Lower abdominal pain most often comes from the intestines, which take up the majority of space in the lower abdomen. But the urinary tract, reproductive organs, and even muscles in the area can all be sources. The cause can range from something minor like trapped gas to a surgical emergency like appendicitis, so the location, quality, and timing of the pain all matter.
How Pain Location Narrows the Cause
Where you feel the pain is one of the strongest clues to what’s causing it. Right-sided lower abdominal pain points toward the appendix, the end of the small intestine, or the right ovary in women. Left-sided pain is more commonly linked to the colon, particularly diverticulitis. Pain that sits in the center or doesn’t clearly favor one side often involves the bladder, uterus, or a general intestinal issue like irritable bowel syndrome.
The type of pain matters too. Deep, dull, crampy pain that’s hard to pinpoint usually comes from the organs themselves stretching or contracting. This kind of pain often comes with nausea, sweating, or restlessness. Sharp, well-localized pain that gets worse when you move, cough, or press on the area typically means the lining of the abdominal cavity has become irritated, which is a more urgent sign. People with this type of pain tend to lie very still rather than shifting around.
Intestinal Causes
Because the small and large intestines dominate the lower abdomen, they’re responsible for the largest share of pain in this area.
Irritable bowel syndrome (IBS) is one of the most common chronic causes. It produces cramping, bloating, and changes in bowel habits that tend to come and go over months or years. The pain often eases after a bowel movement.
Inflammatory bowel disease (IBD), which includes Crohn’s disease and ulcerative colitis, causes inflammation in the intestinal wall. Unlike IBS, IBD involves actual tissue damage and can produce bloody stool, weight loss, and fatigue alongside the pain.
Diverticulitis is a leading cause of lower left abdominal pain, accounting for the primary symptom in about 70% of patients with the condition. Small pouches that form in the colon wall, most often on the left side, can trap bacteria and become inflamed. The pain is typically crampy and may come with fever, bloating, constipation, or changes in bowel habits. Risk factors include obesity, smoking, alcohol use, and a diet high in red meat, particularly beef and lamb. Age increases the likelihood, but younger adults can develop it too.
Less common intestinal causes include bowel obstructions, hernias that trap a loop of intestine, and infectious gastroenteritis from bacteria, viruses, or parasites.
Appendicitis
Appendicitis deserves its own section because it’s one of the most important causes to recognize quickly. The classic pattern is pain that starts as a vague ache around the belly button, then migrates over several hours to the lower right abdomen. The pain tends to sharpen and intensify, and it gets worse with coughing, walking, or any movement that increases pressure inside the abdomen.
Other common symptoms include loss of appetite, nausea (with or without vomiting), and a low-grade fever, present in roughly 40% of patients at the time they’re seen. Some people also notice increased urinary frequency. A hallmark feature is tenderness at a specific spot about two inches inward from the front of the right hip bone, along an imaginary line toward the belly button. Pain that worsens when you extend your right hip or flex your right thigh against resistance can also signal that an inflamed appendix is irritating nearby muscles.
Urinary Tract Causes
The bladder sits in the lower center of the abdomen, and infections here are extremely common, especially in women. A urinary tract infection typically produces a burning sensation during urination, a frequent or urgent need to go, and aching pressure in the lower abdomen. Cloudy or foul-smelling urine is another telltale sign.
Kidney stones can also send pain into the lower abdomen and groin as a stone travels down the ureter toward the bladder. This pain tends to come in intense waves, shifting location as the stone moves. You may notice pink, red, or brown urine, difficulty urinating, or only passing small amounts at a time. If a stone triggers an infection, fever and chills may develop alongside the pain.
Reproductive Causes in Women
The uterus, ovaries, and fallopian tubes all sit in the lower abdomen, making gynecological conditions a major category of pain for women.
Ovarian cysts are one of the most frequent causes of acute pelvic pain in younger women. Functional cysts form as a normal part of the menstrual cycle and usually resolve on their own, but when one ruptures or bleeds, it can cause sudden, sharp one-sided pain.
Pelvic inflammatory disease (PID) is among the most common causes of acute pelvic pain in sexually active women. It involves infection and inflammation of the reproductive organs and can cause deep, bilateral lower abdominal pain, abnormal discharge, fever, and pain during intercourse.
Endometriosis more often causes chronic, cyclic pain that tracks with the menstrual cycle, though acute complications like a ruptured endometrioma can produce sudden severe pain. Over time, endometriosis can also contribute to urinary tract obstruction or bowel problems.
Ectopic pregnancy is the most dangerous reproductive cause. It occurs when a fertilized egg implants outside the uterus, most often (97% of cases) in a fallopian tube. This is a life-threatening emergency that typically causes one-sided lower abdominal pain, sometimes with vaginal bleeding and lightheadedness. Any woman of reproductive age with sudden lower abdominal pain and a missed or unusual period should consider this possibility seriously.
Reproductive Causes in Men
Men can experience lower abdominal pain from conditions that don’t always seem connected to that area. Prostatitis, or inflammation of the prostate gland, often produces a deep ache in the lower abdomen or pelvis along with urinary symptoms like frequency, urgency, or a weak stream. Inguinal hernias, where tissue pushes through a weak spot in the abdominal wall near the groin, cause pain that worsens with lifting, coughing, or straining. Testicular torsion, though primarily felt in the scrotum, can refer pain upward into the lower abdomen, particularly in younger males.
How the Cause Gets Identified
When the source of lower abdominal pain isn’t obvious from the symptoms alone, imaging is usually the next step. A CT scan is the go-to choice for undifferentiated abdominal pain, especially in older adults, people with weakened immune systems, or anyone with severe or uncontrolled pain. Ultrasound is preferred when a gynecological cause is suspected, and it’s the first-line option for pregnant patients and children to avoid radiation exposure. For kidney stone evaluation in pregnant women or those with urinary stents, ultrasound is also the starting point.
If an initial ultrasound comes back normal but suspicion remains high for something like a tubo-ovarian abscess, CT or MRI may follow.
Signs That Need Urgent Attention
Certain features of lower abdominal pain signal that something serious may be happening. A rigid abdomen that hurts more when you release pressure than when you press down suggests peritoneal irritation. Pain that wakes you from sleep, prevents you from walking upright, or comes with a fever above 101°F warrants prompt evaluation. Low blood pressure or a rapid heart rate in the setting of abdominal pain are strong warning signs, particularly for appendicitis or internal bleeding.
For women of reproductive age, lower abdominal pain combined with a missed period, vaginal bleeding, or dizziness raises concern for ectopic pregnancy. In men and boys, sudden-onset testicular and lower abdominal pain together may indicate torsion, which requires treatment within hours to save the testicle.