Abdominal pain is pain felt anywhere between the chest and pelvis and can originate from the gastrointestinal tract, urinary system, reproductive organs, abdominal wall, blood vessels, nerves or structures outside the abdomen. It can be acute or chronic, localised or diffuse, cramping or constant, and mild or severe. Common causes include indigestion, constipation, trapped wind, gastroenteritis, irritable bowel syndrome, urinary infection, menstrual pain and musculoskeletal problems, while more serious causes include appendicitis, bowel obstruction, gastrointestinal bleeding, gallstones, kidney stones, pancreatitis, ectopic pregnancy and major vascular or infectious disease. Because many different organs occupy a relatively small area, symptoms can overlap considerably and pain location alone does not establish the diagnosis.
The location and character of abdominal pain can provide clues about its origin. Upper abdominal pain can arise from the stomach, duodenum, gallbladder, pancreas or liver, while lower abdominal pain can arise from the bowel, bladder or reproductive organs. Right-lower abdominal pain that progressively worsens can occur with appendicitis, whereas severe central or right-upper abdominal pain lasting hours can occur with gallstones. Cramping accompanied by bloating, diarrhoea or constipation can occur with irritable bowel syndrome. Pain radiating towards the groin with urinary symptoms can occur with kidney stones. These patterns are useful clinically but are not sufficiently specific to justify self-diagnosis because different disorders can produce similar distributions.
Gastrointestinal causes are among the most frequent explanations for abdominal discomfort. Gas, constipation and indigestion can stretch or irritate the gastrointestinal tract and cause cramping, bloating or burning. Gastroenteritis can produce abdominal cramps with vomiting or diarrhoea, usually in association with infection. Irritable bowel syndrome involves recurrent abdominal pain associated with altered bowel habits and can fluctuate over time. Inflammatory bowel diseases such as Crohn's disease and ulcerative colitis can cause abdominal pain alongside diarrhoea, bleeding, weight loss and systemic symptoms. Peptic ulcer disease, gallstones, pancreatitis and bowel obstruction can cause more severe or characteristic patterns and may require specific investigations and treatment.
Urinary and reproductive systems are important alternative sources of abdominal or lower abdominal pain. Urinary tract infections may cause lower abdominal discomfort together with painful or frequent urination, while kidney stones can produce severe colicky pain that may radiate towards the groin. In people with reproductive organs, causes can include period pain, ovarian cysts, endometriosis, pelvic inflammatory disease and pregnancy-related conditions. Ectopic pregnancy is particularly important because it can cause abdominal or pelvic pain and internal bleeding and is a medical emergency. The same abdominal location can therefore represent gastrointestinal, urinary, gynaecological or pregnancy-related disease, making pregnancy status, urinary symptoms, vaginal bleeding and menstrual history clinically important.
Abdominal pain can also originate outside the digestive organs. Abdominal-wall muscles can become painful after injury or strenuous activity, while shingles can produce pain before a characteristic rash appears. Nerve irritation can produce burning or shooting pain. Lower chest or lung disorders can sometimes be perceived as upper abdominal discomfort, and heart disease can occasionally produce symptoms involving the upper abdomen rather than classic chest pain.
Conversely, anxiety or functional gastrointestinal disorders can amplify abdominal sensations through interactions between the gut and nervous system. These possibilities illustrate why abdominal pain is a symptom rather than a diagnosis. A careful history of onset, progression, location, bowel and urinary changes, vomiting, fever, bleeding, pregnancy possibility and previous conditions is usually more informative than pain intensity alone.
Some abdominal pain results from inflammation, infection, obstruction or impaired blood supply and can become dangerous rapidly. Appendicitis often begins with abdominal pain that becomes progressively worse and may move to the lower right side; if untreated, the appendix can rupture and produce severe widespread abdominal pain. Bowel obstruction can cause pain with vomiting and inability to pass stool or gas. Gastrointestinal bleeding can produce bloody or black stools or blood in vomit. Severe pancreatitis and some vascular emergencies can cause intense upper abdominal pain. These conditions cannot safely be distinguished from benign causes solely through a written symptom description and may require examination, blood tests, imaging or other investigations.
The nature of abdominal pain can sometimes reflect the underlying physiology. Hollow organs such as the intestine can generate colicky pain when muscular contractions occur against obstruction or irritation, whereas inflammation of a solid organ or surrounding lining can cause more continuous pain. Peritoneal irritation can produce marked tenderness and pain with movement or touch. Visceral pain may be poorly localised because internal organs have different sensory innervation from skin and muscles. Referred pain can occur when sensory pathways from different anatomical regions converge within the nervous system, causing the brain to interpret visceral signals as arising elsewhere. These mechanisms explain why patients may describe abdominal pain in ways that initially seem anatomically imprecise.
Urgent assessment is needed when abdominal pain is sudden or severe, is progressively worsening, causes marked tenderness, or occurs with collapse, breathing difficulty, significant bleeding, inability to pass urine or stool, persistent vomiting, or signs of severe infection. NHS guidance advises emergency assessment for sudden severe stomach pain, pain on touching the abdomen, vomiting blood, bloody or black stools, inability to urinate or pass stool or gas, breathing difficulty or collapse. Less severe but persistent or recurrent symptoms, unexplained weight loss, abnormal vaginal bleeding, persistent diarrhoea or urinary changes also warrant medical assessment. The central principle is to assess the pattern and associated features rather than assuming that common abdominal pain is benign.
