Many factors can lead to abdominal pain. This includes common digestive and eating conditions, such as hunger, overeating, eating spicy or greasy foods, gas, constipation, diarrhea, vomiting, indigestion, heartburn, food poisoning and food allergies.

It is commonly caused by disorders in the abdominal organs, including:

• Gastritis (inflammation of the lining of the stomach) or gastroenteritis (inflammation of the lining of the stomach and intestines, popularly misnamed "stomach flu").
  
  
• Appendicitis. Inflammation of the appendix.
  
  
• Hepatitis (inflammation of the liver) or other liver conditions.
  
  
• Esophagitis (inflammation of the esophagus) or other esophageal conditions.
  
  
• Cholecystitis. Inflammation of the gallbladder.
  
  
• Pancreatitis. Inflammation of the pancreas.
  
  
• Peritonitis. Inflammation of peritoneum, an abdominal membrane.
  
  
• Gallstones (cholelithiasis), kidney stones (nephrolithiasis) or bladder stones (cystolithiasis).
  
  
• Intestinal obstruction. Partial or complete blockage of the bowel.
  
  
• Diverticulosis (the presence of small protruding pouches in the inner lining of the intestine) and diverticulitis (inflammation of these pouches.
  
  
• Gastroesophageal reflux disease (GERD). A condition in which food and liquid back up from the stomach into the esophagus.
  
  
• Peptic ulcer. Erosion of the lining of the stomach or upper part of the small intestine by digestive juices.
  
  
• Bowel disorders, such as inflammatory bowel disease (e.g., Crohn’s disease, ulcerative colitis) or irritable bowel syndrome.
  
  
• Malabsorption conditions (inability to digest or absorb certain nutrients), including lactose intolerance, celiac disease (gluten intolerance) or metabolic disorders such as glycogen or lipid storage diseases.
  
  

Other potential causes of abdominal pain include:

• Stress or anxiety.
  
  
• An infection elsewhere in the body or a generalized infection. Examples include strep throat, pneumonia, influenza, urinary tract infections and sexually transmitted diseases.
  
  
• Straining or tearing of abdominal muscles.
  
  
• Hernia. The protruding of an organ or tissue through an abnormal opening. Types that may cause abdominal pain include hiatal hernia (protrusion of part of the stomach through an opening in the diaphragm into the chest cavity) and umbilical hernia (protrusion of part of the small intestine through a weak area in the abdominal muscles, most common in infants and painful only in some cases.
  
  
• Heart attack.
  
  
• Somatization disorder. A condition in which psychological problems cause a person to make a number of physical complaints.
  
  
• Cancer (e.g., colon, stomach, pancreatic).
  
  
• Sickle cell anemia crisis. Blockage of blood vessels by abnormally shaped blood cells.
  
  
• Cystic fibrosis. Inherited disease in which abnormal production of mucus damages organs.
  
  
• Dissecting (leaking) or ruptured abdominal aortic aneurysm.
  
  
• Abdominal migraine, also known as periodic syndrome. Condition, most common in children, marked by recurrent bouts of abdominal pain, often accompanied by nausea, loss of appetite and vomiting. Unlike other migraines, this condition seldom involves headaches, although they often develop later in life.
  
  
• Gastroparesis. Form of autonomic neuropathy (damage to the autonomic nerves, which control regulatory and other functions), most common in people with diabetes, that slows digestion.
  
  
• Parasitic infections.
  
  
• Gastrointestinal or liver pain from HIV/AIDS.
  
  
• Drug abuse. Cocaine, for example, can cause heart problems, chest pain and abdominal pain.

Less common causes of abdominal pain include:

• Colorectal polyp. Abnormal growth in the lining of the colon or rectum. These polyps are common but usually painless.
  
  
• Diabetic ketoacidosis. Emergency condition involving severe hyperglycemia and accumulation of toxic wastes (ketones) produced when fat rather than glucose is burned for energy.
  
  
• Porphyria. Group of disorders in which enzyme abnormalities impair production of the blood pigment heme and chemical precursors of heme build up in the body.
  
  
• Rectal or anal fissure. A tear in the lining of the rectum or anus.
  
  
• Intussusception. Condition in which one part of the small intestine folds into another; this rarely occurs after infancy.
  
  
• Behcet's disease. Inflammatory condition that most often causes joint pain, eye inflammation and sores in the mouth, genitals and skin, and in rare cases causes sores in the digestive tract that produce abdominal pain.

Abdominal pain may also result from chronic disorders that can cause pain through the body, such as systemic lupus erythematosus, myositis, chronic fatigue syndrome, fibromyalgia, sarcoidosis, polymyalgia rheumatica or myofascial pain syndrome.

In women, abdominal pain may also be caused by:

• Ovulation. Many women experience pain in either side of the lower abdomen around the time of ovulation. Ovulatory pain is also known as mittelschmerz.
  
  
• Menstruation and premenstrual syndrome (PMS).
  
  
• Miscarriage. Loss of a pregnancy due to natural causes.
  
  
• Ectopic pregnancy. Implantation of a fertilized egg in tissue outside the uterus.
  
  
• Endometriosis. A condition in which the cells that make up the lining of the uterus are found outside the uterine cavity.
  
  
• Uterine fibroids. Noncancerous tumors that can form in the uterus.
  
  
• Ovarian cysts. Fluid-filled structures within or on an ovary. Causes of ovarian cysts include an endocrine disorder called polycystic ovarian syndrome (PCOS).
  
  
• Pelvic inflammatory disease. Infection of the lining of the uterus, the fallopian tubes, or the ovaries.
  
  
• Ovarian cancer or other gynecologic cancers.

In men, lower abdominal pain may be caused by prostate disorders (prostatitis, benign prostatic hyperplasia, prostatodynia or cancer) or referred pain from the testicles.