Lower stomach pain in women has a long list of possible causes, ranging from period cramps to digestive issues to infections. What makes it tricky is that the uterus, ovaries, bladder, and intestines all sit close together in the lower abdomen, so pain from very different organs can feel similar. The location, timing, and accompanying symptoms are the best clues to narrowing it down.
Period Cramps and Prostaglandins
The most common reason for lower abdominal pain in women of reproductive age is menstrual cramping. During your period, the uterus contracts to shed its lining. Those contractions are driven by hormone-like chemicals called prostaglandins, which also trigger inflammation. Women who produce higher levels of prostaglandins tend to have more severe cramps. The pain typically starts just before or at the beginning of your period, centers below the belly button, and fades within two to three days.
If your cramps are manageable with over-the-counter pain relievers and a heating pad, they’re likely normal. But if they’re severe enough to keep you home from work or school, get worse over time, or don’t respond to typical remedies, something else may be going on.
Endometriosis
Endometriosis happens when cells similar to the uterine lining grow outside the uterus, on the ovaries, fallopian tubes, or other pelvic structures. These cells respond to your hormonal cycle the same way the uterine lining does: they thicken, break down, and bleed each month. But because the tissue has no way to exit the body, it causes inflammation, scarring, and pain.
The hallmark is pelvic pain that goes beyond typical cramps. It often includes pain during sex, pain with bowel movements or urination, and sometimes heavy periods. The pain can show up at any point in your cycle, not just during menstruation. Endometriosis is notoriously slow to diagnose, partly because many women assume their pain is just “bad periods.” If your lower abdominal pain consistently disrupts your life, especially if it comes with pain during intercourse or bathroom use, it’s worth raising with your provider.
Ovarian Cysts and Torsion
Your ovaries form small fluid-filled sacs (cysts) as a normal part of ovulation each month. Most dissolve on their own without you ever knowing they were there. Occasionally, though, a cyst grows large enough to cause a dull ache or pressure on one side of the lower abdomen. You might also feel bloating or fullness.
The more urgent scenario is ovarian torsion, where a cyst or enlarged ovary twists on its blood supply. This causes sudden, sharp, one-sided pain that can come with nausea and vomiting. Torsion is a medical emergency because the ovary can lose blood flow permanently if it isn’t corrected quickly.
Pelvic Inflammatory Disease
Pelvic inflammatory disease (PID) is an infection of the uterus, fallopian tubes, or ovaries, most often caused by sexually transmitted bacteria like chlamydia or gonorrhea. It can also involve bacteria that normally live in the vagina. The classic symptom is a persistent ache in the lower abdomen, often accompanied by unusual vaginal discharge, pain during sex, or irregular bleeding. Some women also develop a fever.
PID is diagnosed based on tenderness during a pelvic exam, combined with your symptoms and sometimes lab testing for STIs. It’s treated with antibiotics, and early treatment matters. Left untreated, PID can scar the fallopian tubes and lead to chronic pelvic pain, ectopic pregnancy, or fertility problems.
Urinary Tract Infections and Bladder Pain
A urinary tract infection (UTI) causes a burning sensation when you pee, frequent urges to urinate, and a pressure or ache just above the pubic bone. The pain is usually constant rather than crampy, and you may notice cloudy or strong-smelling urine. UTIs are caused by bacteria and clear up with a short course of antibiotics.
If those symptoms keep coming back but urine tests consistently show no bacteria, the problem may be interstitial cystitis (IC), a chronic bladder condition. IC produces many of the same symptoms as a UTI, including lower abdominal pressure and frequent urination, but also pain during sex. Because no infection is present, antibiotics don’t help. IC is typically diagnosed after other causes have been ruled out.
Irritable Bowel Syndrome
IBS is one of the most common digestive disorders, and women are disproportionately affected. The lower abdominal pain from IBS tends to come with bloating, gas, and changes in bowel habits (diarrhea, constipation, or both). What makes IBS distinctive is that the pain often improves after a bowel movement.
Women with IBS frequently notice their symptoms flare around the start of their period. Reproductive hormones appear to influence gut sensitivity, and research from UCLA suggests that women process visceral pain differently than men, with more activation in brain circuits tied to emotional arousal. This may partly explain why women are about four times as likely as men to seek gastroenterology care. If your lower stomach pain consistently tracks with digestive symptoms and seems to cycle with your period, IBS is a strong possibility to explore.
Appendicitis and Other Emergencies
Appendicitis is worth knowing about because it starts subtly and escalates fast. The pain often begins near the belly button, then migrates to the lower right side over several hours. It gets worse when you move, cough, or take deep breaths. Other signs include loss of appetite, nausea, vomiting, fever, and an inability to pass gas. If this pattern sounds familiar, get to an emergency room. A ruptured appendix is dangerous.
In women of childbearing age, ectopic pregnancy is another emergency to consider. This happens when a fertilized egg implants outside the uterus, usually in a fallopian tube. It causes sharp, one-sided lower abdominal pain and can lead to life-threatening internal bleeding if the tube ruptures. Any sudden lower abdominal pain paired with a missed period, vaginal bleeding, or dizziness warrants immediate medical attention.
How Location Helps Narrow It Down
Where exactly you feel the pain offers useful diagnostic clues:
- Right lower side: appendicitis, ovarian cyst or torsion on the right, ectopic pregnancy, kidney stone
- Left lower side: diverticulitis (more common over age 40), ovarian cyst or torsion on the left, constipation, kidney stone
- Center, below the belly button: menstrual cramps, UTI or bladder issues, PID, endometriosis, IBS
Pain that’s diffuse and hard to pinpoint is more common with IBS, PID, or endometriosis. Sharp, localized pain that came on suddenly points more toward a cyst, torsion, appendicitis, or kidney stone.
What to Expect at the Doctor’s Office
Your provider will start with your history: when the pain started, where it is, what makes it better or worse, and whether you have other symptoms like fever, discharge, or changes in urination or bowel habits. If you’re of reproductive age, a urine pregnancy test is standard to rule out pregnancy-related causes and to guide which imaging tests are safe.
A pelvic ultrasound is usually the first imaging step. It’s painless and gives a clear picture of the uterus and ovaries. A transvaginal ultrasound, where a small probe is inserted into the vagina, provides more detailed images and is commonly used to evaluate cysts, fibroids, or signs of ectopic pregnancy. If your provider suspects kidney stones, appendicitis, or diverticulitis, a CT scan of the abdomen and pelvis is typically the go-to because it’s fast and highly accurate. For chronic or hard-to-diagnose pelvic pain, an MRI may be used to look at soft tissues in more detail, including the pelvic floor muscles.
STI testing for chlamydia and gonorrhea is recommended when PID is a possibility. Urine cultures help distinguish a UTI from bladder conditions like interstitial cystitis. In some cases, particularly with suspected endometriosis, a definitive diagnosis requires a minor surgical procedure called laparoscopy, where a small camera is inserted through a tiny incision to directly visualize the pelvic organs.