Stomach pain has dozens of possible causes, ranging from something as simple as eating too fast to serious conditions that need emergency care. In the United States alone, abdominal pain accounts for 5 to 10 million emergency visits every year. Most of the time, the cause is temporary and treatable, but where the pain is located, how long it lasts, and what other symptoms come with it can tell you a lot about what’s going on.
Where the Pain Is Matters
Your abdomen contains many organs packed into a relatively small space, and pain in different areas points to different sources. Upper right pain often involves the liver, gallbladder, or the upper part of the pancreas. Upper left pain is more commonly tied to the stomach, spleen, or the body of the pancreas. Lower right pain is the classic location for appendicitis, since the appendix sits in that quadrant alongside part of the colon. Lower left pain frequently involves the sigmoid colon, which is where conditions like diverticulitis develop.
Pain that’s hard to pinpoint, or that seems to radiate across the whole abdomen, is often related to the intestines, gas, or a more generalized issue like a stomach virus. Pain that starts in one place and moves can also be a clue. Appendicitis, for example, often begins as a vague ache around the belly button before shifting to the lower right side.
The Most Common Causes by Age
What’s behind your stomach pain partly depends on how old you are. In adults in their twenties and thirties, the most frequent serious causes are appendicitis, gallbladder inflammation, and pancreatitis. In people over 65, diverticulitis and gallbladder disease become more common, while kidney stones (renal colic) and appendicitis are more typical in younger adults. A large retrospective study found that nonspecific abdominal pain and kidney stones together account for nearly 60% of emergency abdominal pain diagnoses, meaning more often than not, the cause is either benign or related to a kidney stone passing through.
In children, the causes shift again. Constipation is one of the most common culprits, especially for lower abdominal pain in older kids. Urinary tract infections are surprisingly frequent in children ages one to five, particularly girls, and can cause belly pain along with burning during urination. Even strep throat can trigger stomach pain in children over two, because swallowed bacteria irritate the intestines. Emotional stress also plays a real role in school-age children, sometimes producing recurring abdominal pain with no identifiable physical cause.
Digestive Conditions That Cause Ongoing Pain
If your stomach pain keeps coming back over weeks or months, a chronic digestive condition is a likely explanation.
Acid reflux (GERD) affects up to 20% of the U.S. population. It causes a burning sensation in the upper abdomen or chest when stomach acid flows back into the esophagus. Eating large meals, lying down after eating, and consuming fatty or spicy foods can all make it worse.
Irritable bowel syndrome (IBS) is diagnosed when you’ve had abdominal pain at least once a week for three months, with symptoms that started at least six months prior, and the pain is connected to bowel movements or changes in stool frequency or appearance. IBS doesn’t cause visible damage to the gut, but it can significantly affect quality of life. If you notice rectal bleeding, blood in your stool, unexplained weight loss, or anemia alongside your pain, those suggest something other than IBS and warrant investigation.
A bacterial infection called H. pylori is another major cause of chronic stomach pain, particularly pain that feels like gnawing or burning in the upper abdomen. About 44% of adults worldwide carry this infection. While many people with H. pylori never develop symptoms, the bacteria can inflame the stomach lining and cause ulcers over time.
Food Intolerances and Dietary Triggers
Certain foods cause stomach pain not because anything is “wrong” with your digestive system, but because your body can’t fully break them down. Lactose intolerance is the most common example, affecting roughly 68% of people worldwide. When you lack enough of the enzyme that breaks down lactose (the sugar in milk), the undigested sugar passes into your colon, where gut bacteria ferment it and produce gas, bloating, cramping, and diarrhea.
Fructose, the sugar found in fruit, honey, and many processed foods, can cause similar problems. Your small intestine absorbs fructose slowly through specific transporters, and when there’s more fructose than your gut can handle, it moves into the colon and triggers symptoms. Interestingly, eating fructose alongside glucose (as happens naturally in some fruits) actually helps your body absorb it better, which is why table sugar may cause fewer problems than high-fructose corn syrup for some people.
Wheat sensitivity is more complex than many people assume. Beyond celiac disease, wheat contains several components that can trigger gut symptoms: gluten gets the most attention, but other proteins in wheat can cause low-grade inflammation in the intestinal lining, and wheat also contains fructans, a type of fermentable carbohydrate that produces gas in the same way undigested lactose does.
Medications That Irritate the Stomach
Pain relievers like ibuprofen, aspirin, and naproxen are among the most common medication-related causes of stomach pain. These drugs work by blocking the production of compounds called prostaglandins, which reduce pain and inflammation throughout the body. The problem is that those same prostaglandins also protect the stomach lining by maintaining its mucus barrier and blood flow. When you take these medications regularly, especially over weeks or months, the stomach’s protective layer thins. This can lead to inflammation, ulcers, bleeding, and in severe cases, perforation of the stomach or intestinal wall.
Taking these medications with food or using the lowest effective dose for the shortest time reduces the risk, but doesn’t eliminate it entirely.
Causes Outside the Digestive System
Not all stomach pain originates in the stomach or intestines. Several conditions in other parts of the body can present as abdominal pain, and some of them are serious.
Heart attacks don’t always feel like chest pain. Nausea, vomiting, and upper abdominal pain can be the primary symptoms, particularly in women and older adults. This happens because the heart and the gastrointestinal tract share some of the same nerve pathways, making it difficult for your brain to distinguish between the two sources. About 6.7% of people with blood clots in the lungs (pulmonary embolism) initially seek care for vague stomach symptoms rather than chest or breathing complaints.
Pneumonia, particularly in very young children and older adults, can also present with abdominal pain, nausea, and headache rather than the typical cough and fever. Diabetic ketoacidosis, a dangerous complication of diabetes, frequently causes abdominal pain along with nausea and vomiting that resolves once blood sugar and acid levels are corrected. An overactive thyroid can slow stomach emptying, leading to nausea and abdominal discomfort that may be mistaken for a digestive problem.
When Stomach Pain Is an Emergency
Most stomach pain resolves on its own or with simple treatment, but certain patterns signal something that needs immediate attention. Pain that is sudden, severe, and doesn’t ease within 30 minutes is one of the clearest red flags. Continuous severe pain paired with nonstop vomiting can indicate a life-threatening condition like a bowel obstruction, organ perforation, or a ruptured blood vessel.
Appendicitis typically starts with pain in the center of the abdomen that migrates to the lower right side, often accompanied by loss of appetite, nausea, vomiting, or fever. Pancreatitis causes pain in the middle upper abdomen that can last for days and may worsen after eating, sometimes with a rapid pulse and a swollen, tender belly. In women of reproductive age, severe abdominal pain with vaginal bleeding raises concern for an ectopic pregnancy, which requires urgent treatment.
Stomach pain accompanied by a rigid abdomen (one that feels hard and board-like when you press on it), fainting, bloody or black tarry stools, or high fever with chills also warrants emergency evaluation rather than a wait-and-see approach.