Lower abdominal pain has dozens of possible causes, ranging from a temporary muscle cramp or gas buildup to conditions that need prompt medical attention like appendicitis or an ectopic pregnancy. Where exactly you feel the pain, how it started, and what other symptoms you have all help narrow down what’s going on. In emergency rooms, the two most common diagnoses for abdominal pain are acute gastroenteritis (about 11% of cases) and nonspecific abdominal pain (about 10%), meaning the cause often turns out to be something temporary or hard to pin down. But several serious conditions also live in the lower abdomen, and knowing the differences matters.
What the Location of Your Pain Can Tell You
Your lower abdomen spans from roughly your belly button down to your pelvis, and doctors divide it into three zones: lower right, lower left, and the center just above the pubic bone (the suprapubic area). Each zone holds different organs, so the location of your pain is one of the first clues to its cause.
Pain in the lower right is most associated with appendicitis, but it can also come from inflammatory bowel disease, an ovarian cyst, or a kidney stone on the right side. Lower left pain often points to diverticulitis, constipation, or similar conditions mirrored from the right side. Pain in the center, closer to the pubic bone, tends to involve the bladder (think urinary tract infections) or reproductive organs.
That said, pain doesn’t always stay in one spot. Appendicitis famously starts as a vague ache around the belly button before migrating to the lower right over 12 to 24 hours. That migration pattern is actually one of the most reliable signs of appendicitis, with about 80% accuracy for pointing toward the diagnosis. Only about half of people with appendicitis follow the “textbook” sequence of losing their appetite, feeling nausea, then developing right-sided pain and vomiting.
Common Digestive Causes
Most lower abdominal pain comes from the gut. Here are the conditions that show up most often:
Gas and constipation are the simplest explanations and by far the most common. Trapped gas creates sharp, crampy pains that shift around and eventually pass. Constipation builds pressure in the lower colon and can cause a dull, persistent ache, usually on the left side.
Gastroenteritis (a stomach bug) causes cramping throughout the abdomen, along with diarrhea, nausea, or vomiting. It’s the single most common diagnosis when people go to the ER for abdominal pain.
Irritable bowel syndrome (IBS) is a functional disorder, meaning the bowel’s structure looks normal but the nerves and muscles in it are overly sensitive. The hallmark is abdominal pain tied to changes in bowel habits: diarrhea, constipation, or both alternating. IBS pain tends to come and go over weeks or months, often triggered by certain foods or stress, and it typically eases after a bowel movement.
Diverticulitis feels different from IBS. It happens when small pouches that form in the colon wall become inflamed or infected, and it tends to cause steady pain on the lower left side, often with fever and nausea. Unlike IBS, diverticulitis involves actual structural inflammation, and it usually comes on over a day or two rather than waxing and waning for months. It’s more common after age 40.
Inflammatory bowel disease (Crohn’s disease or ulcerative colitis) causes chronic inflammation in the digestive tract. It can produce lower abdominal pain on either side, along with bloody stools, weight loss, and fatigue that persists for weeks.
Urinary Tract Causes
The bladder sits right behind the pubic bone, so infections there cause pain in the center of the lower abdomen. A urinary tract infection (UTI) typically produces a burning sensation when you urinate, a frequent urge to go, and a low, dull ache in the pelvic area. In women, UTI pain usually starts around the pubic bone.
Kidney stones feel completely different. The pain is sharp and stabbing, usually felt more in the back or side of your lower torso rather than the front of your abdomen. As a stone moves through the urinary tract, the pain can shift downward toward the groin. Both UTIs and kidney stones can cause blood in the urine, but the quality of the pain is a useful way to distinguish them.
Causes Specific to Women
The uterus, ovaries, and fallopian tubes all sit in the lower abdomen, which means women have a wider range of possible causes for pain in this area.
Menstrual cramps are the most common gynecologic cause. They produce a cramping or throbbing sensation in the central lower abdomen, usually starting just before or during a period.
Ovarian cysts are fluid-filled sacs on the ovary. Many come and go without symptoms, but larger ones can cause a dull ache on one side. If a cyst ruptures, it can leak fluid that irritates the surrounding tissue, causing sudden, sharp pain along with tenderness and bloating. A cyst can also twist (ovarian torsion), which causes severe, one-sided pain that comes on suddenly and often brings nausea with it. Torsion is a surgical emergency.
Endometriosis occurs when tissue similar to the uterine lining grows outside the uterus. It causes chronic pelvic pain that tends to worsen around periods, along with pain during sex and sometimes painful urination or bowel movements.
Pelvic inflammatory disease (PID) is an infection of the reproductive organs, usually caused by sexually transmitted bacteria. It produces lower abdominal tenderness, abnormal discharge, and sometimes fever above 101°F. PID can damage the fallopian tubes if left untreated, so early treatment matters.
Ectopic pregnancy is the most dangerous possibility. It occurs when a fertilized egg implants outside the uterus, usually in a fallopian tube. Early on, it causes localized pain on one side. If the tube ruptures, the pain becomes severe and spreads across the abdomen, sometimes with dizziness or shoulder pain from internal bleeding. Any woman of reproductive age with pelvic pain and a positive pregnancy test needs this ruled out immediately.
Causes Specific to Men
In men, the prostate gland and inguinal canal add a few unique possibilities. Prostatitis, or inflammation of the prostate, is one of the more common causes of persistent lower abdominal pain in men. The chronic form can cause pain or discomfort in the central lower abdomen, groin, or genital area lasting three months or longer. Acute bacterial prostatitis comes on faster, with pain accompanied by fever, chills, and difficulty urinating.
Inguinal hernias occur when tissue pushes through a weak spot in the lower abdominal wall, creating a bulge in the groin area. The pain is often a dull ache that worsens with coughing, bending, or lifting. Testicular torsion, where a testicle twists on its blood supply, causes sudden severe pain in the scrotum that can radiate up into the lower abdomen. It’s most common in teenagers and is a surgical emergency.
When Lower Abdominal Pain Is an Emergency
Most lower abdominal pain resolves on its own or with simple treatment. But certain patterns signal something that needs immediate medical evaluation:
- Sudden, severe pain that doesn’t ease within 30 minutes
- Pain with continuous vomiting, which can indicate a bowel obstruction or other serious condition
- Fever with worsening pain, suggesting infection or inflammation like appendicitis, diverticulitis, or PID
- A rigid abdomen that feels hard and is extremely tender to touch
- Signs of internal bleeding, including dizziness, fainting, or rapid heartbeat along with abdominal pain
- Inability to pass gas or have a bowel movement combined with bloating, which may indicate a bowel obstruction
How Doctors Figure Out the Cause
When you see a doctor for lower abdominal pain, they’ll ask about the location, timing, severity, and what makes it better or worse. They’ll also ask about your bowel habits, urinary symptoms, sexual history, and (for women) menstrual cycle and pregnancy status.
If imaging is needed, a CT scan is the first choice for pain focused in the lower right or lower left abdomen. For suspected appendicitis, CT detects it with about 91% sensitivity, compared to 78% for ultrasound. Some doctors use ultrasound first to avoid radiation exposure, reserving CT for cases where the ultrasound is inconclusive. This approach is especially common for younger patients and pregnant women. For pain centered over the bladder, a urine test is usually the starting point, since it can quickly identify an infection or blood that suggests a kidney stone.
For many people, the evaluation ends with reassurance. Roughly 1 in 10 ER visits for abdominal pain result in a diagnosis of “nonspecific abdominal pain,” meaning no dangerous cause is found. That’s not a dismissal. It means the serious possibilities have been ruled out, and the pain is likely from something self-limiting like a viral illness, muscle strain, or digestive irritation that will resolve in a few days.