Can constipation cause low back pain?

Can Constipation Cause Low Back Pain?

Yes, constipation can cause low back pain, though it is not typically a primary cause of mechanical low back pain and should not be assumed to be the etiology without first ruling out more common musculoskeletal causes and red flag conditions.

Understanding the Relationship

Constipation-related low back pain occurs through several mechanisms:

• Direct anatomical pressure: Severe constipation or fecal impaction can cause distension of the rectosigmoid colon, which may create pressure on adjacent lumbosacral structures and nerves, potentially manifesting as low back discomfort 1.

• Referred visceral pain: Gastrointestinal distension and discomfort from constipation can present as referred pain to the lower back region, particularly in patients with chronic constipation 2.

• Associated with irritable bowel syndrome: Patients with IBS frequently report low back pain as a non-colonic symptom alongside their bowel dysfunction, with studies demonstrating that constipation is a major contributor to pain in these patients 3, 4, 2.

Critical Diagnostic Priorities

Before attributing low back pain to constipation, you must systematically exclude serious pathology:

Immediate red flags requiring urgent evaluation 5, 6, 7:

• Cauda equina syndrome (urinary retention, fecal incontinence, saddle anesthesia, bilateral leg weakness)
• Malignancy indicators (age >50, history of cancer, unexplained weight loss, failure to improve after 1 month)
• Spinal infection (fever, recent infection, IV drug use, immunocompromised status)
• Vertebral compression fracture (older age, osteoporosis, steroid use)

Distinguish from radiculopathy and spinal stenosis 5, 6:

• True radiculopathy presents with leg pain below the knee in a dermatomal distribution, not isolated back or buttock pain
• Spinal stenosis causes neurogenic claudication (leg pain with walking/standing relieved by sitting or spinal flexion)
• Assess for motor deficits, sensory changes, and reflex abnormalities

Clinical Evidence Supporting the Connection

Research in specific populations demonstrates the constipation-back pain relationship:

• Spinal cord injury patients: 58% of patients with complete SCI above L2 suffer from constipation, and one-third develop chronic abdominal pain that may include low back pain 8, 9.

• Comparative pain characteristics: A study comparing spinal cord injury patients with chronic idiopathic constipation found that 81% of SCI patients and 93% of constipation patients reported abdominal pain or discomfort, with similar qualitative descriptions and locations of pain 3.

• IBS-associated back pain: Patients with IBS frequently report low backache as a non-colonic symptom, with constipation identified as a major cause of this pain 4, 2.

Practical Clinical Approach

When constipation is the suspected cause 1:

1. Assess constipation severity: Determine frequency of bowel movements, presence of impaction, and associated symptoms (abdominal distension, pain, bloating)

2. Identify contributing factors: Review medications (opioids, anticholinergics, antacids), assess for metabolic causes (hypercalcemia, hypokalemia, hypothyroidism, diabetes)

3. Initial management for constipation-related back pain:

   • Stimulant laxatives (senna, bisacodyl 10-15 mg, 2-3 times daily) to increase bowel motility
   • Osmotic laxatives (polyethylene glycol, lactulose, magnesium hydroxide) if stimulants insufficient
   • Increase fluid intake and physical activity when appropriate
   • If impaction present: glycerine suppositories or manual disimpaction

4. Reassess pain after bowel function normalizes: If low back pain persists despite resolution of constipation, pursue standard evaluation for nonspecific low back pain

Common Pitfalls to Avoid

• Do not routinely image for nonspecific low back pain: Imaging does not improve outcomes and may lead to unnecessary interventions unless red flags are present 6, 7.

• Do not assume constipation is the cause without proper evaluation: Most low back pain is musculoskeletal in origin; constipation should be considered contributory only after excluding more common causes 5, 6.

• Do not overlook medication-induced constipation: Opioid analgesics are the most common cause of constipation in patients with chronic pain, creating a potential cycle where pain treatment worsens constipation, which may worsen pain 1.

• Recognize that anatomic findings on imaging correlate poorly with symptoms: Degenerative changes on lumbar imaging are usually nonspecific and do not necessarily explain pain 5.