A female GI doctor who specializes in women’s GI issues addresses IBS vs. menstrual cramps related to PMS.

What are the differences between IBS cramps and those from premenstrual syndrome?

“The main difference between menstrual cramps and IBS cramps would be the timing,” begins Diana Y. Wu, MD, a gastroenterologist and assistant professor of medicine at Brown Medical School.

“Menstrual cramps usually occur a few days before onset of menstruation, whereas IBS cramps can occur at any time, especially in the mornings, after eating, or in times of stress/anxiety.

“IBS cramps can often be relieved by having a bowel movement. Menstrual cramps tend to be lower in the pelvis and not necessarily relieved with defecation. It tends to resolve after the menstrual cycle is completed.”

The cause of the cramps in irritable bowel syndrome and in PMS differs.

In PMS the cause is hormones called prostaglandins, which is why the anti-prostaglandin drug, ibuprofen, is so effective at relief.

The prostaglandins cause uterine contractions, and that’s the “cramping” that a woman feels.

“Irritable bowel syndrome is characterized by chronic abdominal pain, and associated with changes in stool frequency or consistency (e.g., diarrhea or constipation) in the absence of any physical cause that is detectable by our current medical investigations,” explains Dr. Wu.

“The pain is usually relieved or ameliorated with a bowel movement.”


“The pathophysiology of IBS remains unclear and is believed to be multifactorial,” continues Dr. Wu.

“Despite multiple investigations, data have been conflicting and no abnormality has been found to be specific for this disorder.”

I’ve never had IBS so I can’t describe what the cramping feels like. But I’ve had cramping from premenstrual syndrome and microscopic colitis, and they feel identical.

Ironically (though not surprisingly), prostaglandins are implicated in flare-ups of microscopic colitis, though research in this area is scant.

I know that the cramping I had, during the microscopic colitis flare, was related to this benign inflammatory bowel disease because when it happened, I had already completed menopause. Very fascinating!

But prostaglandins don’t seem to be involved in the cramping of IBS.

Causes of IBS are not clear.

“The traditionally favored hypotheses are: alterations in gastrointestinal motility (no predominant pattern of motor activity has emerged as a marker for IBS), visceral hypersensitivity, alteration in fecal flora (such as after gastrointestinal infection/food poisoning), bacterial overgrowth, food sensitivity or a genetic predisposition,” explains Dr. Wu.


Bacterial overgrowth and food sensitivities are theorized to be causative factors behind microscopic colitis, which is often misdiagnosed as IBS…and vice versa.

Dr. Wu further explains, “Visceral hypersensitivity (increased sensation in response to stimuli) is a frequent finding in irritable bowel syndrome patients.

“Several studies have focused on increased sensitivity of visceral nerves in the gut, triggered by bowel distention or bloating, as a possible explanation for IBS symptoms.

“About half of patients with IBS experience bloating in addition to abdominal pain.

“They may have a measurable increase in abdominal girth associated with bloating (sensation of abdominal fullness), and this may be due to impaired transit of intestinal gas loads.”

Is there a way a woman can tell if the cramps she feels are IBS related or from PMS or mid-cycle cramping?

“There is no way to know for sure. However, typically IBS cramping is relieved with defecation.”

Dr. Wu is a graduate of Harvard Medical School and is board certified in gastroenterology and internal medicine. She is well-versed in multiple endoscopic procedures and all GI disorders.
Lorra Garrick has been covering medical, fitness and cybersecurity topics for many years, having written thousands of articles for print magazines and websites, including as a ghostwriter. She’s also a former ACE-certified personal trainer.  


Top image: ©Lorra Garrick

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