I'm an adult whose vomit turned bright yellow to bright green to clear and over night it turned blue. i haven't eaten anything blue or anything that i am aware has any intensely added dyes. i've eaten toast, rice and veggie soup, a sandwich, coffee, and p

Only from food: Blue vomit is not a naturally occurring condition. The only known cause is ingesting a food, drink or medication with blue color or dye. Because blue is a primary color, no combination of other colors will create it. If you did not then there is no other possible cause that is known so this is a complete mystery. Consult with your doctor (but undoubtedly your doctor will be equally mystified).