Diarrhea

Loose stools and urgent, frequent bowel movements—especially when they worsen during menstruation—are a pattern many people report with endometriosis. Some describe it as “period diarrhea,” while others notice alternating diarrhea and constipation, cramping, or rectal pressure. When endometriosis involves the bowel or the tissues around it, digestive symptoms can become one of the most disruptive parts of a cycle.

With endometriosis, inflammation and endometrial-like tissue outside the uterus can irritate the bowel itself (most often the rectum/sigmoid colon) or the pelvic nerves that regulate gut motility. During your period, natural prostaglandins (hormone-like inflammatory chemicals) rise—this can increase intestinal contractions and fluid secretion, making stools looser. If endometriosis is present, that normal cycle-related effect can become amplified and more painful.

Adenomyosis—where endometrial tissue grows into the uterine muscle—does not directly grow on the bowel, but it can still contribute to bowel symptoms. People with adenomyosis often have very painful, heavy periods and an inflamed, tender uterus. That pelvic inflammation, cramping, and “crowding” sensation can trigger bowel urgency, worsen diarrhea during menses, or increase sensitivity to normal gut movements—especially in those who also have endometriosis (a common overlap).

It’s important to know that diarrhea around menstruation can also happen in people without endometriosis (a normal prostaglandin effect), and it can overlap with irritable bowel syndrome (IBS), infections, food intolerances, celiac disease, or inflammatory bowel disease (IBD). What raises concern for endometriosis is a cyclical pattern plus pelvic pain, deep pain with bowel movements, pain with sex, infertility, or symptoms that persist/worsen over time. Our Evaluation & Diagnosis process focuses on sorting out these overlaps so you’re not left guessing.

When diarrhea is tied to your cycle, it can affect work, school, travel, intimacy, sleep, and nutrition—especially if you’re also dealing with nausea, bloating, or pain medications that disturb the gut. You deserve to have this taken seriously and evaluated as part of the whole endometriosis/adenomyosis picture, not brushed off as “just IBS.”

Patients often describe diarrhea with endometriosis/adenomyosis as sudden urgency, repeated trips to the bathroom, or loose stools that come in waves with cramping. It may feel like the bowel is “spasming,” with pain that can be low in the pelvis, deep in the rectum, or radiating into the lower back. Some people notice a sharp, stabbing pain just before or during a bowel movement, followed by temporary relief and then another wave.

A common pattern is cyclical flares: bowel symptoms intensify in the days leading up to bleeding and peak during the first 1–3 days of the period. Others have ongoing baseline digestive sensitivity with predictable period worsening. You may also notice mucus in stool, a sense of incomplete emptying, or pelvic pressure—especially if symptoms occur alongside painful bowel movements or bloating.

Experiences vary widely. Some people only have mild loose stools during menses; others have severe diarrhea that leads to dehydration, dizziness, or fear of leaving home. If adenomyosis is present, the bowel symptoms may track with heavy bleeding and intense uterine cramping—while bowel endometriosis more often includes pain with bowel movements, cyclical rectal pain, or sometimes bowel-related bleeding (which always deserves prompt evaluation).

GI symptoms are very common in endometriosis, and diarrhea is one of the most frequently reported—particularly around menstruation. Studies consistently show that people with endometriosis report significantly higher rates of bowel symptoms (including diarrhea, constipation, bloating, and abdominal pain) than those without endometriosis, and many also meet criteria for IBS-like symptoms.

Not everyone with diarrhea has bowel endometriosis. Diarrhea can occur due to inflammatory signaling in the pelvis even when lesions are not on the bowel wall. However, a cyclical pattern (repeating around the same cycle days) increases suspicion that endometriosis and hormone-driven inflammation are contributing.

Symptom severity does not always match “stage” of endometriosis. Even superficial disease can cause major bowel symptoms if it irritates sensitive areas or nerves, while some people with deep disease have fewer GI symptoms. Location matters: endometriosis involving the posterior pelvis (behind the uterus), rectovaginal space, or bowel is more likely to correlate with bowel urgency, painful bowel movements, and cyclical diarrhea. For deeper discussion, see our GI Symptoms and Bowel Endometriosis resources.

In endometriosis, endometrial-like lesions can implant on or near the bowel and pelvic lining. These lesions can bleed microscopically and trigger an inflammatory response, releasing cytokines and prostaglandins that affect intestinal movement and sensitivity. The result can be faster transit time (diarrhea), cramping, and urgency—especially during menstruation when inflammatory signaling naturally increases.

If endometriosis is deep and affects tissues around the rectum/sigmoid colon, it may also cause mechanical and functional changes: tethering (scar-like adhesions), reduced bowel flexibility, and pain-driven pelvic floor tightening. Interestingly, pelvic floor guarding can contribute to both constipation and diarrhea/urgency because the system becomes dysregulated. That overlap is one reason symptoms can alternate.

With adenomyosis, the uterus itself becomes inflamed and can be enlarged or tender. Severe uterine cramping during periods can increase pelvic prostaglandins and irritate nearby bowel loops, leading to loose stools or urgency. Many patients with adenomyosis also have endometriosis, so bowel symptoms may reflect a combined disease process.

Other factors can worsen cycle-related diarrhea: NSAIDs (which can irritate the stomach and intestines), magnesium-containing supplements, high-FODMAP foods during a flare, stress and poor sleep (which alter gut motility), and coexisting IBS/IBD. A careful history and coordinated evaluation help separate these contributors so treatment can be targeted. See Related Conditions and our IBS / IBD category for more nuance.

Treatment depends on why diarrhea is happening—hormone-driven motility changes, bowel endometriosis, pelvic floor dysfunction, overlapping IBS/IBD, medication side effects, or a combination. The most helpful first step is a thorough workup through an endometriosis-focused lens, such as our Evaluation & Diagnosis, so your plan addresses root causes rather than just suppressing symptoms.

Medical options may include hormonal suppression to reduce cycle-related inflammation and prostaglandin surges, which can lessen period diarrhea for some patients. Learn more in our Hormonal Therapy resource. Symptom-targeted medications (like antidiarrheals used thoughtfully, antispasmodics, or bile acid binders when indicated) may be appropriate—especially for predictable period flares—while also considering side effects and safety.

Surgical treatment can be important when diarrhea is driven by bowel involvement, deep infiltrating disease, or adhesions. Excision surgery (removing disease at its root) is widely regarded as the gold standard approach for endometriosis, particularly when lesions affect complex areas like the bowel. Our team specializes in advanced, minimally invasive approaches described in Surgery & Advanced Excision with care led by Dr. Steven Vasilev. When bowel endometriosis is suspected, multidisciplinary planning is key for both safety and outcomes.

Lifestyle and self-care strategies can reduce day-to-day suffering and support the gut during flares—especially while you pursue definitive treatment. Many patients benefit from:

• Keeping a symptom-and-cycle log (timing, foods, stress, meds)
• Hydration and electrolyte support during heavy diarrhea days
• Short-term dietary adjustments during flares (often lower-fat, lower-FODMAP, or bland foods—individualized)
• Reviewing supplements (e.g., magnesium) and NSAID use with your clinician

Our Integrative Medicine & Lifestyle Care approach often includes nutrition, stress regulation, and evidence-informed adjuncts when appropriate.

Pelvic floor physical therapy may help if urgency/diarrhea alternates with constipation, pain with bowel movements, or rectal/pelvic pressure—signs that muscle guarding and nerve sensitization may be part of the picture. It can also help after surgery or during medical therapy by reducing protective tension that amplifies bowel symptoms. For broader pain strategies, explore Pain Management.

If you want a plan that looks at endometriosis, adenomyosis, and gut symptoms together—and prioritizes lasting relief—learn about our services.

Seek urgent medical care if you have any of the following: blood in the stool, black/tarry stools, fever, severe dehydration (fainting, inability to keep fluids down), persistent vomiting, severe worsening abdominal pain, or signs of bowel obstruction (no gas/stool passing, marked bloating with escalating pain). Even if you have known endometriosis, these symptoms deserve prompt evaluation.

Schedule a specialist visit if diarrhea is cyclical (worse during menstruation), interferes with daily life, occurs with pelvic pain, painful bowel movements, heavy bleeding, or infertility, or if you’ve been told it’s “just IBS” but your symptoms keep returning. Endometriosis commonly takes years to diagnose—early, expert evaluation can shorten that timeline and help prevent ongoing inflammation and pain sensitization. Our Evaluation & Diagnosis process is designed to connect the dots.

When you meet with a clinician, bring details: timing in your cycle, frequency/urgency, stool changes, foods/meds that trigger it, associated symptoms (bloating, nausea, rectal pain, pain during sex), and any family history of IBD/celiac. If you’re ready for a comprehensive plan, you can schedule a consultation or contact us to be seen by the Lotus Endometriosis Institute team.