What is methylene blue?
Methylene blue is a synthetic blue dye, also known as methylthioninium chloride. It is used in laboratory staining and, in specific pharmaceutical formulations, as a medicine.
Its medical use
In the United States, methylene blue injection is approved to treat acquired methemoglobinemia, a condition that reduces the blood’s ability to carry oxygen. It works by helping restore hemoglobin to its oxygen-carrying form.
What to know before use
Methylene blue can interact dangerously with certain antidepressants and opioids. It is contraindicated in people with G6PD deficiency. Medical use requires professional guidance; laboratory dyes are not medicines.