Methylene Blue History

 

Methylene blue (MB) is one of the oldest organic dyes, with a history dating back to 1876 when it was first synthesized by the German chemist Heinrich Caro. Originally developed as a textile dye, its vibrant blue color quickly made it popular in the textile industry. However, this was merely the beginning of its journey from a dye to a versatile chemical agent.

By 1890, researchers began to explore the medical potential of methylene blue. Microbiologist Robert Koch established its use for medical staining, while the German physician and Nobel laureate Paul Ehrlich investigated its antimicrobial properties and discovered its efficacy against specific bacterial and protozoal infections.

Furthermore, Dr. Paul Ehrlich noted that this dye could stain living neurons (which proved highly beneficial years later) and had the same effect on Plasmodium, the parasite causing malaria present in human blood. He deduced that the dye could selectively target malaria within the human body. A few years later, he successfully tested MB for treating malaria, marking the first instance of an infectious disease being cured by a synthetic compound. Despite this breakthrough, quinine was already the established antimalarial treatment at the time, leading to a decline in MB's use. This persisted until malaria began to show increased resistance to existing modern drugs. Several years ago, Professor Dr. Olaf Müller found that MB surpasses all known antimalarials in crucial aspects. In fact, it may be the most effective available agent for inhibiting the transmission of infection.

In the late 19th century, MB was also intensively researched as a treatment for schizophrenia. It was one of the first drugs used to treat patients with psychosis and was a cornerstone in the serendipitous development of phenothiazine antipsychotics in the mid-20th century.

In the 1980s, Dr. Claude Wischik, working in a Cambridge laboratory, was part of a team studying Alzheimer's disease. His initial task was to isolate neuronal aggregates before they could be examined in depth. His colleagues suggested using MB on the neuronal samples. To Wischik's surprise, MB not only stained the aggregates but also dissolved them. A key realization for him was that MB had been used previously—and still is—in psychiatric research, indicating its ability to cross the blood-brain barrier. Wischik discovered that the aggregates were composed of tau, a protein normally present in the brain that, in Alzheimer's patients, misfolds and aggregates into larger oligomers. His findings sparked a surge of research into MB. Today, this remarkable compound is being investigated as a treatment for neuropsychiatric conditions.

By 2025, there are over 28,200 entries for "methylene blue" in the biomedical database PubMed, not including studies published during periods not covered by PubMed.

Today, it is medically approved for the treatment of methemoglobinemia. Furthermore, it has found application in treating ifosfamide-induced encephalopathy, as an intervention for urinary tract infections in elderly patients, as an antidote for carbon monoxide and cyanide poisoning, and as a treatment for septic shock.

It is also still used as a diagnostic tool in surgical procedures, in histopathology laboratories as a cellular structure stain (for staining or highlighting sections of animal, bacterial, and blood tissues), and for inactivating bacteria.