Stool color is generally influenced by what you eat as well as by the amount of bile — a yellow-green fluid that digests fats — in your stool. As bile pigments travel through your gastrointestinal tract, they are chemically altered by enzymes, which change the pigments from green to brown.
Yellow Stool
Yellow stool can indicate that food is passing through the digestive tract relatively quickly. Yellow stool can be found in people with GERD (gastroesophageal reflux disease). Symptoms of GERD include heartburn, chest pain, sore throat, chronic cough, and wheezing. Symptoms are usually worse when lying down or bending. Foods that can worsen GERD symptoms include peppermint, fatty foods, alcohol, coffee, and chocolate.
Yellow stool can also result from insuffient bile output. Bile salts from the liver gives stool its brownish color. When bile output is diminished, it often first appears as yellow stool. If there is a greater reduction in bile output, stool lose almost all of its color, becoming pale or grey.
If the onset is sudden, yellow stool can also be a sign of a bacterial infection in the intestines.
Green
Food is moving through the large intestine too quickly, such as due to diarrhea. As a result, bile doesn't have time to break down completely.
Green leafy vegetables, green food coloring, such as in Kool-Aid or popsicles, iron supplements.
If this happens commonly I would suggest talking to your gastroenterologist only they can diagnose the cause of the issue.
Good luck.
Hector
It may not be not unreasonable to suspect Crohns or similar autoimmune cause, given the timing.
Check up on Crohns and / or irritable bowel.
I too am having this problems, on week 13 of triple tx, have detected Und since week four, but still get freaked out when I see light colored poo as it brings back memories of before when the hep was active and my poo was white, but with these meds affecting me the way they do I just want to see what the end result will be, did talk to dr. about this , said nothing to worry about now, the med jack with a lot of stuff during treatment.