The parents of a 7-month-old girl brought their daughter for immediate medical attention after she passed bright green-colored stool. For the past 24 hours, the child had mild fussiness and a low-grade fever (temperature, 38.1°C [100.6°F]); she also had vomiting and mild diarrhea, with yellow-colored stools. The mother was advised to begin small, frequent feedings of oral rehydration solution with gradual return to the baby's normal diet, as tolerated. Over the next 12 hours, the vomiting and fussiness decreased and the fever resolved, but the mild diarrhea persisted and stools turned bright green. The parents denied giving the child green-colored drinks or food.
The child was afebrile and appeared well-hydrated, bright, and cheerful. Abdominal findings were normal.
When assessing the cause of GI symptoms in children, an abnormal stool can often be a helpful clue.1 As described in a recent Photoclinic case in which an infant taking cefdinir(Drug information on cefdinir) passed bright red stool, multiple products can cause stool discoloration.2 Causes of green stool include large amounts of green, leafy vegetables (such as spinach); green artificial food coloring (found in Popsicles, Kool-Aid, or gelatin); medications (eg, iron supplements, indomethacin, medroxyprogesterone(Drug information on medroxyprogesterone), and mercurous chloride [once used as a laxative]); and rapid food passage with decreased colonic transit time.3
In this child, decreased transit time seemed to be the only feasible cause. However, because of the bright green color of the stool, the possibility of food coloring was explored further. The mother again denied any intake of green-colored foods, but she had fed the infant grape-flavored Pedialyte. This purple- colored drink contains Food, Drug and Cosmetic (FD&C) Blue No. 1 and Red No. 40. Blue No. 1 (also known as Brilliant Blue FCF) is a synthetic dye derived from coal tar(Drug information on coal tar) that has been used for many years as an additive to color jellies, condiments, syrups, candies, beverages, medications, and cosmetics (such as soaps and shampoos). There is no natural blue coloring in use in the United States. Thus, foods that are not naturally blue or green (eg, Fruit Loops cereal) often contain Blue No. 1.
Blue No. 1 is poorly absorbed from the GI tract in healthy persons and is generally considered safe. It has been added to enteral feeding solutions of critically ill patients to detect pulmonary aspiration; however, in this setting, serious adverse effects, including hypotension and acidosis, have been reported.4 If consumed in sufficient quantity, Blue No. 1 can turn stools a bright, fluorescent green color.5 *