Constipation: Causes, Relief and When to Worry

What counts as constipation

There is no single "normal" number of bowel movements. Anything from three times a day to three times a week can be normal for you. Constipation is a change from your usual pattern or any of the following:

• fewer than three stools a week
• hard, dry or lumpy stools (types 1 and 2 on the Bristol Stool Chart)
• straining, or feeling blocked at the bottom
• a feeling that you have not fully emptied
• needing to press around the anus or vagina, or use a finger, to pass stool

Constipation is chronic when symptoms are present for at least 3 months.

Constipation symptoms

• fewer bowel movements than usual
• hard, pellet-like stools
• straining and pain on passing stool
• bloating, cramping and a full feeling
• loss of appetite and mild nausea
• small amounts of bright red blood on the toilet paper from hemorrhoids or a small tear

Common causes of constipation

Lifestyle causes

• Low fiber intake: most adults eat about half the recommended 25 to 35 grams a day.
• Not drinking enough: stool absorbs water in the colon, so dehydration makes it harder.
• Lack of movement: activity helps the bowel contract. Bed rest and long journeys slow it.
• Ignoring the urge: holding on teaches the rectum to ignore signals, and stools dry out.
• Changes in routine: travel, shift work and new diets.

Medicines and supplements

• Opioid painkillers (codeine, oxycodone, morphine): very commonly cause constipation
• iron and calcium supplements
• antacids containing aluminum or calcium
• anticholinergic medicines, including some for bladder control, older antihistamines and tricyclic antidepressants
• some blood pressure medicines (verapamil and other calcium channel blockers)
• anti-nausea medicines such as ondansetron
• overuse of stimulant laxatives over many years

Medical causes

• Irritable bowel syndrome with constipation: bloating and abdominal pain that eases after a bowel movement, often alternating with loose stools.
• Pelvic floor dysfunction: the muscles that should relax during a bowel movement tighten instead, so you strain despite soft stool.
• Hypothyroidism: slows the gut, with tiredness, weight gain and feeling cold.
• Diabetes: nerve damage can slow the bowel.
• High calcium levels, from overactive parathyroid glands or cancer.
• Neurological conditions: Parkinson's disease, multiple sclerosis and spinal cord injury.
• Pregnancy: hormones relax the gut muscle and the growing womb presses on the bowel.

Serious causes

• Colorectal cancer: a persistent change in bowel habit, especially with blood, anemia or weight loss, in people over 50 or with a family history.
• Bowel obstruction: from adhesions after surgery, hernias, twisting of the bowel or tumors.
• Fecal impaction: a large mass of hard stool stuck in the rectum, common in frail older adults and people on opioids.

When to worry about constipation

Most constipation is harmless. These signs need medical review:

• Blood: in or on the stool, or black stools
• Weight loss you cannot explain
• New constipation after age 50, or a change in bowel habit lasting more than 3 weeks
• Family history of bowel cancer or inflammatory bowel disease
• Anemia found on a blood test
• Severe or worsening pain, a swollen belly or vomiting
• Thin, pencil-like stools that persist
• No improvement after 2 weeks of self-help and laxatives

Bright red blood only on the toilet paper after straining is usually from hemorrhoids or an anal fissure, but persistent bleeding still needs checking.

How doctors diagnose constipation

The doctor will ask how often you go, what the stools look like, whether you strain, your diet, fluids, medicines and any red flags. They may examine your belly and do a rectal exam to check for impacted stool, hemorrhoids, fissures and how well the pelvic floor muscles relax.

Tests are not needed for most people. Depending on your age and symptoms, they may include:

• blood tests: blood count, thyroid function, calcium and blood sugar
• a fecal immunochemical test (FIT) for hidden blood
• colonoscopy if there are red flags or you are due for bowel cancer screening
• anorectal manometry and balloon expulsion test for suspected pelvic floor dysfunction
• a colonic transit study to measure how fast stool moves

How to relieve constipation

Fast constipation relief

For quick relief of an occasional episode:

1. Drink a warm drink in the morning. Coffee stimulates the colon in many people.
2. Get moving: a brisk 10 to 20 minute walk.
3. Use a footstool: raise your knees above your hips, lean forward and relax your belly. This straightens the angle of the rectum.
4. Try an osmotic laxative such as polyethylene glycol (PEG). It usually works within 1 to 3 days.
5. A glycerin or bisacodyl suppository often works within 15 to 60 minutes.
6. A stimulant laxative such as senna or bisacodyl at bedtime usually works overnight.

Follow the label dose for any laxative.

Diet and fluids

• Increase fiber gradually to 25 to 35 grams a day over 2 to 3 weeks to limit gas: whole grains, beans, lentils, vegetables and fruit.
• Kiwi fruit (two a day) and prunes (about 50 g, or 6 to 7 prunes, twice a day) have good evidence for chronic constipation.
• A psyllium fiber supplement helps many people. Take it with plenty of water.
• Drink enough to keep urine pale yellow.

Habits

• Go when you feel the urge. Do not delay.
• Give yourself time after breakfast, when the bowel is naturally most active.
• Avoid prolonged straining or sitting on the toilet scrolling for long periods.

Laxatives: which type?

Avoid magnesium-based laxatives if you have kidney disease. Ask a doctor before using laxatives in children or regularly for more than a week.

Prescription treatments

For chronic constipation that does not respond, doctors may prescribe medicines that draw fluid into the gut or stimulate movement (such as linaclotide, lubiprostone or prucalopride), specific treatments for opioid-induced constipation, or biofeedback therapy for pelvic floor dysfunction.

Constipation in specific groups

• Children: common during potty training and starting school. Painful stools lead to holding on, which worsens it. Polyethylene glycol is often used under medical advice. See a doctor if a child is in pain, soiling, or constipated from birth.
• Pregnancy: fiber, fluids and activity first. Bulk-forming laxatives and polyethylene glycol are usually considered safe; check with your midwife or doctor.
• Older adults: more prone because of medicines, less activity and lower fluid intake. Watch for impaction and confusion.
• On opioids: start a laxative at the same time as the opioid, usually an osmotic plus a stimulant.

Preventing constipation

• Eat high-fiber foods at every meal.
• Drink water through the day.
• Be active for at least 30 minutes most days.
• Keep a regular toilet routine and respond to the urge.
• Review medicines that cause constipation with your doctor.

Frequently asked questions

When should I worry about constipation?

See a doctor if you notice blood in your stool, black stools, weight loss, vomiting, severe or worsening pain, a swollen belly, or if constipation is new after age 50 or lasts more than 3 weeks. Seek emergency care if you cannot pass stool or gas and are vomiting.

How long is too long without a bowel movement?

Going more than 3 days without a bowel movement is generally considered constipation, but discomfort matters more than the count. If you have gone a week, or have pain, bloating or vomiting, contact a doctor. People on opioids should not go more than 3 days without treatment.

What is the fastest way to relieve constipation?

A glycerin or bisacodyl suppository usually works within an hour. A stimulant laxative such as senna taken at bedtime works overnight. A warm drink, a short walk and sitting with your feet on a stool can also help things move. Follow label doses.

Can constipation be a sign of something serious?

Usually it is not. But constipation with blood in the stool, weight loss, anemia or a lasting change in bowel habit can be a sign of bowel cancer, especially after 50. Constipation with vomiting and a swollen belly can mean a bowel obstruction.

Is it safe to take laxatives every day?

Bulk-forming and osmotic laxatives such as psyllium and polyethylene glycol are generally safe for long-term use under medical guidance. Stimulant laxatives are safe for occasional use and, when needed, for longer periods with a doctor's advice. Discuss daily use with your doctor.

What foods help constipation?

Prunes, kiwi fruit, pears, apples with the skin, beans, lentils, oats, wholegrain bread, bran and vegetables all add fiber. Increase them gradually and drink plenty of water. Reduce heavily processed foods, which are often low in fiber.