The Effect of Methylene Blue Infiltrating Injection on Anal Pain After Milligan-Morgan Surgery: a Randomized Controlled Clinical Study

A variety of analgesic strategies are available following mixed hemorrhoids surgery, including pharmacological interventions (7), acupuncture, moxibustion, and electroacupuncture . Medications such as opioid analgesics and non-steroidal anti-inflammatory drugs (NSAIDs) are commonly used but can be associated with side effects including nausea, vomiting, and gastrointestinal bleeding, with long-term use potentially leading to addiction (8). Complementary therapies require skilled administration and regular treatment sessions. Methylene blue (MB), a cationic thiazine dye extensively utilized as a biological stain and chemical indicator, has been increasingly recognized for its potential analgesic properties (9). In the present study, methylene blue infiltrating injection (MBI) was administered to treat anal pain resulting from Milligan-Morgan surgery, with the aim of assessing its analgesic efficacy and safety profile.