Abdominal pain is one of the most common reasons adults visit an emergency department, accounting for roughly 10% of all non-injury ER visits. The causes range from completely harmless to life-threatening, and the location, timing, and quality of the pain are often the best early clues to what’s going on. About 17% of ER visits for abdominal pain turn out to involve a serious diagnosis like appendicitis, gallstones, or kidney stones. The rest are typically caused by less dangerous conditions like gastritis, constipation, or viral infections.
Why Location Matters
Your abdomen contains dozens of organs packed into a relatively small space, and each one produces pain in a somewhat predictable zone. Paying attention to where the pain is strongest helps narrow the possibilities significantly.
Upper right side: This is gallbladder and liver territory. Gallstones, gallbladder inflammation, and hepatitis are the classic culprits. Kidney stones and kidney infections on the right side can also land here, and occasionally a lower lung problem like pneumonia or a blood clot in the lung produces pain that feels like it’s coming from the abdomen.
Upper left side: Stomach problems dominate this area, including gastritis (inflammation of the stomach lining), acid reflux, and ulcers. Pancreatitis, an inflammation of the pancreas, often causes intense pain here that radiates straight through to the back. Heart problems can also masquerade as upper left abdominal pain, particularly in older adults.
Lower right side: The most concerning cause here is appendicitis, which classically starts as a vague ache around the belly button and migrates to the lower right over several hours. Inflammatory bowel disease, irritable bowel syndrome, kidney stones, and in women, ovarian problems or ectopic pregnancy also cause pain in this region.
Lower left side: Diverticulitis, where small pouches in the colon wall become inflamed or infected, is one of the most common causes of lower left pain in adults over 40. Inflammatory bowel disease, irritable bowel syndrome, constipation, kidney stones, and gynecologic conditions round out the list.
Common Digestive Causes
Most abdominal pain originates in the digestive tract and resolves without serious intervention. Gastroenteritis (a stomach bug) causes crampy, widespread pain along with nausea, vomiting, or diarrhea and typically clears within a few days. Constipation is an underappreciated cause of significant abdominal discomfort, producing bloating and cramping that can feel alarming but improves once the bowels move. Gas trapped in the intestines can mimic sharper, more localized pain and sometimes gets mistaken for something more serious.
Irritable bowel syndrome affects an estimated 10 to 15% of adults and causes recurring cramping, bloating, and changes in bowel habits without any visible damage to the intestines. Inflammatory bowel disease, which includes Crohn’s disease and ulcerative colitis, produces similar symptoms but involves actual inflammation and tissue damage that shows up on imaging or colonoscopy. Peptic ulcers, caused by either a bacterial infection or long-term use of anti-inflammatory painkillers, create a burning or gnawing pain in the upper abdomen that often worsens on an empty stomach.
Gallstones, Kidney Stones, and Pancreatitis
Gallstones are one of the leading serious diagnoses behind abdominal pain. They produce episodes of intense upper right pain, often after eating fatty meals, that can last anywhere from 30 minutes to several hours. If a stone blocks the bile duct or the gallbladder becomes infected, the pain becomes constant and is usually accompanied by fever.
Kidney stones cause a distinctive pain pattern: sudden, severe pain in the flank or side that radiates toward the groin. The pain comes in waves as the stone moves through the urinary tract. Many people with kidney stones also notice blood in their urine or feel a persistent urge to urinate.
Pancreatitis tends to produce severe upper abdominal pain that bores through to the back and worsens after eating. Heavy alcohol use and gallstones are the two most common triggers. The pain is often intense enough to send people to the emergency room, and acute episodes sometimes require hospitalization.
Appendicitis: A Pain Pattern Worth Knowing
Appendicitis is one of the most common surgical emergencies, and recognizing its typical progression can be genuinely useful. The pain usually begins as a dull, hard-to-locate ache near the belly button. Over 6 to 24 hours, it migrates to the lower right abdomen and becomes sharper and more constant. Loss of appetite is nearly universal, and many people experience nausea or vomiting after the pain starts (not before). A low-grade fever often develops as the inflammation worsens.
Not every case follows the textbook pattern. In pregnant women, the appendix gets pushed higher as the uterus grows, so the pain may appear in an unusual location. In young children, the symptoms are often vague and nonspecific, making diagnosis harder.
Causes Specific to Women
Several gynecologic conditions cause lower abdominal or pelvic pain that can be difficult to distinguish from digestive problems. Menstrual cramps and ovulation pain (mittelschmerz) are the most common and least dangerous.
Ectopic pregnancy, where a fertilized egg implants outside the uterus, usually in a fallopian tube, is the most urgent concern. It produces localized pain on one side of the lower abdomen along with a positive pregnancy test. If the tube ruptures, the pain becomes sudden and severe and spreads across the entire abdomen. Any woman of reproductive age with lower abdominal pain and a missed period should have a pregnancy test to rule this out.
Ovarian torsion occurs when an ovary twists on its blood supply, cutting off circulation. It causes sudden, intense one-sided pelvic pain, often with nausea and vomiting. Ovarian cysts that rupture or grow large enough to press on surrounding structures produce similar symptoms, though typically less severe. Pelvic inflammatory disease, an infection of the reproductive organs usually linked to sexually transmitted bacteria, causes lower abdominal tenderness on both sides along with abnormal discharge and sometimes fever.
Causes That Don’t Start in the Abdomen
Some of the most dangerous causes of abdominal pain actually originate outside the abdomen entirely. A heart attack, particularly in women and older adults, can present as upper abdominal pain rather than the classic chest tightness. Pneumonia in the lower lobes of the lungs frequently causes upper abdominal pain because the inflamed lung tissue irritates the diaphragm. A pulmonary embolism (blood clot in the lung) can do the same.
Metabolic conditions also produce abdominal pain. Diabetic ketoacidosis, a dangerous complication of uncontrolled diabetes, often causes diffuse abdominal pain alongside extreme thirst, frequent urination, and confusion. Sickle cell disease can trigger abdominal crises. Even some toxic exposures, including heavy metal poisoning, black widow spider bites, and scorpion stings, present primarily as abdominal pain.
Why Abdominal Pain Feels Different Depending on the Cause
The quality of your pain reflects which type of nerve fibers are sending the signal. Internal organs like the intestines, gallbladder, and kidneys are wired with slow-conducting nerve fibers that produce a dull, diffuse, hard-to-pinpoint ache. This is why early appendicitis feels like a vague discomfort “somewhere around the belly button” rather than a precise spot. This type of deep organ pain is often described as crampy, squeezing, or pressure-like, and it tends to feel more unpleasant and nauseating than surface pain.
Once inflammation spreads to the abdominal wall lining (the peritoneum), faster nerve fibers take over, and the pain becomes sharp, well-localized, and worse with movement. That transition from vague to precise is actually a useful clinical clue: it often signals that a condition is progressing and may need more urgent attention.
Referred pain adds another layer of confusion. The brain sometimes misinterprets signals from internal organs as coming from a different body part that shares the same nerve pathways. This is why gallbladder inflammation can cause pain in the right shoulder, and why a kidney stone in the flank can radiate to the groin.
Warning Signs That Need Urgent Attention
Most episodes of abdominal pain are self-limiting. But certain features signal something potentially dangerous:
- Rigid or board-like abdomen that hurts when you press on it and hurts more when you let go (rebound tenderness)
- Pain with fainting or near-fainting, which can indicate internal bleeding or a ruptured organ
- Vomiting blood or green bile, which suggests a bowel obstruction or upper GI bleed
- Severe pain with fever, pointing toward infection or inflammation that may need intervention
- Signs of gastrointestinal bleeding like black, tarry stools or bright red blood in the stool
- A visibly distended abdomen, especially if it’s tense and tender
- Severe pain that came on suddenly, sometimes described as the worst pain of your life, which can indicate a ruptured aneurysm, perforated organ, or torsion
How Abdominal Pain Gets Diagnosed
When the cause isn’t obvious from your symptoms and a physical exam, imaging is usually the next step. A CT scan of the abdomen and pelvis with contrast dye is the preferred first-line test for most types of non-specific abdominal pain, according to the American College of Radiology. It can identify a wide range of problems including appendicitis, diverticulitis, bowel obstruction, abscesses, kidney stones, and tumors in a single scan.
Ultrasound is less comprehensive but plays an important role in specific situations. It’s the go-to choice for pregnant women because it avoids radiation exposure. It’s also the first test ordered when gallbladder disease is the primary concern and is useful for evaluating gynecologic causes like ovarian cysts or ectopic pregnancy. Its main limitation is that intestinal gas and body habitus can block the view of deeper structures, making it less reliable for a broad abdominal survey.
Blood tests, urine tests, and pregnancy tests fill in gaps that imaging can’t always answer, particularly for metabolic causes, infections, and early pregnancy-related conditions.