Every month, it's the same scenario. Your period arrives, and your belly becomes a veritable field of batailleBetween the cramps and the frequent trips to the bathroom, you wonder if your body has decided to ruin your life. But you're not alone, you're not abnormal, and yes, there is a scientific explanation for all this. 73% of women have digestive problems during their periods, 28% of whom suffer from diarrhea. Yet, no one ever talks about it.
This article unpacks the link between your period and your bowel movements. You'll understand why your bowels go into overdrive exactly when you're bleeding, how to differentiate between "normal" period diarrhea and diarrhea that's a more serious problem like endometriosis, and, most importantly, how to manage these discomforts on a daily basis.
⚡ What to remember
You Are Not Alone: Reassuring Figures
Let's start by breaking the taboo. If you spend your first few hours of your period sitting on the toilet, you're part of a silent majority. A 2014 study shows stark numbers.
During or just before their period
During their period, when bleeding
Diarrhea in the days before menstruation
These figures show one simple thing: having disrupted bowel movements during your period is the norm, not the exception. Yet the subject remains taboo. We dare to say "I have my period" but rarely "my period gives me diarrhea." As a result, millions of women think they're the only ones who experience this, even though it's extremely common.
💡 Why this silence?
Talking about your period is already complicated in some circles. So talking about menstrual diarrhea seems downright indecent. Yet, it's a symptom as legitimate as cramps or fatigue. Your body isn't malfunctioning; it's just responding to a hormonal tsunami.
The Scientific Explanation: Prostaglandins Are Causing Trouble
If your bowel goes live exactly when you bleed, it's no coincidence. Your body produces hormones called prostaglandins to trigger uterine contractions and shed the endometrium (uterine lining). The problem is that these hormones don't have a very targeted action.
How it works
1️⃣ The endometrium detaches
When your period arrives, your uterus must shed the endometrium (the lining that has thickened to accommodate a potential embryo). To do this, your body produces prostaglandins.
2️⃣ Prostaglandins contract the uterus
These hormones cause uterine contractions to expel blood and tissue. This is what creates menstrual cramps (dysmenorrhea). The more prostaglandins there are, the stronger the contractions and the more painful they are.
3️⃣ They spread into the blood
Once produced by the endometrium, prostaglandins circulate in your blood. And then, disaster strikes: they don't stay quietly in the uterus. They reach neighboring organs, particularly the intestines.
4️⃣ The intestines also contract
Prostaglandins act on the smooth muscles of the intestinal wall just like they do on the uterus: they cause them to contract. As a result, your bowel movements suddenly speed up. Digested food passes through your intestines faster than usual, resulting in loose stools or even diarrhea.
Why Some Women Are More Affected
All women produce prostaglandins during their periods. But some produce more than others, or are more sensitive to them. Several factors come into play.
- Excessive production of prostaglandins : some women naturally produce more of it. It is often hereditary
- Diet rich in specific fatty acids : Prostaglandins are made from arachidonic and linoleic acid (found in red meats, vegetable oils, and nuts). Eating a lot of them can increase their production
- Intestinal sensitivity : women who already have irritable bowel syndrome (IBS) react more strongly to prostaglandins
- Stress and fatigue : they amplify the perception of digestive symptoms
Before vs. During Period: Two Different Mechanisms
Your transit can be disrupted at two distinct times in your cycle, but for different hormonal reasons. Understanding these mechanisms helps you anticipate and adapt your diet.
Phase 1: Before Period (Constipation)
In the days leading up to your period (luteal phase, after ovulation), it is the progesterone which dominates. This hormone has the opposite effect of prostaglandins: it slows everything down.
🐌 Slowing down of transit
Progesterone relaxes the smooth muscles in the intestinal wall. Digested food moves more slowly through your intestines, which can cause constipation.
💧 Water reabsorption
Stools remain in the colon for longer, where they reabsorb water. The result: harder stools that are more difficult to pass.
💨 Bloating and gas
Prolonged fermentation of food in the intestine creates gas. You end up with a bloated, tense, and uncomfortable stomach.
Phase 2: During Menstruation (Diarrhea)
As soon as your period starts, progesterone drops sharply and the prostaglandins take over. It's the opposite effect: everything suddenly accelerates.
🚀 Sudden acceleration
Prostaglandins stimulate intestinal contractions. Transit speeds up, and digested food passes through your intestines too quickly.
💧 No time to reabsorb water
Your intestines don't have time to recover the water contained in the stool. The result: loose stools or frank diarrhea.
🚽 Several trips to the bathroom
The first two days of your period, you may need to go to the bathroom 3, 4, or 5 times in the morning. This is normal (even if it's annoying).
💡 In the end
Your gut plays a yo-yo. Before your period, it's like a highway jam (constipation). As soon as it starts bleeding, all the lights turn green and it's off (diarrhea). Some women go straight from one to the other, which is particularly unsettling.
"Normal" Diarrhea vs. Endometriosis: The Differences You Need to Know
Having diarrhea during your period due to prostaglandins is common. However, if this diarrhea is accompanied by certain specific symptoms, it may signal a endometriosisThis disease affects 10% of women of childbearing age and is characterized by the presence of uterine tissue outside the uterus, particularly on the intestines.
Warning signs that should alert you
🚨 Disabling pain: If your menstrual cramps prevent you from functioning normally (work, social life), require strong painkillers or morphine, this is abnormal.
🩸 Blood in the stool during menstruation: Traces of red blood in your stool that appear right around the time of your period (catamenial rectal bleeding) may indicate digestive endometriosis.
💥 Pain during defecation: If having a bowel movement during your period causes deep, sharp, almost unbearable pain, seek medical help.
🎢 Severe alternating constipation/diarrhea: Abrupt shifts from one extreme to the other throughout the cycle, in a very unpredictable and disabling way.
🤰 Swollen belly like a "pregnant woman": Sudden, massive abdominal swelling that makes you look several months pregnant, with profound discomfort.
📅 Symptoms outside of periods: If these digestive problems persist outside of your period (with a peak during your period), this may indicate endometriosis.
⚠️ Action: If you check several of these boxes, consult a gynecologist. Ideally, seek out an endometriosis specialist. Diagnosis can take time (on average 7 years in France), but the sooner you act, the better.
The Case of Irritable Bowel Syndrome (IBS)
Women who already have irritable bowel syndrome (IBS) are particularly affected during their periods. A 2021 study shows that 50% of IBS patients experience abdominal bloating that impacts their daily lives during all the phases of the cycle, with a peak during menstruation.
If you have been diagnosed with IBS, you can expect your symptoms (diarrhea, constipation, pain, bloating) to significantly worsen during your period. This is related to your intestines' increased sensitivity to prostaglandins.
Concrete Solutions to Limit Menstrual Diarrhea
Now that we understand the mechanism, let's see how to manage it on a daily basis. There are several strategies to limit digestive discomfort during your period.
Strategy 1: Adapt Your Diet
What you eat in the days before and during your period can amplify or reduce symptoms.
✅ What helps
- Starchy and low-fiber foods : white rice, pasta, white bread, bananas (slow down transit)
- Avoid raw food 24-48 hours before your period : raw foods are more difficult to digest
- Broths and herbal teas : hydrate and soothe the digestive system
- Small, frequent meals : rather than 3 large meals, eat lighter but more often
❌ What makes everything worse
- Foods rich in arachidonic acid : red meat, cold cuts (increase the production of prostaglandins)
- Saturated fats and frying : slow down digestion and increase inflammation
- Dairy products : may worsen diarrhea in susceptible individuals
- Coffee and alcohol : stimulate transit and irritate the intestine
- Very spicy foods : accentuate intestinal irritation
Strategy 2: Anti-Inflammatories (Reduce Prostaglandins)
Nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen block the production of prostaglandins. By reducing prostaglandins, you reduce both menstrual cramps AND diarrhea.
💊 How to use them
- Start at the first signs : take an anti-inflammatory as soon as you feel your period coming (or at the first bleeding)
- Ibuprofen 400mg : every 6-8 hours for the first 2-3 days
- Take them with food : to protect your stomach
- Avoid if contraindicated : ulcer, kidney problems, severe asthma
Note: Paracetamol does not work for diarrhea because it does not block prostaglandins. It relieves pain but not digestive symptoms.
Strategy 3: Heat and Rest
Heat relaxes smooth muscles (uterus AND intestines) and can reduce excessive contractions.
- Hot water bottle on the stomach : 20-30 minutes several times a day
- Hot bath : relaxes the whole body and soothes cramps
- Repos : if possible, take it easy on the first day. Stress makes everything worse.
Strategy 4: Food Supplements
Certain natural active ingredients can help regulate transit and reduce inflammation.
🌿 Fennel
Antispasmodic properties that combat intestinal spasms. As a herbal tea or supplement.
💊 PEA (PalmitoylEthanolAmide)
Natural anti-inflammatory molecule produced by the body. Can reduce digestive symptoms related to menstruation.
🧘♀️ Magnesium
Relaxes muscles and can reduce the intensity of cramps (uterus and intestines).
Summary Table: Managing Your Transit During Your Cycle
To help you find your way around, here is a table that summarizes the phases of the cycle, what happens in your body and how to adapt your diet.
More Comfortable Periods
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Myths to Debunk About Digestion and Periods
There are many misconceptions about the link between menstruation and digestion. Let's set the record straight.
“It’s psychological, you stress so you have diarrhea.”
FALSE
Stress can aggravate digestive symptoms, it's true. But menstrual diarrhea has a clear and measurable biological cause: prostaglandins. It's not "in your head," it's in your hormones. Studies prove it: even perfectly zen women experience diarrhea during their periods if their prostaglandin levels are high.
“If you always have diarrhea, it’s because you’re eating badly.”
PARTIALLY TRUE
Diet plays a role, but it's not the main cause. You can have a perfect diet and still have diarrhea during your period due to prostaglandins. However, adjusting your diet can reduce the intensity of symptoms (avoiding foods that promote prostaglandin production, such as red meat).
“All women have diarrhea during their periods.”
PARTIALLY TRUE
73% of women experience digestive problems, 28% of whom experience diarrhea. So no, it's not "all of them," but it's a large majority. Some women have more moderate prostaglandin production or less sensitive intestines. Others have the opposite effect (constipation). Every body reacts differently.
“Having a bowel movement during your period increases your flow.”
FALSE
This belief stems from the fact that when you have a bowel movement, abdominal pressure can force blood out at the same time. But it doesn't create more blood, it just speeds up the evacuation. The uterus and rectum are close together, so it's mechanical. You don't "lose" more blood when you go to the bathroom.
Special Situations: Contraception, Menopause, Pregnancy
Certain situations change the impact of your period on your transit.
On the Contraceptive Pill
The pill blocks ovulation and stabilizes hormones. The result: fewer hormonal fluctuations, and therefore generally fewer digestive symptoms. Some women find that their menstrual diarrhea disappears or decreases significantly while on the pill. Others continue to experience it, but to a lesser extent.
At Menopause
When periods stop for good, cyclical digestive symptoms also disappear. Menstrual diarrhea is no longer present, since there are no more periods or cyclical prostaglandins. Some women find that their bowel movements finally stabilize at the menopause.
During Pregnancy
No period = no cyclical prostaglandins = no menstrual diarrhea. On the other hand, pregnancy brings its share of other digestive disorders (nausea, constipation due to high progesterone, reflux, etc.) but these are other mechanisms.
Your Menstrual Diarrhea Isn't Inevitable
Having diarrhea during your period is common and normal. Prostaglandins, which contract the uterus to shed the endometrium, also stimulate the intestines. The bottom line is: your bowel movements accelerate when you bleed.
However, you can mitigate the effects. Adjusting your diet, taking an anti-inflammatory at the start of your period, using heat, or resting can really help reduce discomfort.
If symptoms become debilitating (severe pain, blood in the stool, marked alternation of constipation and diarrhea), it's best to seek medical help. This could indicate digestive endometriosis or irritable bowel syndrome. An accurate diagnosis allows you to act sooner and better manage your cycle.
Sources & Scientific References
This article is based on published scientific studies and official medical recommendations.
Digestive disorders and menstrual cycle
- Bernstein MT, et al. (2014). Gastrointestinal symptoms before and during menses in healthy women. BMC Women's Health. DOI: 10.1186/1472-6874-14-14
- Heitkemper MM, et al. (2003). Impact of the menstrual cycle on gastrointestinal symptoms in women with irritable bowel syndrome. Digestive Diseases and Sciences. DOI: 10.1023/a:1023897317001
Prostaglandins and menstrual symptoms
- Marjoribanks J, et al. (2015). Nonsteroidal anti-inflammatory drugs for dysmenorrhoea. Cochrane Database of Systematic Reviews. DOI: 10.1002/14651858.CD001751.pub3
Irritable bowel syndrome and menstrual cycle
- Pati GK, et al. (2021). Irritable Bowel Syndrome and the Menstrual Cycle. Cureus. DOI: 10.7759/cureus.12692
- Moore J, et al. (1998). GI dysfunction in endometriosis: a pilot study. Acta Obstetricia et Gynecologica Scandinavica. DOI: 10.1034/j.1600-0412.1998.770613.x
Digestive endometriosis
- High Authority of Health (HAS). Endometriosis: symptoms and diagnosis. HAS Link
- EndoFrance Association. Digestive disorders and endometriosis. EndoFrance Link
Note: The information in this article is for informational purposes only and is not a substitute for medical advice. If symptoms are severe or persist, consult a healthcare professional.
Medical Warning: This article is for informational purposes only and is not a substitute for professional medical advice. If you experience severe pain, blood in your stool, or disabling symptoms, consult a gynecologist or gastroenterologist.
