Constipation happens when stool moves too slowly through the intestines or becomes too dry and hard, making it difficult to pass.

What Causes Constipation?

1. Everyday lifestyle and diet factors

These are the most common, often fixable causes.

  • Not enough fiber (few fruits, vegetables, whole grains).
  • Not drinking enough fluids or being mildly dehydrated.
  • Eating lots of highly processed foods and refined carbs (white bread, white rice, fast food).
  • Low physical activity, sitting or lying down most of the day.
  • Regularly ignoring the urge to have a bowel movement (too busy, no access to toilet).
  • Sudden changes in routine (travel, new job, different sleep schedule).
  • High intake of dairy (for some people).

These factors slow the gut or lead to stool that is small, dry, and hard to push out.

2. Medications that commonly cause constipation

Many prescription and overā€‘theā€‘counter medicines list constipation as a side effect.

Common culprits include:

  • Opioid pain medicines (often after surgery or for chronic pain).
  • Some antidepressants.
  • Some blood pressure medicines.
  • Certain antihistamines.
  • Iron supplements.
  • Antacids containing calcium or aluminum.
  • Some antiā€‘seizure medicines.
  • Nausea medicines.

If constipation starts soon after a new medication, that drug might be a contributor.

3. Medical conditions that affect the gut

Sometimes constipation is a symptom of an underlying health issue.

Conditions linked with constipation include:

  • Irritable bowel syndrome (IBS).
  • Diabetes and other metabolic conditions.
  • Low thyroid (hypothyroidism).
  • Neurological disorders (Parkinsonā€™s disease, multiple sclerosis).
  • Brain or spinal cord injury.
  • Pelvic floor dysfunction (muscles donā€™t coordinate well for bowel movements).
  • Celiac disease.
  • Inflammation or structural problems in the bowel (diverticular disease, strictures, anatomic abnormalities).

These can change how nerves, muscles, or hormones control bowel movements, slowing transit through the colon.

4. Mental health, stress, and behavior

The brain and the gut are closely connected.

  • Chronic stress , anxiety, or depression can change gut motility.
  • Eating disorders and very restrictive diets can reduce food and fluid intake.
  • Fear or embarrassment about using public toilets may lead to holding stools.

Over time, repeatedly holding stool can make the rectum less sensitive, worsening constipation.

5. Life stages and hormones

Constipation often shows up at certain times of life.

  • Pregnancy: Hormonal changes and pressure from the growing uterus slow the intestines.
  • Older age: People often move less, drink less, and may take more constipating medicines; the gut can also naturally slow down.

Hormonal shifts can change how quickly the colon moves stool along.

6. More serious but less common causes

These are less common but important to recognize.

  • Intestinal obstruction (blockage) from tumors, severe narrowing, or severe fecal impaction.
  • Colon or rectal cancer.
  • Severe anatomic problems of the bowel.

Warning signs that need urgent medical attention include:

  • Blood in or on the stool.
  • Unexplained weight loss.
  • Severe or constant abdominal pain.
  • New, persistent constipation, especially in older adults.

7. How constipation is defined

Different people have different ā€œnormal,ā€ but constipation usually means:

  • Fewer than three bowel movements per week.
  • Hard, dry, or lumpy stools.
  • Straining or feeling that you cannot fully empty.

Some people may go daily but still feel constipated because stool is hard and difficult to pass.

8. Quick checklist: common triggers

If youā€™re wondering ā€œwhatā€™s causing my constipation?ā€ think through:

  1. Have I changed my diet recently (less fiber, more processed food, more dairy)?
  2. Am I drinking enough water during the day?
  3. Have I been less active than usual?
  4. Did I start any new medicines or supplements?
  5. Am I traveling or under unusual stress?
  6. Do I have any longā€‘term conditions (diabetes, thyroid issues, IBS, neurological disease)?

When to see a doctor

You should seek medical advice if you:

  • Have constipation lasting more than a few weeks despite lifestyle changes.
  • Notice blood in your stool or black, tarry stools.
  • Have severe pain, vomiting, or canā€™t pass gas.
  • Have unexplained weight loss or a strong family history of colon cancer.

These signs can point to something more serious than simple constipation.

Information gathered from public forums or data available on the internet and portrayed here.