Why do I get stomach pain after eating dairy?

Stomach pain after dairy is usually lactose intolerance: the small intestine makes less lactase - the enzyme that splits milk sugar - than the dairy load demands, so lactose reaches the colon intact, where bacteria ferment it into gas and draw in water. NIDDK lists the result: crampy belly pain, bloating, gas, and loose stools, starting 30 minutes to two hours after dairy. Most adults worldwide have some degree of lactase decline - it is the genetic default, and keeping high lactase into adulthood is the exception. Confirming it at home: cut dairy strictly for two weeks and watch symptoms clear, then reintroduce a glass of milk and watch them return - that challenge is how most people settle it, and providers accept the history. A hydrogen breath test exists when the answer matters formally. Living with it: lactose-free milk and lactase tablets genuinely work; hard cheeses and yogurt with live cultures are naturally low in lactose and often tolerated; and small amounts spread through the day sit better than one big glass. Watch calcium and vitamin D intake if dairy shrinks. Pain after dairy that comes with vomiting, blood in stool, weight loss, or pain that wakes you at night is not simple intolerance - that pattern gets a provider, since it points at inflammation rather than enzyme shortfall. Pymander is a free AI doctor, 24/7 by text. Describe what you ate and when the pain starts, and it can help you test the theory.