Endometriosis by itself does not typically cause fever. The condition involves tissue similar to the uterine lining growing outside the uterus, and while it triggers inflammation, pain, and a range of other symptoms, a raised temperature is not a hallmark feature. However, certain complications of endometriosis, particularly infected cysts and ruptured growths, can absolutely cause fever, sometimes dangerously high.
If you have endometriosis and you’re running a fever, it’s worth understanding what might be going on, because the combination often points to something that needs prompt attention.
Why Endometriosis Alone Rarely Causes Fever
Endometriosis is a chronic inflammatory condition. Your immune system responds to the misplaced tissue, releasing inflammatory signals that cause pain, swelling, and fatigue. Some people with endometriosis report feeling generally unwell during flares, with low-grade temperature fluctuations, body aches, and exhaustion that can mimic the early stages of an infection. But this systemic inflammation doesn’t usually push your body temperature above the clinical fever threshold of 100.4°F (38°C).
When fever does appear alongside endometriosis symptoms, it’s a signal that something beyond the usual disease activity is happening.
Infected Endometriomas
Endometriomas are cysts that form on the ovaries in people with endometriosis. They’re filled with old blood and endometrial tissue, earning them the nickname “chocolate cysts.” These cysts can become infected, and when they do, fever is one of the primary symptoms.
About 2.3% of people with endometriomas develop a tubo-ovarian abscess, a pocket of infected fluid involving the ovary and fallopian tube. That percentage sounds small, but the consequences are serious. An infected endometrioma can produce fevers as high as 104°F (40°C) along with intense pelvic pain, abdominal tenderness, and signs of widespread infection. In one documented case, a 32-year-old woman with a history of endometriosis surgery arrived at the emergency department with a fever of 104°F and abdominal rigidity consistent with peritonitis, an infection of the abdominal lining. Severe endometriosis is considered a specific risk factor for this kind of complication.
Ruptured Endometriomas
An endometrioma can also rupture, spilling its contents into the pelvic and abdominal cavity. When that material is already infected, or when the rupture itself triggers inflammation severe enough to irritate the peritoneum (the membrane lining the abdomen), fever follows. The typical presentation includes sudden, severe abdominal pain, nausea, vomiting, and fever. Abdominal muscles may become rigid and tender to the touch.
This situation can escalate. A ruptured infected endometrioma can cause acute diffuse peritonitis, which in turn can progress to sepsis and septic shock. In a case reported in Acta Medica Lituanica, a 49-year-old woman came to the emergency room with three days of fever and severe lower abdominal pain. Imaging and surgery confirmed a ruptured infected endometrioma that had caused widespread peritonitis. These cases require surgical treatment, often urgently.
Fever After Endometriosis Surgery
If you’ve recently had laparoscopic surgery for endometriosis, a mild temperature elevation in the first 24 to 48 hours is common and usually not concerning. Your body mounts an inflammatory response to the surgery itself, and a slight rise in temperature is part of that normal healing process.
Postoperative fever becomes clinically significant when your temperature exceeds 100.4°F (38°C) on two consecutive days after surgery, or reaches 102.2°F (39°C) or higher on any single day. At that point, potential causes include surgical site infection, urinary tract infection from catheterization, or less commonly, a deeper pelvic infection. Very high fevers above 104°F (40°C) occurring within 30 to 40 minutes of a procedure can indicate bacteremia, where bacteria have entered the bloodstream.
Most post-surgical fevers in the first day or two resolve on their own. Fevers that start or persist beyond the first 48 hours, especially with increasing pain, redness at incision sites, or foul-smelling discharge, point to infection and need evaluation.
Other Reasons for Fever With Pelvic Pain
It’s also possible that fever and pelvic pain are coming from a condition that coexists with, or is mistaken for, endometriosis. Pelvic inflammatory disease (PID), caused by bacterial infection of the reproductive organs, produces pelvic pain, fever, and abnormal discharge. Ovarian torsion, where an ovary twists on its blood supply, can cause severe pain and sometimes fever. Urinary tract infections and kidney infections also cause pelvic or lower abdominal pain with fever.
Because endometriosis symptoms overlap with so many other conditions, a new fever alongside your usual symptoms is worth investigating rather than assuming it’s just a bad flare.
When Fever With Endometriosis Needs Urgent Care
Any fever of 100.4°F (38°C) or higher combined with pelvic or abdominal pain warrants medical attention, especially if you have known endometriomas. Seek care sooner rather than later if you also experience repeated vomiting, signs of dehydration like dark urine or dry mouth, abdominal rigidity or pain that worsens with movement, confusion, or difficulty breathing. These combinations can indicate peritonitis or early sepsis, both of which require rapid treatment.
A low-grade temperature during a painful endometriosis flare, while uncomfortable, is less likely to signal an emergency. But fever that climbs, persists beyond a day or two, or arrives with symptoms you don’t normally experience during flares is your body flagging something different from the usual pattern.