Does Lioresal (baclofen) cause constipation?

Does Baclofen (Lioresal) Cause Constipation?

Yes, baclofen can cause constipation and, in rare cases, severe gastrointestinal complications including intestinal pseudo-obstruction. 1, 2, 3

Mechanism and Evidence

Baclofen is a GABA-B receptor agonist that affects the gastrointestinal tract through its action on the enteric nervous system. 1 The drug has been specifically identified in clinical practice guidelines as one of several medications associated with severe dysmotility that typically improves with dose reduction or discontinuation. 1

Documented Gastrointestinal Effects

• Constipation is a recognized side effect of both oral and intrathecal baclofen administration. 1, 3
• Intestinal pseudo-obstruction has been reported as a rare but serious complication, with documented cases requiring baclofen withdrawal for resolution. 2, 4
• The gastrointestinal effects appear to be dose-dependent and reversible upon medication discontinuation or dose reduction. 2, 4

Clinical Context and Severity

While baclofen is FDA-approved and widely used for spasticity management, clinicians must weigh its gastrointestinal risks:

• In stroke rehabilitation, oral baclofen has demonstrated efficacy for spasticity but may cause significant sedation and has less impact on spasticity compared to other conditions. 1
• The drug has been studied in alcohol use disorder with liver disease, where it showed acceptable safety, though patients with hepatic encephalopathy were excluded due to concerns about mental status impairment. 1
• Long-term studies spanning up to six years found that 20% of patients required dosage reduction due to side effects, though the specific breakdown of gastrointestinal versus other adverse effects was not detailed. 5

Important Clinical Considerations

When prescribing baclofen, monitor for:

• Development of constipation, particularly in patients with pre-existing bowel dysfunction 1, 3
• Signs of intestinal obstruction (abdominal distension, absence of bowel movements, nausea) 2, 4
• The need for prophylactic bowel regimens in high-risk patients 6

Common pitfall: Failing to recognize that baclofen-induced constipation can progress to pseudo-obstruction if not addressed early. 2, 4 The condition may mimic mechanical obstruction but lacks air-fluid levels on imaging and resolves with drug withdrawal. 2

Adjunctive Use in GERD

Interestingly, baclofen has been studied for reducing transient lower esophageal sphincter relaxations in GERD patients, where it may be used specifically for belch-predominant symptoms or regurgitation. 1, 7 However, its use is often limited by both central nervous system and gastrointestinal side effects. 1 In one study of refractory GERD patients, baclofen at 20 mg three times daily improved symptoms, though four patients reported nausea or drowsiness. 7

Management Approach

If constipation develops on baclofen:

• First-line: Consider dose reduction while maintaining therapeutic efficacy 1, 2
• Second-line: Implement osmotic laxatives (polyethylene glycol, lactulose) or stimulant laxatives (senna, bisacodyl) as prophylaxis 6
• Avoid: Relying solely on stool softeners like docusate, which lack efficacy evidence 6
• Severe cases: Discontinue baclofen if pseudo-obstruction develops 2, 4