Why Does Lower Back Pain Occur During Menstruation?

Lower back discomfort during menstruation is a common complaint among individuals who menstruate, often described as a dull, achy sensation rather than sharp pain. This symptom is primarily linked to the physiological processes underlying menstrual shedding of the endometrium.

The primary driver is uterine contraction—mediated by prostaglandins, lipid compounds released from the endometrium as it breaks down. These prostaglandins stimulate myometrial smooth muscle contractions to expel menstrual tissue. Because the uterus shares nerve pathways (via the T10–L1 and S2–S4 spinal segments) with the lower back and posterior pelvis, these contractions can refer pain or discomfort to the lumbar region—a phenomenon known as referred pain.

In addition to prostaglandin-mediated mechanisms, hormonal fluctuations—particularly the drop in estrogen and progesterone just before menses—may contribute to increased ligamentous laxity and altered pelvic biomechanics, potentially exacerbating mechanical strain on the lumbar spine and sacroiliac joints. In some cases, underlying conditions such as endometriosis, adenomyosis, or uterine fibroids may intensify prostaglandin production or cause structural distortion, leading to more pronounced or persistent low back symptoms.

While mild to moderate lumbar discomfort during menstruation is typically benign and self-limiting, worsening or non-cyclical back pain warrants clinical evaluation to rule out secondary gynecologic or musculoskeletal pathology.