Rare & Unexpected Endometriosis Symptoms You May Not Have Heard Of


When people talk about endometriosis, the focus is usually on painful periods, infertility, and pelvic pain. But did you know that endometriosis can show up in some unexpected and even downright strange ways?

For some, endo doesn’t just stay in the pelvic region—it can affect the lungs, digestive system, and even the belly button. And while it’s rare, it has even been found in men.

If you’ve ever had symptoms that don’t fit the "typical" endometriosis picture, you’re not alone. Here are some of the lesser-known—but very real—ways endo can show up.

Abstract image of uterus and lungs with lines connecting them to each other to represent endometriosis symptoms and their potential connection to each other.

1. Endometriosis in the Lungs (Catamenial Pneumothorax)

Yes, endometriosis can affect your lungs. A rare condition called catamenial pneumothorax happens when endometrial-like tissue grows on the diaphragm (the muscle that helps you breathe) or even inside the lungs themselves.

Since this tissue still responds to hormonal changes, it can lead to lung collapse during menstruation. Symptoms include:

✔ Chest pain that worsens around your period
✔ Shortness of breath during menstruation
✔ Shoulder pain (referred pain from the diaphragm)

Because this condition is underdiagnosed, many women go years without realizing their breathing issues might be cycle-related. If you have recurring chest pain or unexplained breathing trouble that flares around your period, it’s worth discussing with a doctor.


2. Bleeding Through the Belly Button

Another surprising symptom? Some women bleed from their belly button during their period.

This is caused by umbilical endometriosis, where endometrial tissue implants itself in or around the navel. Along with bleeding, women with this condition often experience:

✔ A dark or bloody discharge from the belly button
✔ Swelling or tenderness around the navel
✔ A small lump that gets worse around menstruation

Although it’s rare, this symptom is a sign of deep infiltrating endometriosis and should be checked out by a specialist.


3. The Digestive Connection: Endometriosis & IBS

Many women with endometriosis are misdiagnosed with Irritable Bowel Syndrome (IBS) before they ever receive the correct diagnosis. That’s because endo can affect the bowels, causing symptoms that mimic IBS, including:

Bloating (“endo belly”)
Alternating constipation & diarrhea
Severe cramping with bowel movements
Pain that flares around menstruation

For some, endometrial lesions form directly on the bowel, leading to pain and digestive issues that get worse around their cycle.

If you’ve been diagnosed with IBS but your symptoms seem tied to your period—or if your treatments aren’t working—it may be worth looking into bowel endometriosis.


4. Endometriosis in Men: Yes, It Happens

Although endometriosis is overwhelmingly a condition found in women, rare cases have been documented in men.These cases are usually linked to:

Hormone therapy (such as estrogen treatment for prostate cancer)
Developmental factors during fetal growth
Genetic mutations affecting hormone regulation

Men with endometriosis have had endometrial-like tissue found in the bladder, pelvic region, and even the lungs. While incredibly rare, this suggests that endometriosis is more than just a reproductive disease—it’s a complex condition involving immune and hormonal dysfunction.


The Takeaway: Endometriosis is More Than Just Period Pain

Endometriosis is a whole-body condition, and its symptoms can range far beyond the reproductive system. If you’ve been experiencing symptoms that don’t seem to fit the “typical” endo profile, trust your body and keep pushing for answers.

If you suspect you may have endo but haven’t been diagnosed, your current treatment isn’t working, or your pain is being dismissed, find a specialist who truly understands this condition. Navigating an endometriosis diagnosis often requires a team approach—combining medical treatment with holistic support can help you feel more in control, more supported, and more like yourself for the long term.