What Constipation Followed By Sudden Diarrhea Can Mean

Key takeaways:

• Diarrhea occurs when the movement of the intestinal muscles causes an abnormally rapid transit of food through the intestine.
• Explosive diarrhea sometimes follows constipation and might be a sign of an underlying condition.
• Modifying your diet or routine often helps with constipation and diarrhea.

Diarrhea is the passage of three or more loose stools in one day. Explosive diarrhea occurs when fluid and gas build up in the rectum, causing a sense of urgency followed by the expulsion of loose stools and gas. Usually, fluids exit the gut in the large intestine. But when diarrhea occurs, there’s not enough time for this process to happen since the movement of the gut rapidly propels contents of the intestine through to the rectum.

On the flip side, constipation may be caused by dehydration, lack of exercise, and low dietary fiber content. It makes stools hard and difficult to pass. Constipation that’s followed by diarrhea may be a sign of a gastrointestinal condition, infection, food intolerance, or another chronic issue. We’ll explore some of the potential causes below.

Causes of constipation followed by sudden or explosive diarrhea

Constipation can occur as a result of dehydration, side effects of medication, a low-fiber diet, and lack of exercise. It can also happen with stress or anxiety. Causes of diarrhea include increased intestinal muscle contractions, changes in the bacteria in the gut, gastrointestinal infection, and food intolerance or allergy.

Some conditions may result in constipation followed by explosive sudden diarrhea. Here’s a look at situations that can cause both symptoms.

Irritable bowel syndrome

Irritable bowel syndrome (IBS) refers to a group of gastrointestinal disorders. It is associated with abdominal pain and abnormal defecation. Diagnosis is based on having recurrent abdominal pain with at least two of the following symptoms at least once a week for at least three months:

• Abdominal pain related to defecation
• A change in stool frequency
• A change in stool consistency

Patients often report an increased passage of gas or a bloated feeling. Some people feel a sense of urgency when they need to defecate. They may not feel as if they have emptied their bowels after using the bathroom.

There are four subtypes of IBS; constipation followed by diarrhea may occur in mixed IBS.

• IBS with predominant diarrhea (IBS-D): Loose, watery stools
• IBS with predominant constipation (IBS-C): Stools are frequently small and hard
• IBS with mixed bowel habits: A quarter of all bowel movements are diarrhea, and a quarter are constipation
• IBS unclassified: People who meet the diagnostic criteria of IBS but cannot be accurately classified.

Inflammatory bowel disease

Inflammatory bowel disease (IBD) is a group of chronic diseases caused by the body’s autoimmune reaction to its own intestinal tissues. This reaction causes intestinal inflammation. Inflammation can cause tissue damage and ulcerations in the intestines.

IBD can also alter the permeability of the intestine, allowing toxins and bacteria into the bloodstream. These chemicals heighten the body’s inflammatory response. The two primary bowel disorders are ulcerative colitis and Crohn’s disease.

The symptoms of Crohn’s disease and ulcerative colitis can include both constipation and diarrhea, although diarrhea is more common. Other symptoms of IBD are blood in the stool, fatigue, nausea, vomiting, and weight loss. The anus and rectum may also become irritated and itchy.

Bacterial overgrowth

The gut microbiome refers to the microorganisms in a healthy intestine. These include bacteria, viruses, and fungi that aid digestion. They may also boost your physical and mental health. In IBS, the balance of good bacteria that help digestion may be altered.

Good bacteria also keep harmful bacteria from taking over the gut. You may have more harmful bacteria than a person with a healthy digestive tract. Small intestinal bacterial overgrowth may occur. Chemicals produced by harmful bacteria may interact with the nervous system in the gut and cause diarrhea or constipation.

Diet

Suddenly adding a lot of fiber to relieve constipation and other dietary changes can cause explosive diarrhea after constipation.

Also, eating foods that irritate the digestive tract while you are constipated may cause explosive diarrhea. These include:

• Spicy foods
• Cruciferous vegetables (broccoli, cabbage, and Brussels sprouts)
• Legumes (beans, peas, lentils)
• Dairy products
• Foods that contain gluten (pasta, flour, and some grains)
• Food with seeds

Gastrointestinal infection

Intestinal infections can cause pathogens like bacteria, viruses, or parasites to trigger an immune response. Infections often cause inflammation in the digestive tract, which may disrupt normal muscle contractions in the intestines. This condition is known as peristalsis.

As a result of abnormal muscle contractions in the intestines, the movement of digestive contents becomes irregular. When digestion is slowed, constipation occurs. Conversely, diarrhea happens when digestion is sped up.

As the infection progresses, the diarrhea can cause dehydration, and the body tries to conserve water. Dehydration can lead to harder stools and constipation. When this built-up waste finally moves through the system, it often results in explosive diarrhea.

Food allergies or intolerance

Food intolerances trigger a complex chain of events in the digestive system. Eating foods to which you are intolerant or allergic triggers an inflammatory response in the gut. This inflammation affects the gut's nerve network. It disrupts normal intestinal muscle contractions.

Food intolerances can draw excess water into the intestines. They can also cause gas and bloating, which slows transit time. People often eat less when they have active infections. When their appetite returns, they sometimes resume eating at a rapid pace, which might cause diarrhea.

Constipation with overflow diarrhea

Constipation results in hard stools that are sometimes difficult to pass. If stool becomes impacted (stuck in the intestine), watery, liquid stool can leak around the blockage. Impaction usually occurs in people who are chronically constipated and in older adults.

Laxatives

Using a lot of laxatives when constipated can also cause explosive diarrhea following constipation.

How to tell if your symptoms are related to IBS

IBS-related diarrhea and constipation have a unique pattern. This pattern sets the conditions apart from other digestive disorders. The main signs are:

• Symptoms that last at least three months
• Abdominal pain or discomfort that usually improves after bowel movements.
• Pain is linked to changes in stool frequency and consistency
• Symptoms often worsen during stress or anxiety
• Symptoms are generally more severe in the morning
• Symptoms usually occur in waking hours
• Mucus is often present in diarrhea
• Blood and stool samples are normal

The absence of other signs distinguishes IBS from more severe conditions. With IBS, there's typically none of the following manifestations:

• Unexplained weight loss
• Blood in the stool
• Fever
• Constant abdominal pain
• Abnormal blood tests and stool samples

How to get quick relief from constipation followed by sudden diarrhea

If you have constipation followed by sudden diarrhea, you might need to treat each symptom separately for immediate relief. Here are a few essential tips that can help you lessen the severity and frequency of your symptoms quickly:

• Stay hydrated by sipping on plenty of water and clear fluids.
• Engage in gentle physical activity to combat constipation.
• Place a warm heating pad on your belly to soothe cramps and discomfort.
• If you’re constipated, consider using an osmotic laxative like milk of magnesia, glycerin, or polyethylene glycol (Miralax) instead of stimulant laxatives.
• Try sitting in a position such as squatting when using the toilet.
• Gently massage your abdomen in a clockwise direction to encourage stool to move through your digestive tract.

Long-term treatment and prevention options for constipation followed by sudden diarrhea

Managing the cycle of constipation followed by diarrhea requires a comprehensive approach. Both the symptoms and their underlying causes need to be addressed. Here are some long-term treatment and prevention strategies:

Adjust dietary fiber

If you need more fiber in your diet, start increasing your fiber intake to 25–35 grams daily through whole grains, fruits, and vegetables. Start slowly to avoid worsening symptoms, and drink plenty of water. Proper fiber intake can help regulate bowel movements and prevent constipation and explosive diarrhea.

Exercise regularly

Establish a consistent exercise routine of at least 30 minutes daily. Try activities like walking, swimming, or yoga. Physical activity stimulates natural intestinal contractions and helps maintain regular bowel habits.

Manage stress levels

Try some stress-reduction methods like meditation, deep breathing, or yoga. Chronic stress can significantly affect intestinal muscle movement and inflammation. Managing these stress levels usually helps normalize bowel patterns and prevent symptom flare-ups.

Regular meal times

Establish regular meal times, and never skip meals. Eating at consistent times helps regulate bowel movements by training your digestive system to function on a schedule. Eating breakfast within an hour of waking up is important.

Probiotic supplements

Probiotics are live microorganisms that usually inhabit a healthy gut. A high-quality probiotic supplement daily can help you maintain a healthy gut bacteria balance.

Choose products containing multiple strains and at least 10 billion colony-forming units (CFUs). Probiotics help prevent both constipation and diarrhea by supporting proper digestion and gut function.

When to see a doctor for constipation followed by sudden diarrhea

If you are experiencing constipation followed by sudden diarrhea, it’s essential to know when you should seek medical care.

You should see a doctor if:

• Your diarrhea and constipation symptoms last more than a week.
• You experience unintentional or unexplained weight loss.
• Your symptoms don’t respond to over-the-counter remedies or home treatments.
• You experience frequent abdominal pain or symptoms that interfere with daily activities.
• You have a family history of colon cancer or IBD.

You should go to the emergency room if:

• You experience severe, persistent abdominal or rectal pain.
• You notice significant amounts of blood in your stool or notice dark red, black, or tarry stools.
• You have a fever higher than 102°F.
• You show signs of severe dehydration, such as extreme thirst, dry mouth, dizziness, dark urine, decreased urination.
• You experience other symptoms, such as repeated vomiting, rapid heart rate, weakness, confusion, lightheadedness, or fainting.

Questions to ask your doctor about constipation and sudden diarrhea

• What conditions are related to constipation and sudden or explosive diarrhea?
• What tests will I need to rule out serious causes of constipation and sudden or explosive diarrhea?
• What lifestyle changes may help with my symptoms?
• When should I seek emergency care for these symptoms?

Frequently asked questions: constipation and sudden diarrhea

Constipation and sudden explosive diarrhea can occur for several reasons. Treatment should be tailored to your symptoms and underlying conditions. Below are some frequently asked questions about constipation and sudden diarrhea.

What if you’re pregnant and experience constipation and sudden diarrhea?

Constipation and diarrhea that occur during pregnancy can harm both the pregnant person and fetus. That said, diarrhea and constipation are common in pregnancy. Hormonal changes, especially increased progesterone, are known to slow digestion. Also, the growing uterus puts pressure on the intestines.

Is constipation followed by sudden diarrhea a sign of cancer?

Constipation and diarrhea can sometimes be a sign of colorectal cancer. These are more commonly caused by less serious conditions like IBS, food intolerances, or infections. Cancer is more likely when specific warning signs accompany your symptoms:

• Unexplained weight loss
• Blood in or on your stool (either bright red or very dark)
• Persistent abdominal pain that doesn't improve after bowel movements
• A sensation that your bowel isn't emptying completely
• Persistent narrow, pencil-thin stools that persist
• Extreme fatigue
• Anemia (low iron levels)
• Symptoms that get progressively worse over time
• New symptoms that occur when you are over 50 years old
• Family history of colorectal cancer

If you're experiencing any of these symptoms, you should see a medical professional for an evaluation. They may recommend screening tests like colonoscopies, particularly if you're over 45 or have risk factors. Early detection and treatment of colorectal cancer can significantly improve outcomes, so don't hesitate to discuss any concerning changes in bowel habits with your doctor.

Final thoughts

Normally, the large intestine absorbs fluids when digesting food. During diarrhea, intestinal muscle contractions increase and speed food passage through the intestine, preventing the reabsorption of fluids. This leads to watery stools.

Constipation, often from dehydration, inactivity, or low fiber, causes hard stools. Your body may respond with rapid intestinal movement. This pushes fluid, gas, and stool to the rectum.

The combination of backed-up waste and rapid transit can result in explosive diarrhea due to pressure buildup in the rectum. Both symptoms and their underlying causes should be addressed.

General Medicine follows a strict editorial process, including using real experts to write our articles, vetted primary sources, fact-checking, a secondary medical review, and updates as necessary. This article was medically reviewed and fact checked by Dr. Lane Thaut, DO.

Sources

American Society of Health-System Pharmacists, Inc. "Treatment for Diarrhea." National Institute of Diabetes and Digestive and Kidney Diseases, NIH, 1 Nov. 2016.

Body, Cameron, and Jennifer A Christie. “Gastrointestinal Diseases in Pregnancy: Nausea, Vomiting, Hyperemesis Gravidarum, Gastroesophageal Reflux Disease, Constipation, and Diarrhea.” Gastroenterology Clinics of North America vol. 45,2 (2016): 267-83. doi:10.1016/j.gtc.2016.02.005

Louwagie, Victoria, et al. “Fecal impaction in adults.” JAAPA: Official Journal of the American Academy of Physician Assistants vol. 36,5 (2023): 19-22. doi:10.1097/01.JAA.0000923532.69484.95

Fritz, Cassandra D L, et al. “Red-flag signs and symptoms for earlier diagnosis of early-onset colorectal cancer.” Journal of the National Cancer Institute vol. 115,8 (2023): 909-916. doi:10.1093/jnci/djad068