Watery Diarrhea Before Period: Am I Pregnant? (5 Reasons To Worry)

Question: Is watery diarrhea before period a sign of pregnancy or period coming?

When you are expecting your period, there are many changes you will expect in your mood, breasts, abdomen and also your vaginal discharge.

These changes are common in a lot of girls and its nothing abnormal if you get these symptoms a week before period. These premenstrual symptoms are sometimes called PMS (premenstrual syndrome). 

You will notice your breast feels sore and painful. Also, your vaginal discharge becomes thick and dry before the start of your next period. Most notably is cramping pain in your abdomen that starts few days before period.

If you are expecting these symptoms, and then, notice constipation or watery stool before period, its normal you will be worried why it’s happening.

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Here’s an email from Aziza (one of my readers)

Hi Dr. Dunn

Im a 24 years old student and need a little advice to know what’s wrong with me. I have 30 days menstrual cycle, and I’m supposed to have my period on the 15th of July. However, I’m having watery diarrhea, and I’m worried because I experienced the same symptoms during my last menstruation.

Two days before my last period started, I noticed watery frequent stooling that continued during my period. Is this normal or I have been infected by a virus?

Just like Aziza, its natural you will get concerned if you experience cyclical diarrhea before your period. The truth is, it can be normal for some women and often occurs because of hormone changes that occur around your menstrual period. However, if it is very severe, lasts more than a few days, or comes with blood or high fever, you should not ignore it.

Having said that, diarrhea before period may be due to bacterial, viral or parasitic infections of your intestines. Common causes of prolonged diarrhea are food poisoning, infections, irritable bowel syndrome, ulcerative colitis, and sometimes due to medications you are taking. 

This article explains causes of watery diarrhea before period, symptoms that indicate it could be pregnancy, and when your diarrhea is due to a serious health concern.

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Is it normal to have diarrhea before period starts?

In a woman’s body, there are plenty of hormones that work every time to ensure that your menstrual cycle functions normally.

At the end of your cycle, levels of estrogen and progesterone fall. This drop is what triggers the shedding of your uterine lining and the start of your period.

Estrogen is the most dominant hormone before ovulation, and then after ovulation your body’s estrogen level fall a little with a subsequent rise in another hormone, progesterone.

This hormone, progesterone, has many effects on a woman’s body, and apart from preparing your womb for pregnancy (should you get pregnant after sex), there are other functions

1. Endometrium thickening

After ovulation, there are changes to the thickness of your endometrium. The endometrium is a blood thickened layer that carpets the inside of your uterus. This thickness of the endometrium makes it possible for implantation to occur in women that get pregnant.

2. Reduce the possibility of miscarriage

One common reason women get an early miscarriage is a problem with implantation or early development of the pregnancy. Progesterone helps maintain the uterine lining and support early pregnancy. However, most early miscarriages are due to chromosomal problems in the baby and are not caused by anything the woman did or did not do.

3. Reduce contraction of the Intestinal smooth muscles

In your abdomen are small and large intestines. Their function is to move useless waste matter from your body and push them out through your anus. Smooth muscles cover the small and large intestine and can be affected by progesterone hormone.

Initially, after ovulation, there is a rise in progesterone hormone, and this reduces the contraction of smooth muscles resulting in decreased motility, and therefore constipation (hard stool).

Because progesterone levels fall 3 – 4 days before period, and also during menstruation, many women will notice more frequent stooling or softer stool right before period starts.

Another reason you could have diarrhea before period is prostaglandins.

Prostaglandins have a hormone-like effect on your uterus around menstruation and cause contraction of uterine muscles to expel endometrial blood from your womb.

In some women that experience severe cramping, your body produces an excessive level of prostaglandins, which moves to other parts of your body, including your intestine, resulting in diarrhea.

Prostaglandins cause contraction of the smooth muscles of the intestinal wall with resultant frequent stool and diarrhea. They are also a major cause of period cramps. You can read more about how prostaglandins cause menstrual pain here:
Period pain (dysmenorrhea) – MedlinePlus

So, if your loose stool always comes one or two days before your period and settles after menstruation, hormones are a likely reason.

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Can Diarrhea before period be a sign of pregnancy?

If you are very concerned about your health and feel you are pregnant, there are other ways to know if you are pregnant before missed period.

The most reliable way is a pregnancy test (urine or blood), especially from the day your period is late or 10–14 days after unprotected sex.

Some women notice a very light bleeding or spotting (sometimes called implantation bleeding) about the time their period is due, but many women never have this at all. Because of this, implantation bleeding is not a reliable way to confirm pregnancy by itself. You can read more here:
Implantation bleeding – Cleveland Clinic

Other more typical signs of early pregnancy are a delayed period, increased clear watery discharge, fatigue, breast pain, frequent urination, mood changes and nausea. See common early pregnancy symptoms here:
Am I Pregnant? Early Symptoms of Pregnancy – Cleveland Clinic

Apart from these signs, constipation and diarrhea can happen in pregnancy for some women, but they are not specific signs.

During early pregnancy, your body produces different hormones that affect your digestive system resulting in vomiting, diarrhea, constipation, and nausea. Diarrhea alone, especially if it is short-lived and just before your period, is usually more related to your cycle than pregnancy.

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Diarrhea before period: When to Worry?

Apart from hormonal changes that are beyond your control, you could have diarrhea for a different reason. Sometimes, it could be due to what you’ve eaten, other times it could be due to a serious health problem.

In fact, you should see your doctor immediately if you are experiencing any of these symptoms:

• Acute pain in your abdomen

• Severe back pain that worsens over days

• Blood in diarrhea or black, tarry stool

• High body temperature (fever)

• Feeling weak and tired due to effects of dehydration (dry mouth, very little urine, dizziness)

• Rectal or anal pain with bleeding

• Nausea and vomiting, especially if you cannot keep fluids down

• Diarrhea lasting more than 2–3 days without improvement

If you have any of these signs, don’t wait, talk to a doctor about your symptoms quickly. You can also check this general guide on when to see a doctor for diarrhea:
Diarrhea – When to see a doctor – Mayo Clinic

Here are some reasons you have diarrhea before your period that won’t go away:

1. Endometriosis

Endometriosis is the displacement of parts of your endometrium to other location in your body. It can be found in your abdomen, ovaries or on the outer surface of your womb.

If this happens, some women feel diarrhea or pain when passing stool around period time, though most common symptoms are a painful period, painful sexual intercourse, and heavy bleeding during menstruation.

2. Food poisoning

Sometimes, your diarrhea may be due to what you’ve taken for breakfast, lunch or dinner. If you’ve just taken a meal that contains bacteria, toxin or virus, your body will react, resulting in vomiting, nausea, abdominal pain, loose stool, and fever.

3. Crohn disease / Ulcerative colitis

If your intestine gets inflamed, it could cause you to have persistent stooling for weeks. Ulcerative colitis is the inflammation of the large intestine and can also affect your rectum.

Symptoms are diarrhea, abdominal pain, weight loss, bloody stool, and fever.

Irritable bowel syndrome (IBS) can also flare around your period and cause loose stool or cramping in some women.

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How to stop diarrhea before period?

If you are experiencing so much passage of watery stool days before period, here’s how to feel better:

• Have a lot of bedrest

• Take small frequent sips of water or oral rehydration solution to prevent dehydration

• Stop smoking and alcohol if you do

• Eat simple, bland foods (like rice, bananas, toast) and avoid very greasy or spicy foods

• An over-the-counter anti-diarrheal like loperamide (Imodium) may help if you do not have fever, blood in your stool or severe pain. Always follow the instructions on the pack or your doctor’s advice, and avoid these medicines in pregnancy unless your doctor approves.

• See a doctor for severe symptoms, diarrhea that lasts more than a few days, or if you are pregnant and worried about your baby

For more details on general treatment and tests for diarrhea, you can also read:
Diarrhea – Diagnosis and treatment – Mayo Clinic