its therapeutic potential is still under evaluation, its impact on health and biology keeps it as a compound of interest for research and clinical practice.
