Stomach pain has dozens of possible causes, ranging from something as simple as eating too fast to serious conditions that need emergency care. The location of your pain, how suddenly it started, and what other symptoms come with it are the best clues to figuring out what’s going on. Most episodes are temporary and tied to digestion, stress, or something you ate, but persistent or severe pain deserves attention.
Where It Hurts Matters
Your abdomen contains many organs packed into a relatively small space, and pain in different areas points to different problems. Upper abdominal pain, especially in the center or slightly left, often involves the stomach itself, the pancreas, or acid-related issues. Pain in the upper right side is more likely tied to the gallbladder or liver. Lower right pain raises concern about the appendix, while lower left pain in adults is most commonly caused by problems with the lower colon, particularly diverticulitis. In women, pain on either side of the lower abdomen can also come from the ovaries or fallopian tubes.
Pain that’s hard to pinpoint, or that feels like it’s “everywhere,” is more typical of gas, bloating, irritable bowel syndrome, or a stomach virus. The more precisely you can locate your pain, the easier it is to narrow down the cause.
Acid, Ulcers, and Upper Stomach Pain
A burning or gnawing pain in your upper abdomen, especially after eating, is one of the most common reasons for stomach discomfort. This is often related to excess stomach acid irritating your stomach lining or esophagus. Acid reflux (GERD) produces a burning sensation that can radiate upward into your chest, and it tends to worsen when you lie down or eat large meals.
Peptic ulcers, which are open sores in the stomach lining or the first section of the small intestine, cause a deeper, more penetrating burn. They’re caused either by a common bacterial infection (H. pylori) or by long-term use of pain relievers like ibuprofen and aspirin. These medications can erode the protective mucus layer of your stomach. Even short-term high doses of anti-inflammatory drugs can injure the stomach lining acutely, creating small erosions that stomach acid then aggravates. Chronic use does the same thing more gradually through a slow chemical reaction that wears the lining down over time.
If you regularly take over-the-counter painkillers and notice stomach discomfort developing, the medication itself is a likely culprit.
Food-Related Causes
What you eat (and how your body handles it) is behind a large percentage of stomach pain episodes. Food intolerance and food allergy are different problems, though they can feel similar. A food allergy triggers your immune system and can cause symptoms beyond your gut, including hives, swelling, or difficulty breathing. A food intolerance is a digestive issue, usually caused by missing an enzyme your body needs to break down a specific food. Lactose intolerance is the classic example: without enough of the enzyme that digests milk sugar, dairy products cause bloating, cramps, gas, and diarrhea.
Celiac disease falls somewhere in between. It involves an immune reaction to gluten, a protein in wheat and other grains, but its primary effects are digestive: pain, bloating, diarrhea, and over time, damage to the small intestine. Many people with celiac disease go years thinking they just have a “sensitive stomach” before getting diagnosed.
Food poisoning causes pain that comes on relatively quickly (usually within hours of eating contaminated food) and is almost always accompanied by nausea, vomiting, or diarrhea. It typically resolves on its own within one to three days.
Lower Abdominal Pain
Pain in the lower left abdomen in adults is most commonly caused by diverticulitis, an inflammation of small pouches that form in the colon wall. These pouches (diverticulosis) are extremely common as people age: about 5 to 10 percent of people have them by age 45, rising to as many as 80 percent by age 80. Most people with diverticulosis never have symptoms, but 10 to 20 percent develop diverticulitis at some point. The hallmark is left lower abdominal pain, often accompanied by fever. Mild cases involve localized inflammation, but severe cases can lead to complications like abscesses or perforation.
Lower right abdominal pain that started as a vague ache around your belly button and then moved rightward over several days is the textbook pattern for appendicitis. The pain tends to become sharper and more localized as the appendix becomes more inflamed. Loss of appetite, nausea, vomiting, and fever often accompany it.
Causes Specific to Women
Several gynecological conditions produce pain that feels like a stomach problem. Ovarian cysts, which are fluid-filled sacs that form on the ovaries, can cause a dull ache or sharp pain on one side of the lower abdomen. Most are harmless and resolve on their own, but a ruptured or twisted cyst causes sudden, intense pain.
Endometriosis, a condition where tissue similar to the uterine lining grows outside the uterus, causes chronic pelvic and abdominal pain that often tracks with menstrual cycles. Many women with endometriosis initially attribute their pain to normal period cramps. An ectopic pregnancy, where a fertilized egg implants outside the uterus (usually in a fallopian tube), causes severe abdominal pain and vaginal bleeding and is a medical emergency.
Stress, Gas, and Functional Pain
Not all stomach pain has a structural cause you can see on a scan. Stress and anxiety directly affect gut function. Your brain and digestive system share nerve pathways, so emotional distress can trigger cramping, nausea, and changes in bowel habits. Irritable bowel syndrome (IBS) is one of the most common causes of recurring abdominal pain, producing cramping, bloating, and alternating diarrhea and constipation without any visible damage to the intestines.
Simple gas and bloating account for a huge number of stomach pain episodes. Swallowing air (from eating quickly, chewing gum, or drinking carbonated beverages), eating high-fiber or gas-producing foods, and constipation all create pressure and discomfort that can feel surprisingly intense. This type of pain tends to be diffuse, comes in waves, and resolves after passing gas or having a bowel movement.
When Stomach Pain Is an Emergency
Most stomach pain is not dangerous, but certain patterns require immediate medical care. According to the American College of Emergency Physicians, you should seek emergency attention if the pain is sudden and severe, or if it doesn’t ease within 30 minutes. Continuous severe pain accompanied by nonstop vomiting can indicate a serious or life-threatening condition.
Acute pancreatitis produces pain in the middle upper abdomen that can last for days, sometimes starting mild and worsening after eating. It’s often accompanied by nausea, abdominal swelling and tenderness, fever, and a rapid pulse. Other red flags that warrant urgent evaluation include:
- Bloody or black stool, which can indicate internal bleeding
- Vomiting blood, even small amounts
- High fever alongside abdominal pain
- Severe right lower abdominal pain with loss of appetite and nausea (possible appendicitis)
- Severe pain with vaginal bleeding in women of reproductive age (possible ectopic pregnancy)
Abdominal pain that comes on suddenly after an injury, pain so severe you can’t stand up straight, or a rigid abdomen that’s painful to touch all warrant a trip to the emergency room rather than waiting for a scheduled appointment.