Spoiled milk is milk that has gone bad, either because it’s well past its printed date or because it was accidentally left unrefrigerated. Drinking a small sip of spoiled milk is unlikely to cause symptoms beyond a bad taste. However, drinking larger amounts of spoiled milk can cause stomach distress resulting in abdominal cramping, vomiting, and diarrhea, similar to a food-borne illness. Symptoms caused by drinking spoiled milk usually resolve within 12-24 hours. The key is to prevent dehydration by sipping small amounts of fluid that contain sugar or electrolytes, such as popsicles and oral rehydration fluids. It is important to avoid taking any medication to stop diarrhea because anti-diarrheal medications decrease the elimination of whatever caused the problem. If you or someone you know has ingested spoiled milk, rinse the mouth thoroughly and give them some water to drink. If problems start or you have questions, call a poison control center right away.

In summary, drinking spoiled milk can cause digestive distress, such as vomiting, abdominal cramping, and diarrhea. It is best to avoid drinking it in large or even moderate quantities. If you accidentally ingest a small sip of spoiled milk, it is unlikely to make you sick.