Lower stomach pain has dozens of possible causes, ranging from something as simple as trapped gas to conditions that need prompt medical attention. The most common culprits are gastrointestinal issues like gastroenteritis, irritable bowel syndrome, and constipation, which together account for the majority of cases seen in primary care. Where exactly the pain is, what it feels like, and what other symptoms come with it can narrow the list considerably.
What’s Actually Down There
Your lower abdomen is packed with organs, and knowing which ones sit where helps make sense of the pain. On the right side, you’ll find your appendix, the beginning of your large intestine (the cecum), and your right ureter, which drains urine from your kidney to your bladder. On the left side, the descending and sigmoid portions of your colon dominate, along with the left ureter. Your bladder sits right in the middle, low in the pelvis. If you have female reproductive organs, the uterus, ovaries, and fallopian tubes are also in this region, which is why it can be genuinely difficult to tell intestinal cramps from menstrual cramps.
Digestive Causes
Digestive problems are the most frequent explanation for lower abdominal pain. A stomach bug (gastroenteritis) tops the list, causing crampy pain alongside diarrhea, nausea, or vomiting. It usually resolves within a few days on its own. Constipation is another extremely common cause, especially on the left side, where stool builds up in the sigmoid colon. The pain tends to feel dull and pressure-like, and it eases after a bowel movement.
Irritable bowel syndrome (IBS) affects roughly 3 to 13 percent of people who see a doctor for abdominal pain. It causes recurring cramping, bloating, and changes in bowel habits without any visible damage to the intestines. The pain often improves or worsens around meals and bowel movements. Inflammatory bowel diseases like Crohn’s disease and ulcerative colitis cause similar symptoms but also involve inflammation that shows up on testing, and they tend to produce bloody stool, weight loss, or fatigue over time.
Diverticulitis deserves special attention if you’re over 40 and the pain is on your lower left side. Small pouches in the colon wall become inflamed or infected, producing steady, localized pain that often comes with fever and a change in bowel habits. About 3 percent of people who visit a doctor for abdominal pain turn out to have diverticulitis, and it typically requires treatment.
Urinary Tract Problems
A bladder infection, the most common type of urinary tract infection, frequently causes pain or discomfort in the lower abdomen, right behind the pubic bone. The telltale signs are a burning sensation when you urinate, frequent urgent trips to the bathroom even when little comes out, and cloudy or strong-smelling urine. Bladder infections are caused by bacteria and are far more common in women, though men get them too.
Kidney stones can also produce lower abdominal pain, though the pain more classically starts in the back or side and radiates downward toward the groin as the stone moves through the ureter. The pain tends to come in intense waves. Worth noting: about 16 percent of people with confirmed kidney stones don’t have blood in their urine, so a clean urine test doesn’t completely rule them out.
Reproductive Causes in Women
For women, lower abdominal pain has a whole additional category of possible explanations. Menstrual cramps are the most obvious one, and some degree of cramping around your period is normal. But pain that’s severe enough to interfere with daily life, or that occurs outside your period, can signal something else.
Ovulation pain (sometimes called mittelschmerz) happens mid-cycle when an egg is released. It’s typically a brief, one-sided twinge, though some women feel it more intensely. Ovarian cysts, fluid-filled sacs on the ovary, can cause a dull ache on one side that comes and goes. Most cysts resolve on their own, but a ruptured cyst causes sudden, sharp pain that can be severe.
Endometriosis occurs when tissue similar to the uterine lining grows outside the uterus. It produces chronic pelvic pain that often worsens during periods, sex, or bowel movements. Pelvic inflammatory disease, an infection of the reproductive organs usually linked to sexually transmitted bacteria, causes lower abdominal pain along with unusual discharge, fever, or pain during sex. Uterine fibroids, benign growths in the uterine wall, can create a sensation of pressure or heaviness along with heavy periods.
Causes More Common in Men
Inguinal hernias account for 75 percent of all hernias, and they overwhelmingly affect men. About one in four men will develop one at some point. A hernia happens when part of the intestine pushes through a weak spot in the abdominal wall near the groin, creating a visible bulge that may ache or burn. The bulge often becomes more noticeable when you stand, cough, or strain. Sometimes a groin hernia can extend down into the scrotum, causing swelling there. Unlike a muscle strain, a hernia won’t go away with rest and needs medical evaluation.
Prostatitis, inflammation of the prostate gland, can cause pain in the lower abdomen, groin, or perineum along with urinary symptoms like urgency, frequency, or difficulty starting the stream. It can be caused by a bacterial infection or, more commonly, by nonbacterial inflammation that’s harder to pin down.
Muscle Strain
Not all lower abdominal pain comes from your organs. A strained abdominal muscle can mimic internal problems convincingly. The key difference is that muscle pain gets worse with specific movements: coughing, sneezing, laughing, getting up from a seated position, or doing vigorous exercise. It may also come with bruising, swelling, or visible muscle spasms. A simple test your doctor might use is pressing on the tender spot while you lift your head or legs off the table. If the pain increases with that maneuver, it’s more likely coming from the abdominal wall itself rather than from an organ underneath.
Muscle strains improve with rest over days to weeks. Hernias, by contrast, produce a bulge and can cause constipation, nausea, or vomiting, symptoms a muscle strain doesn’t cause.
When the Pain Needs Urgent Attention
About 1 in 10 people who see a doctor for abdominal pain have something that needs prompt treatment, like appendicitis, diverticulitis, or a gallbladder or pancreatic problem. Appendicitis follows a recognizable pattern: it often starts as a vague, nagging pain around the belly button with a loss of appetite, then migrates to the right lower abdomen over the course of 12 to 24 hours, becoming progressively more severe. The pain gets worse when you move, cough, or take deep breaths. Fever, nausea, vomiting, and an inability to pass gas may follow.
Seek emergency care if your lower abdominal pain is severe enough to keep you from functioning normally, is accompanied by vomiting that won’t stop, comes with a fever and worsening tenderness, or involves an inability to have a bowel movement alongside escalating pain. Pain that is sudden and sharp, especially after a missed period, could indicate an ectopic pregnancy, which is a medical emergency.
How Doctors Figure Out the Cause
In about one-third of cases, the exact cause of abdominal pain is never pinpointed, often because the pain resolves on its own before a diagnosis is made. When it doesn’t resolve, your doctor will start with a physical exam, pressing on your abdomen to check for tenderness, masses, or signs of inflammation. A urine test is standard to check for infection or blood.
If imaging is needed, ultrasound is often the first step because it’s fast, radiation-free, and good at spotting problems like ovarian cysts, kidney stones, and sometimes appendicitis. For lower abdominal pain that remains unclear, a CT scan with contrast is the most informative test, offering detailed views of the intestines, reproductive organs, and surrounding structures. For pregnant patients, ultrasound and MRI are preferred to avoid radiation exposure.
The type of pain matters for the workup. Crampy pain that comes in waves points toward something in the intestines or ureters. Constant, localized pain that worsens with movement suggests inflammation or infection of a specific organ. Dull, diffuse pain is harder to localize and may take longer to diagnose.