Methylene blue

Molecular formula:
C16H18N3SCl
Chemical compound:
methylene blue
Common name:

Methylene blue, or methylthioninium chloride, is a dye and a medication. In the first half of the 20th century, it was used as an antidote for cyanide poisoning. Now it is used to treat methemoglobinemia (one of the possible problems with oxygen transfer through the body via blood) and to color some structures such as cells, or to distinguish bone and cement when necessary. Methylene blue is also used to test water filters because its structure is similar to some of the major organic pollutants often found in water.

Similar reagents

Experiments with similar reagents

Hazard information

Hazard statements

  • Harmful if swallowed.
  • Causes skin irritation.
  • Causes serious eye irritation.
  • May cause respiratory irritation.

Precautionary statements

  • Avoid breathing dust/fume/ gas/mist/vapours/spray.
  • IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses if present and easy to do – continue rinsing.