Tropical fish fanciers will be familiar with methylene blue as an anti-fungal and anti-bacterial chemical used to keep fish healthy. Today the Daily Mail report on a trial carried out in China by orthopedic surgeons and reviewed by Professor Bogduk for the medical journal Pain. The Chinese surgeons suggest that injecting Methylene Blue into lumbar discs will cure low back pain in one fifth of cases.
Methylene blue binds to small molecules such as nitric oxide which is known to cause inflammation, we know from previous research that reducing nitric oxide relieves pain in osteoarthritis so the approach has great potential.
An alternative theory that I reported on last month (read here) is that injured discs can become infected by bacteria, presumably methylene blue would act as an anti-bacterial in this case so the mechanism would be different but the beneficial effect would be the same.