What causes period cramps?

Bottom linePeriod cramps are caused by the uterus contracting to shed its lining, driven by prostaglandins, with higher levels causing stronger pain; ordinary (primary) cramps have no underlying disease, while worsening or severe (secondary) cramps can signal endometriosis, adenomyosis, or fibroids. See a doctor if pain doesn't ease with NSAIDs, worsens over time, disrupts life, or occurs with sex or heavy bleeding.

Period cramps (dysmenorrhea) are caused by your uterus contracting to shed its lining. The contractions are driven by hormone-like chemicals called prostaglandins - higher levels mean stronger cramps.

Two types

• Primary dysmenorrhea: ordinary period cramps with no underlying disease. Common, often eases with age and after childbirth.
• Secondary dysmenorrhea: cramps caused by a condition like endometriosis, adenomyosis, fibroids, or PID. These tend to be more severe or worsen over time.

Typical pattern

• Cramping in the lower abdomen, sometimes the back and thighs
• Starts just before or as your period begins
• Worst in the first 1 to 2 days
• May come with bloating, loose stools, headache, or fatigue

When to see a doctor

• Pain that doesn't ease with NSAIDs (ibuprofen, naproxen)
• Pain that gets worse over time or is severe enough to disrupt life
• Pain during sex or bowel movements
• Cramps with heavy bleeding or that start later in life

Worsening or NSAID-resistant pain can point to endometriosis.

See how to relieve period cramps and period pain vs endometriosis pain.

Track cramp severity with your cycle in Femora to spot whether pain is steady or worsening.