Nausea and vomiting are common during chemotherapy. But when what comes up is green or yellow and keeps returning several times a day even after taking anti-nausea (antiemetic) medicine, it is worth pausing to ask why. When the stomach is already empty yet vomiting continues, the green or yellow fluid is usually bile — a digestive juice made by the liver that flows into the upper part of the small intestine. Once the stomach's contents are gone, ongoing vomiting can bring this bile back up, giving it that characteristic color.
Bile-colored vomit by itself does not automatically mean danger. What matters more than the color is how often it happens and what else is happening alongside it. In particular, when stomach cancer has spread to the lining of the abdomen (peritoneal metastasis), the bowel can become pressed or narrowed so that food and digestive fluids cannot pass downward — a situation called bowel obstruction. In that case, oral antiemetics often bring little relief, because a pill has to travel through the digestive tract and be absorbed, which is hard to expect when the path itself is blocked.
So 'the anti-nausea medicine isn't working' can sometimes be more than a matter of switching or adding drugs — it may be a sign to check whether something has changed in the digestive tract. It is safer to tell your care team without delay if several of these appear together: a belly that grows increasingly swollen and firm, cramping pain that comes and goes in waves, both gas and stool stopping, vomit that smells like stool, or being unable to keep down even water while urine noticeably decreases. These can point to more than simple queasiness.
Another key concern with repeated vomiting is dehydration and electrolyte imbalance. Losing fluid along with sodium and potassium can leave you weaker and dizzier. At home, sipping small amounts often — sucking on ice chips or taking lukewarm water or an electrolyte drink a mouthful at a time — is usually gentler than drinking a lot at once. But if you have already vomited repeatedly and cannot keep water down, it is better to contact the hospital than to force fluids. There, fluids and antiemetics can be given by vein if needed, pooled contents can be drained through a tube, and imaging can check for a blockage.
Above all, rather than panicking over the color alone or brushing it off, note the frequency, the state of your abdomen, and your bowel and urine output, then share this at your visit — it helps greatly with the assessment. In advanced disease, easing vomiting so the day feels more comfortable is itself an important goal of care, and there is often room to adjust the medicines and methods.
This article is general information to aid understanding and does not replace an individual diagnosis or medical care. If symptoms recur or the warning signs above appear, please consult your own care team.