Lower abdominal pain has dozens of possible causes, ranging from mild and temporary (trapped gas, muscle strain, menstrual cramps) to serious and time-sensitive (appendicitis, ectopic pregnancy, a strangulated hernia). Where exactly the pain sits, how it started, and what other symptoms come with it are the most useful clues for narrowing down what’s going on.
The lower abdomen houses parts of the large and small intestine, the bladder, the appendix, and, in women, the uterus and ovaries. Pain in this area can originate from any of these structures, or it can be referred pain traveling from somewhere else entirely, like a kidney stone higher up in your urinary tract.
Where the Pain Is Matters
Your lower abdomen is broadly divided into three zones: the right side, the left side, and the center (just above the pubic bone). Each zone has a somewhat different shortlist of likely causes, though there’s overlap.
- Right lower side: Appendicitis is the classic concern here, but this area also covers part of the colon, the right ovary and fallopian tube, and the right ureter. Inflammatory bowel disease, ovarian cysts, and kidney stones can all produce pain on this side.
- Left lower side: Diverticulitis is the standout cause on this side because the sigmoid colon, where small pouches most commonly form in people of European descent, sits in the lower left. Constipation, inflammatory bowel disease, and left-sided ovarian problems also show up here.
- Center (suprapubic): Bladder infections, menstrual cramps, and pelvic inflammatory disease tend to produce pain in the middle, low down. Constipation and early appendicitis can also cause vague central discomfort before the pain migrates to one side.
Appendicitis
Appendicitis is one of the most common surgical emergencies, and its hallmark is pain that starts vaguely around the belly button, then moves to the lower right side over the course of several hours. That migration pattern is distinctive. Along with the shifting pain, you may notice a loss of appetite, nausea or vomiting, and a low-grade fever.
The pain typically gets worse with movement, coughing, or even riding over bumps in a car. If someone presses firmly on your lower right abdomen and then quickly releases, a sharp spike of pain on release (called rebound tenderness) is a strong indicator of inflammation in that area. Pain in the right side that appears when someone presses on your left side is another classic sign. These aren’t things to test on yourself at home, but they explain what a doctor is checking for during an exam.
Appendicitis can progress to a ruptured appendix within 24 to 72 hours of symptom onset. If you have worsening right-sided pain with fever and vomiting, treat it as urgent.
Digestive Causes
Irritable bowel syndrome (IBS) is one of the most common reasons for recurring lower abdominal pain, especially when the pain comes with bloating and changes in bowel habits like alternating constipation and diarrhea. The pain often improves after a bowel movement. IBS is diagnosed when this pattern persists for at least several months without another explanation. It’s not dangerous, but it can significantly affect quality of life.
Diverticulitis produces a different kind of pain: steady, often severe, and concentrated on the lower left side. It develops when small pouches in the colon wall become inflamed or infected. Fever, nausea, and a noticeable tenderness when you press on the area are typical. About 4% of people who have these pouches (a common finding on colonoscopy, especially after age 40) will eventually develop an episode of diverticulitis. Most cases resolve with rest and antibiotics, but complicated cases can require hospitalization.
Constipation is easy to overlook as a cause of real pain, but stool backed up in the lower colon can produce cramping, bloating, and diffuse lower abdominal discomfort that sometimes feels alarming. If your pain coincides with not having had a bowel movement in a few days, that’s worth noting before assuming something more serious.
Inflammatory bowel disease, which includes Crohn’s disease and ulcerative colitis, causes pain along with bloody stools, urgency, weight loss, and fatigue. The pain tends to be chronic and episodic rather than sudden and new.
Urinary Tract and Kidney Stones
A urinary tract infection (UTI) affecting the bladder produces a burning sensation when you urinate, a frequent urgent need to go, and a dull ache or pressure in the lower center of your abdomen. The pain is usually mild to moderate, and there may be cloudy or strong-smelling urine. UTIs are far more common in women than men.
Kidney stones produce a very different experience. When a stone moves into the narrow tube connecting your kidney to your bladder, the pain is intense, sharp, and comes in waves. It typically starts in your side or back below the ribs and radiates down into the lower abdomen and groin. Many people describe it as the worst pain they’ve ever felt. You may also notice blood in your urine, nausea, and a restless inability to find a comfortable position. The pain shifts as the stone moves, which can make it feel like the problem is in your lower abdomen when the stone reaches the lower part of the ureter.
Gynecological Causes
In women and people with female reproductive organs, the lower abdomen is home to structures that generate their own set of pain patterns distinct from digestive or urinary causes.
Ovarian cysts are fluid-filled sacs that form on the ovaries, often during ovulation. Most are small, cause no symptoms, and resolve on their own. Larger cysts or ones that rupture can cause sudden, sharp pain on one side of the lower abdomen. Ovarian torsion, where the ovary twists on its blood supply, produces severe one-sided pain with nausea and is a surgical emergency.
Endometriosis causes tissue similar to the uterine lining to grow outside the uterus, most often on the ovaries, fallopian tubes, and pelvic lining. The result is chronic lower abdominal and pelvic pain that tends to worsen around your period but can occur at any time. Pain during sex and painful bowel movements during menstruation are common. Because the symptoms overlap with IBS and other conditions, endometriosis takes an average of several years to diagnose.
Ectopic pregnancy occurs when a fertilized egg implants outside the uterus, usually in a fallopian tube. Early warning signs include light vaginal bleeding and pelvic pain on one side. If the tube ruptures, the pain becomes severe and can be accompanied by shoulder pain (from blood irritating the diaphragm) or an unusual urge to have a bowel movement. This is a life-threatening emergency. Any lower abdominal pain with vaginal bleeding in someone who could be pregnant warrants immediate evaluation.
Pelvic inflammatory disease (PID), an infection of the reproductive organs usually caused by sexually transmitted bacteria, produces dull, constant lower abdominal pain on both sides along with unusual discharge, pain during sex, and sometimes fever.
Hernias and Muscle Strain
An inguinal hernia occurs when tissue pushes through a weak spot in the lower abdominal wall, creating a visible or palpable bulge near the groin. The pain is often a dull ache that worsens with lifting, bending, or coughing. Many hernias can be gently pushed back in and cause only intermittent discomfort.
The situation becomes dangerous when a hernia gets trapped (incarcerated) and can no longer be pushed back in. If the blood supply to the trapped tissue gets cut off, the hernia is strangulated. Symptoms escalate quickly: sudden worsening pain, nausea, vomiting, fever, and a bulge that turns red or purple. A strangulated hernia requires emergency surgery.
Muscle strain is a simpler explanation that people often forget. The abdominal muscles can be pulled or torn from heavy lifting, intense exercise, or even prolonged coughing. This pain worsens with movement and is tender to the touch at a specific spot, but it doesn’t come with fever, changes in bowel habits, or urinary symptoms. It generally improves with rest over a week or two.
Signs That Need Immediate Attention
Most lower abdominal pain resolves on its own or turns out to be something manageable. But certain combinations of symptoms signal a problem that can’t wait. The American College of Emergency Physicians recommends seeking emergency care if your pain is sudden, severe, or doesn’t ease within 30 minutes. Continuous severe pain accompanied by persistent vomiting is another red flag that suggests a serious or life-threatening condition.
Other warning signs to take seriously: a rigid or board-like abdomen, fever above 101°F alongside abdominal pain, bloody stool or vomit, fainting or lightheadedness, pain during pregnancy, or an inability to pass gas or have a bowel movement. These can point to conditions like a ruptured appendix, ectopic pregnancy, bowel obstruction, or internal bleeding, all of which worsen rapidly without treatment.
How Doctors Figure Out the Cause
When you show up with lower abdominal pain, the evaluation typically starts with questions about when the pain began, whether it’s constant or comes in waves, what makes it better or worse, and what other symptoms you have. A physical exam focuses on pressing different areas of your abdomen to locate tenderness and checking for signs of inflammation.
For right lower quadrant pain, a CT scan with contrast is the standard first imaging study. It’s highly accurate for identifying appendicitis, diverticulitis, kidney stones, and ovarian problems. Ultrasound is the preferred starting point for pregnant women and is also useful for evaluating ovarian cysts and ectopic pregnancy. For pregnant women with suspected appendicitis, MRI without contrast is an equivalent alternative to ultrasound, avoiding radiation exposure while still providing detailed images.
Blood work and a urine test round out the initial workup. Elevated white blood cells point toward infection or inflammation. A pregnancy test is standard for women of reproductive age with lower abdominal pain, because ectopic pregnancy must be ruled out early. A urinalysis can quickly identify a UTI or blood in the urine suggesting a kidney stone.