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Digestive health MediBilbao Salud

Can Constipation Cause Back Pain? The Link, Other Causes and How to Get Relief

Constipation and lower back pain often appear together, and many people wonder whether one causes the other. A backed-up bowel can cause a dull ache that spreads to the lower back, and some back problems and medicines can, in turn, make constipation worse. Sometimes, however, both symptoms come from a third cause that needs attention. This guide explains the link and gives practical dietary advice from a nutrition point of view, together with the warning signs to watch for.

Topic
Nutrition
Updated
Reading time
6 minutes
Reviewed by
Dr. Itziar Gotxi Erezuma · Medical doctor (ENT) · Bizkaia Medical Association no. 484809757

How constipation can cause back pain

Constipation means passing stools less often than usual, typically fewer than three times a week, or stools that are hard, lumpy and difficult to pass. When stool stays in the large bowel, it loses water, becomes harder and stretches the bowel wall. The lower part of the bowel sits in front of the lower spine and pelvis, and its nerve supply enters the spinal cord at levels shared with the lower back.

As a result, pressure and stretching in the bowel can be felt as a dull ache in the lower back, sometimes on the left side where the last part of the colon lies. Trapped gas adds to the stretching. Straining on the toilet also increases pressure in the abdomen and can strain back muscles. Typically, the back discomfort improves after a bowel movement.

When back pain causes constipation

  • Painkillers: opioid medicines such as codeine, tramadol and morphine slow the bowel and are a very common cause of constipation in people with back pain.
  • Less movement: being less active because of pain slows bowel transit.
  • Pain when straining: people may delay going to the toilet because pushing hurts their back.
  • Nerve compression: rarely, severe compression of the nerves at the base of the spine (cauda equina syndrome) affects bowel and bladder control. This is an emergency (see the warning signs below).

Other conditions that cause both symptoms

  • Irritable bowel syndrome (IBS): abdominal pain, bloating and changes in bowel habit, often with back pain. See diet for IBS.
  • Kidney stones or kidney infection: pain in the side or back (flank), often coming in waves, with urinary symptoms or fever.
  • Gynaecological conditions: endometriosis and ovarian cysts can cause pelvic and back pain together with bowel symptoms.
  • Diverticulitis: pain usually on the lower left side, with fever and change in bowel habit.
  • Pregnancy: hormonal changes slow the bowel and the growing baby loads the back.
  • Less commonly: an underactive thyroid, high calcium levels, and bowel tumours, especially in people over 50 with a recent change in bowel habit.

Diet for constipation-related back pain

Most constipation improves with diet and lifestyle. A gradual approach avoids extra bloating:

  • Fibre: aim for about 30 g a day for adults. Good sources are wholegrain bread and cereals, oats, beans and lentils, vegetables, fruit with the skin, and seeds such as linseed. Increase slowly over two to three weeks.
  • Soluble fibre for softer stools: oats, psyllium (ispaghula), linseed, apples and pears.
  • Prunes and kiwis: two kiwis a day or a handful of prunes have good evidence for improving stool frequency.
  • Fluids: drink regularly through the day, about 6 to 8 glasses, more in hot weather or with exercise. Fibre works better with enough fluid.
  • Regular meals: eating breakfast triggers a natural reflex that moves the bowel.
  • Watch for triggers: large amounts of processed food, very low-fibre diets and some supplements (iron, calcium) can worsen constipation.

For a full list of foods, see food for constipation and foods high in fiber. People with IBS may need a different approach, sometimes with a dietitian-guided low FODMAP diet.

Toilet routine, movement and posture

  • Go when you feel the urge; do not delay.
  • Allow time after breakfast, when the bowel is most active.
  • Raise your feet on a small stool so that your knees are above your hips, lean forward and relax the tummy: this straightens the angle of the rectum.
  • Avoid long straining; it strains the pelvic floor and back.
  • Walk or exercise daily; gentle movement stimulates the bowel and helps back pain.
  • Gentle back and hip stretches can ease muscle tension, for example knee-to-chest stretches.

Laxatives and pain relief

If diet and lifestyle changes are not enough after a few days, a pharmacist can recommend a laxative. Bulk-forming laxatives (such as ispaghula) are usually tried first, followed by osmotic laxatives (such as macrogol). Stimulant laxatives are useful for short periods. People taking opioid painkillers often need a laxative from the start.

For back pain itself, paracetamol or anti-inflammatories (if suitable) are less constipating than codeine. Heat on the lower back and staying active are recommended for most simple back pain. See lower back strain for exercises.

When to seek medical help

  • Call emergency services or go to A&E if back pain comes with numbness around the bottom or genitals, new difficulty passing urine or controlling the bladder or bowel, or weakness in both legs.
  • Fever, severe abdominal pain or a swollen, hard abdomen.
  • Blood in the stool or black stools.
  • Unexplained weight loss or tiredness.
  • A change in bowel habit lasting more than three weeks, especially over the age of 50.
  • Pain in the side with urinary symptoms or blood in the urine.
  • Constipation that does not improve with laxatives, or no bowel movement and no wind.

Key points to remember

  • Constipation can cause a dull lower back ache that eases after a bowel movement.
  • Back pain and strong painkillers can also cause constipation.
  • Fibre, fluids, regular meals, movement and a good toilet posture usually help.
  • Back pain with numbness in the saddle area or bladder changes is an emergency.

Questions about constipation and back pain

These answers are general information and do not replace an examination or individual medical advice.

Can constipation cause lower back pain?

Yes. A full bowel and trapped gas stretch the bowel, and the discomfort can be felt as a dull ache in the lower back.

Where is back pain from constipation felt?

Usually in the lower back, in the centre or on one side, often with bloating and abdominal discomfort.

Does back pain from constipation go away after a bowel movement?

It usually improves once the bowel empties. If it does not, another cause is more likely.

Can a slipped disc cause constipation?

Indirectly, through less movement and painkillers. Severe nerve compression affecting bowel control is rare and needs emergency care.

What should I eat to relieve constipation?

Increase fibre gradually with wholegrains, oats, beans, vegetables, fruit, kiwis or prunes, and drink enough fluids.

When should I worry about back pain and constipation?

Seek urgent help for numbness in the saddle area, bladder or bowel control changes, leg weakness, fever or blood in the stool.

Sources

  1. NHS · Constipation
  2. NIDDK (NIH) · Constipation
  3. NHS · Back pain
  4. NHS · Irritable bowel syndrome (IBS)
  5. NHS · Kidney stones

This guide is for general information and does not replace medical advice. How a problem is diagnosed and treated depends on your examination and medical history. If you think you have an emergency, contact your local emergency services.