About 20% of women experience cramping or pain around the middle of their menstrual cycle, right when an egg is released from the ovary. The medical term is mittelschmerz, German for “middle pain,” and it happens because ovulation is a surprisingly physical event. Your ovary doesn’t just quietly release an egg. It swells, stretches, ruptures, bleeds a little, and triggers a localized inflammatory response that your body can absolutely feel.
What Actually Happens Inside Your Ovary
Each month, a single egg matures inside a fluid-filled sac called a follicle. As the follicle grows, it stretches the surface of the ovary. That stretching alone can produce a dull ache or pressure. Then, when the follicle finally ruptures to release the egg, it breaks through the outer wall of the ovary entirely. Both the stretching beforehand and the rupture itself can cause pain.
When the follicle breaks open, it releases fluid and a small amount of blood into the pelvic cavity. This fluid can irritate the lining of the abdomen (the peritoneum), which is rich in nerve endings. Even a small amount of fluid in the wrong spot is enough to trigger that sharp, crampy sensation you feel low in your pelvis.
Ovulation Triggers an Inflammatory Response
What makes ovulation pain more intense for some women is that the process closely resembles inflammation from an injury. When the brain signals the ovary to release the egg (via a hormone surge), blood vessels in the follicle dilate, fluid accumulates, and immune cells flood into the tissue in a pattern nearly identical to what happens after a physical wound. The ovarian wall weakens and eventually gives way.
Your body also ramps up production of prostaglandins, the same chemical messengers responsible for period cramps. Prostaglandins cause smooth muscle to contract in the fallopian tubes and around the ovary. These contractions help draw the egg into the tube, but they also contribute to the cramping you feel. One type of prostaglandin in particular stimulates the longitudinal muscles of the fallopian tube in a dose-dependent way, meaning the more your body produces, the stronger the contractions.
What Ovulation Pain Feels Like
The hallmark of ovulation cramping is that it’s one-sided. Because only one ovary releases an egg each cycle, the pain shows up on one side of your lower abdomen. It may switch sides from month to month, or you might notice it more often on the same side if one ovary tends to be more active.
The sensation varies. Some women describe a sharp twinge that lasts a few minutes. Others feel a dull, nagging ache that persists for hours. The pain typically lasts anywhere from a few minutes to 24 to 48 hours. You might also notice light spotting or a change in vaginal discharge around the same time. The timing is predictable: roughly 14 days before your next period, give or take a day or two depending on your cycle length.
When the Pain Points to Something Else
Mild to moderate cramping that lines up with mid-cycle timing and resolves within a couple of days is almost always normal ovulation pain. But severe pain that leaves you doubled over, lasts longer than 48 hours, or gets worse over time is worth investigating. Several conditions can amplify or mimic ovulation pain.
Endometriosis is one of the most common culprits behind unusually intense mid-cycle cramping. When endometrial tissue grows outside the uterus, it responds to the same hormonal shifts that drive ovulation, producing inflammation and pain that goes well beyond typical mittelschmerz. Other signs of endometriosis include severe period cramps, pain during sex, chronic pelvic pain, and difficulty getting pregnant.
Ovarian cysts can also complicate the picture. A follicular cyst forms when the follicle doesn’t rupture and instead keeps growing. These are usually painless, but if one does rupture, it can cause a sudden, sharp pain on one side. A corpus luteum cyst, which forms after the egg is released, can occasionally bleed internally and cause pain as well. If you have polycystic ovary syndrome (PCOS), the many small cysts on the ovary surface generally don’t cause pain on their own, but the hormonal imbalances involved can affect how ovulation feels overall.
How Ovulation Pain Is Diagnosed
There’s no blood test or imaging scan that confirms mittelschmerz. Diagnosis is based on timing and your description of the pain. A healthcare provider will ask about your cycle, when in the month the pain occurs, how long it lasts, and whether it’s always on the same side. They may do a pelvic exam to rule out other causes like cysts, infection, or endometriosis. If your symptoms are straightforward and line up with the middle of your cycle, that’s usually enough to confirm the diagnosis.
Relieving Ovulation Cramps
Because prostaglandins play a central role in the cramping, over-the-counter anti-inflammatory painkillers like ibuprofen or naproxen are the most effective option. These work by blocking prostaglandin production, which reduces both the inflammation at the ovary and the muscle contractions in the fallopian tubes. Taking one at the first sign of mid-cycle pain, rather than waiting for it to build, tends to work best.
A heating pad on your lower abdomen can also help relax the smooth muscle contractions. A warm bath works similarly. For women who experience ovulation pain every month and find it disruptive, hormonal birth control is an option because it prevents ovulation from happening in the first place. No ovulation means no follicle stretching, no rupture, and no mid-cycle inflammatory response.
Ovulation Pain and Fertility Tracking
If you’re trying to conceive, ovulation pain is one of the most straightforward signs that your body is releasing an egg. The pain can occur just before or during the moment of rupture, so it’s a real-time signal of your most fertile window. Combined with other signs like changes in cervical mucus or a slight rise in basal body temperature, mid-cycle cramping can help you pinpoint timing without relying on test strips alone. That said, not every woman feels it every cycle, so it works best as one piece of the puzzle rather than your only tracking method.