Endometriosis can produce symptoms ranging from mild or intermittent discomfort to severe, persistent pain and substantial effects on everyday life, and some people have no obvious symptoms at all. The characteristic pattern is often pain associated with menstruation, particularly period pain that is much more severe than expected or interferes with normal activities.
Other common symptoms include pelvic or lower abdominal pain, lower-back pain, pain during or after sex, pain when passing urine or opening the bowels, heavy periods, fatigue and difficulty becoming pregnant. Symptoms depend strongly on where endometriosis is located, how surrounding tissues react and whether adhesions, ovarian endometriomas or deep infiltrating lesions have developed. Consequently, symptom severity does not necessarily indicate how extensive the visible disease is.
Severe menstrual pain is one of the most recognisable symptoms. Ordinary period cramps are largely produced by uterine contractions and prostaglandin activity, whereas endometriosis can cause additional inflammation, tissue irritation, fibrosis and nerve sensitisation. Pain may begin before menstruation, become worse during bleeding and persist afterwards, although individual patterns vary. Pain that repeatedly prevents normal work, education, exercise, sleep or social activities is particularly important clinically. Heavy menstrual bleeding can also occur, although not everyone with endometriosis has heavy periods. The presence of severe period pain does not prove endometriosis because adenomyosis, fibroids and other disorders can produce similar symptoms, but unusually severe or progressively worsening menstrual pain warrants medical assessment.
Pelvic pain can occur outside menstruation and may become chronic. It may be felt deep in the lower abdomen, pelvis, lower back or around the hips, and can fluctuate with hormonal changes or occur continuously. Inflammation around pelvic structures, adhesions that restrict normal organ movement and irritation of nerves can all contribute to pain. The location of pain can therefore provide clues but cannot reliably identify the exact location of disease.
Some people experience pain around ovulation, while others have symptoms throughout the cycle. Importantly, the intensity of pain does not necessarily correlate with the number or size of lesions; a small lesion affecting a sensitive area can be extremely painful, while extensive disease can sometimes cause little discomfort.
Endometriosis can affect the bowel and urinary tract, producing symptoms that may initially appear gastrointestinal or urinary rather than gynaecological. Bowel-related symptoms can include pain when opening the bowels, bloating, altered bowel habits and, in some cases, rectal bleeding that follows a menstrual pattern. Bladder or urinary involvement can cause pain when urinating, urinary frequency or blood in the urine, particularly around menstruation.
These symptoms can resemble irritable bowel syndrome, urinary tract disorders or other pelvic conditions, which is one reason diagnosis can take time. The NHS also notes that, rarely, endometriosis can occur outside the pelvis, including in the chest, where cyclical chest pain, shortness of breath or coughing blood can occur and requires medical assessment.
Pain during or after sexual intercourse, medically termed dyspareunia, is another important symptom. Deep pelvic lesions, inflammation, scarring and adhesions can make movement of pelvic organs painful during penetration. The symptom may be especially associated with disease affecting tissues behind the uterus, the vaginal-rectal region or other deep pelvic structures. Pain during sex is not specific to endometriosis and can arise from vaginal dryness, pelvic-floor dysfunction, infection, hormonal changes or other disorders, so it should not automatically be attributed to one cause. Nevertheless, recurrent deep pain associated with intercourse, especially alongside severe periods or pelvic pain, is clinically relevant and should be discussed with a healthcare professional.
Fatigue is frequently reported and can be substantial. It may arise from chronic inflammatory activity, persistent pain, disrupted sleep, psychological stress, heavy menstrual bleeding and iron deficiency or anaemia in people who have significant blood loss. Fatigue can therefore be both a direct consequence of living with a chronic inflammatory condition and an indirect consequence of its effects on sleep and daily functioning. Some people also experience low mood, anxiety or reduced quality of life. These psychological effects do not mean that endometriosis pain is psychological; rather, chronic pain and unpredictable symptoms can affect mental wellbeing, relationships, employment and participation in ordinary activities.
Fertility difficulties can occur because endometriosis may distort pelvic anatomy, create adhesions, affect ovarian function or interfere with the normal relationship between the ovaries, fallopian tubes and surrounding tissues. Endometriosis does not mean that pregnancy is impossible, and many people with the condition conceive naturally or with appropriate fertility support. Conversely, infertility can sometimes be the first reason endometriosis is discovered, particularly when pain is limited or absent. Fertility problems therefore belong to the clinical spectrum but are not required for diagnosis. A person should not assume that an absence of fertility problems excludes endometriosis, nor that infertility automatically means endometriosis is responsible.
Symptoms can overlap substantially with other conditions, which is a major reason endometriosis can be difficult to recognise. Adenomyosis can cause painful and heavy periods, fibroids can cause bleeding and pelvic pressure, pelvic inflammatory disease can cause pelvic pain, and irritable bowel syndrome can produce abdominal pain and bowel symptoms. Some people have endometriosis discovered incidentally during surgery despite having few symptoms. Conversely, severe symptoms can occur without extensive disease visible on initial investigations.
A persistent pattern of severe period pain, pelvic pain, pain during sex, bowel or urinary pain, unexplained fatigue or fertility difficulty merits discussion with a clinician rather than self-diagnosis. Ultrasound and MRI can provide useful information, while laparoscopy can directly inspect the pelvis and may confirm disease in appropriate circumstances.
