Why period cramps hurt so much — the science behind the pain

6 min read  ·  Science-backed

Every month, the same thing. That familiar tightening in your lower abdomen, the dull ache radiating into your back, the kind of pain that makes you cancel plans and reach for a heating pad. Period cramps are one of the most common experiences women have — and yet they are still massively underestimated. If you've ever been told to "just push through it," this article is for you. Because what's happening inside your body during a cramp is far more complex — and far more legitimate — than most people realize.

It starts with prostaglandins

The main culprit behind period cramps is a group of chemical compounds called prostaglandins. Despite the name, they are not hormones — they are lipid compounds produced locally in the uterine lining (endometrium) that act like chemical messengers, triggering inflammation and muscle contractions.¹

Here's what happens: just before your period begins, progesterone and estrogen levels drop sharply. This hormonal drop triggers the breakdown of the endometrial tissue. As the tissue breaks down, it releases phospholipids which are converted into arachidonic acid, and from there into prostaglandins — specifically PGF2α and PGE2, the two types most responsible for cramping.²

What a contraction actually feels like — from the inside

When prostaglandins trigger a uterine contraction, your uterus squeezes — hard. These contractions serve a purpose: they help expel the uterine lining. But during an intense contraction, the uterus can temporarily cut off its own blood supply.³ This creates a state of ischemia — a lack of oxygen in the uterine tissue — which is the same mechanism that causes the pain of a heart attack in cardiac muscle.

The two types of prostaglandins each play a different role:

Together, they create a cycle of contraction, oxygen deprivation, inflammation, and amplified pain. Research published in PMC (NIH) confirms that elevated prostaglandin levels are the primary driver of primary dysmenorrhea — the medical term for painful period cramps with no underlying condition.⁴

Why some women feel it more than others

Not everyone experiences cramps the same way, and that's not a matter of pain tolerance — it's biology. Women who produce higher levels of prostaglandins experience stronger, more frequent uterine contractions and more intense pain.⁵ Research also shows that the nervous system plays a role: central sensitization — where the brain becomes more sensitive to pain signals over time — can make cramps feel even worse for some women, particularly those who experience severe pain regularly.⁶

Stress is another significant factor. When you're under stress, your body produces more cortisol, which can increase inflammation and raise prostaglandin production — which directly intensifies cramping.⁷ This is why a particularly stressful month often comes with a particularly painful period. It's not a coincidence.

The back pain, the nausea, the headaches — why?

Period pain rarely stays in one place. The lower back ache, nausea, diarrhea, and headaches that often accompany cramps are all connected to prostaglandins too. Because these compounds travel through the bloodstream, they can affect muscles and organs beyond the uterus — triggering contractions in the bowel (causing diarrhea or nausea) and affecting blood vessels throughout the body (contributing to headaches).⁸

This is also why cramps can feel like a full-body experience rather than just localized abdominal pain. Your uterus is not suffering in isolation — your entire body is responding to the chemical signals it's sending.

Why some months are so much worse

If you've noticed that your cramps vary significantly from one month to the next, you're not imagining it. Hormonal levels are never perfectly consistent — sleep quality, nutrition, stress levels, and even the season can shift estrogen and progesterone enough to change how much prostaglandin your body produces that cycle.⁹ A month of poor sleep and high stress can genuinely result in a more painful period the following week. Your cycle is a living system, and it responds to everything happening in your life.

What actually helps — and why

Anti-inflammatory pain relievers (NSAIDs) like ibuprofen work by blocking the enzymes (COX enzymes) that produce prostaglandins. Taken before cramps peak, they can significantly reduce pain — not because they mask it, but because they reduce the root cause.⁴

Heat relaxes uterine muscle contractions and increases blood flow to the area, directly counteracting the ischemia that causes pain. Studies show heat applied to the abdomen can be as effective as ibuprofen for mild to moderate cramps.¹⁰

Movement increases endorphin production — your body's natural painkiller — and helps reduce overall inflammation. Even a short walk during your period can measurably reduce cramping intensity.

Tracking your cramps. When you log your pain day by day, you start to see patterns — which days hurt most, whether stress or sleep made things worse, whether certain months are consistently harder. That information is powerful, both for managing your own cycle and for having informed conversations with your doctor.

Understanding your cramps starts with knowing your cycle. Open Feelings to see your phase — and log your symptoms and flow so you can track how your pain pattern shifts across cycles.