Drinking expired or spoiled milk can lead to uncomfortable digestive symptoms such as stomach pain, nausea, vomiting, and diarrhea. This happens because as milk spoils, bacteria like E. coli , Listeria , and Salmonella can multiply and produce toxins that upset your stomach

. Spoiled milk also contains lactic acid from fermentation, which makes it sour and harder to digest

. A small accidental sip of spoiled milk is unlikely to cause serious harm, but consuming moderate to large amounts increases the risk of food poisoning and more severe symptoms

. If symptoms like vomiting or diarrhea persist or worsen, it is advisable to consult a healthcare provider

. Milk expiration dates generally indicate quality rather than safety. Pasteurized milk, when stored properly in the refrigerator (at 38-40°F), can remain safe for several days past the printed date-typically 4-7 days after opening and up to 7 days unopened

. Signs that milk has spoiled include a sour smell, off taste, changes in color, and lumpy texture

. In summary:

• Drinking a small amount of expired milk usually causes no or mild symptoms.
• Drinking larger amounts can cause food poisoning with nausea, vomiting, stomach pain, and diarrhea.
• Spoiled milk has a sour smell, bad taste, and may be lumpy.
• Proper refrigeration and checking for spoilage signs help avoid drinking bad milk.
• If symptoms after drinking spoiled milk are severe or persistent, seek medical advice.

This information is based on food safety and health sources and reflects typical outcomes of consuming expired milk