Stomach aches have dozens of possible causes, ranging from something as simple as eating too fast to serious conditions that need emergency care. Most episodes are temporary and tied to diet, stress, or a mild infection. But recurring or severe pain, especially when paired with other symptoms, can signal something that needs medical attention. Where the pain sits, how long it lasts, and what else is happening in your body all help narrow down what’s going on.
The Most Common Everyday Causes
The stomach aches most people experience come and go without much drama. Gas and bloating from swallowing air or eating gas-producing foods can cause sharp, crampy pain that moves around the abdomen. Constipation builds pressure in the lower belly that can feel dull and persistent. Viral gastroenteritis, often called the stomach flu, brings on nausea, vomiting, diarrhea, and cramping that typically resolves within a few days.
Indigestion, also called functional dyspepsia, is another frequent culprit. It causes a burning or uncomfortable fullness in the upper abdomen, often after meals, without any visible damage to the digestive tract. Acid reflux works similarly: stomach acid backs up into the esophagus and causes a burning sensation in the upper stomach and chest. Both are more likely after large meals, spicy or fatty foods, or eating close to bedtime.
Food Intolerance vs. Food Allergy
If your stomach hurts after eating specific foods, you’re likely dealing with either an intolerance or an allergy, and the difference matters. A food intolerance affects only the digestive system and causes less serious symptoms like bloating, gas, cramps, or diarrhea. The most common example is lactose intolerance, where your body lacks the enzyme needed to break down the sugar in dairy products. Fructose and gluten sensitivities work similarly.
A true food allergy is an immune system reaction. Even tiny amounts of the trigger food can cause symptoms that go well beyond the stomach, including hives, swelling, and in severe cases, a life-threatening reaction called anaphylaxis. If your symptoms are limited to digestive discomfort that shows up 30 minutes to a few hours after eating, intolerance is the more likely explanation.
How Stress Causes Real Stomach Pain
Stress-related stomach aches aren’t imaginary. Your gut and brain communicate constantly through a dense network of nerves, and stress disrupts that communication in measurable ways. It changes how quickly food moves through the digestive tract, alters the permeability of the gut lining, and shifts the balance of gut bacteria. These changes can make the nerve endings in your intestines abnormally sensitive, so normal digestive activity starts to register as pain.
Research has shown that stress reduces the gut’s production of certain calming compounds, including lipopeptides that contain GABA, a chemical that normally damps down nerve signaling. People with irritable bowel syndrome (IBS) have lower levels of these compounds in their stool compared to healthy volunteers. This helps explain why anxiety and chronic stress so reliably trigger cramping, bloating, and changes in bowel habits, and why relaxation techniques can genuinely reduce gut symptoms.
Pain Medications That Hurt Your Stomach
Over-the-counter painkillers like ibuprofen, aspirin, and naproxen are among the most common medication-related causes of stomach pain. These drugs work by blocking inflammation, but they also weaken the protective mucus lining of the stomach. About 50% of people who take these painkillers regularly develop erosions in the stomach lining, and 15% to 30% develop actual ulcers visible on an endoscopy. Clinically significant problems, including bleeding or perforation, occur in roughly 3% to 4.5% of regular users.
The risk goes up the longer you take them and the higher the dose. If you notice burning or gnawing pain in your upper stomach during a course of these medications, that’s the most likely explanation. Taking them with food helps somewhat, but it doesn’t eliminate the risk.
IBS vs. Inflammatory Bowel Disease
Both IBS and inflammatory bowel disease (IBD) cause recurring stomach pain, but they’re fundamentally different conditions. IBS is a syndrome, a collection of symptoms without visible damage to the intestines. It causes cramping, bloating, and alternating diarrhea and constipation, but it doesn’t increase your risk of colon cancer and rarely requires surgery. The underlying problem is irregular muscle contractions in the gut wall and oversensitive nerve endings. Diagnosing it requires at least 12 weeks of abdominal discomfort over the past year, along with pain that improves after a bowel movement or coincides with changes in stool frequency or consistency.
IBD, which includes Crohn’s disease and ulcerative colitis, causes destructive inflammation that’s visible on imaging and during colonoscopy. It can permanently damage the intestines. Key warning signs that point toward IBD rather than IBS include unexplained weight loss, bloody stool, anemia, and fever. IBD does raise colon cancer risk over time.
Bacterial Infections and H. Pylori
A specific bacterium called H. pylori is responsible for the majority of stomach ulcers worldwide. It burrows into the stomach’s mucus lining, weakens the protective barrier, and stimulates excess acid production while suppressing the hormones that would normally keep acid in check. The infection is more common in developing countries but affects roughly 20% of white Americans, 54% of Black Americans, and 60% of Hispanic Americans.
Most people with H. pylori have no symptoms at all. When symptoms do appear, they typically include a gnawing or burning pain in the upper abdomen that’s worse on an empty stomach, nausea, loss of appetite, and bloating. A simple breath test or stool test can detect the infection, and a course of antibiotics combined with acid-reducing medication clears it in most cases.
Where It Hurts Tells You a Lot
The location of your pain is one of the most useful clues for figuring out what’s causing it. Pain in the upper middle abdomen points toward acid reflux, gastritis, stomach ulcers, or pancreatitis. Upper right pain is strongly associated with gallbladder problems, including gallstones and gallbladder inflammation. Upper left pain can involve the spleen or, again, gastritis and ulcers.
Pain around the belly button often comes from the small intestine or the early stages of appendicitis, which classically starts near the navel and migrates to the lower right abdomen over several hours. Lower right pain that intensifies with movement or pressure is the hallmark of appendicitis. Lower left pain in adults over 40 frequently signals diverticulitis, where small pouches in the colon wall become inflamed or infected. Pain low and centered in the pelvis can indicate bladder infections, urinary tract infections, or gynecological causes like endometriosis or ovulation pain.
Causes Specific to Women
Several conditions that cause abdominal pain affect only women. Endometriosis, where tissue similar to the uterine lining grows outside the uterus, can cause chronic pelvic and lower abdominal pain that often worsens around menstruation. Ovulation pain (sometimes called mittelschmerz) produces a sharp twinge on one side of the lower abdomen mid-cycle and is completely harmless, though it can be startling if you’re not expecting it.
An ectopic pregnancy, where a fertilized egg implants outside the uterus, causes sharp lower abdominal pain that can become a medical emergency if the fallopian tube ruptures. Any sudden, severe lower abdominal pain in a woman of reproductive age warrants urgent evaluation.
Signs You Need Emergency Care
Most stomach aches resolve on their own, but certain patterns demand immediate attention. Seek emergency care if pain is severe enough to prevent you from functioning normally, if you’re vomiting repeatedly and can’t keep liquids down, or if you’re unable to have a bowel movement and the pain is escalating. Abdominal pain accompanied by fever, bloody vomit or stool, or a rigid abdomen that’s painful to touch suggests something that may need surgical intervention.
If you’ve had abdominal surgery in the past, pay extra attention to new pain. Scar tissue can cause bowel obstructions months or years later. And if the pain resembles something you’ve experienced before but feels distinctly worse or different this time, that change itself is a reason to be evaluated promptly.