Evaluating the safety of oral methylene blue during swallowing assessment: a systematic review

ConclusionSerious AEs due to oral administration of MB are rare (n = 3, 0.16%). MB-related non-serious AEs are mild, self-limiting, and show a dose-related trend. These findings indicate that it is safe to use small amounts of MB as a food dye during swallowing examinations.
Source: European Archives of Oto-Rhino-Laryngology - Category: ENT & OMF Source Type: research