My poo has been dark green for 3/ weeks now but i was taking vitamins for my hair they were from kaiser i stopped taking hem a week ago?

Food/ fast transit: If the stool was loose, the reason for green stool could be too rapid a transit time in the gut. Eating green leafy vegetables can lead to green stool. Green cabbage, lettuce, peas, cabbage, spinach, broccoli, green salad, green leaves, celery & green beans as well as food that contains green food coloring can lead to green stool. I don’t know about the medication you were taking.

Green stool color: Color of stool varies with foods, speed of emptying of the GI tract, medications & supplements ingested, gut flora (unique for each individual), additives (like blood), subtractions (like absent bile), infection, inflammation, & other factors. If the green color is unusual for you & persists despite stopping the vitamins in question, or is accompanied by other symptoms, see your doctor please.