Section 09 · Monograph

Baclofen

Reviewed Nov 2026FDA label

LioresalGABA-B agonist

Indications

Management of spasticity, particularly flexor spasms and concomitant pain, clonus, and muscular rigidity resulting from multiple sclerosisFDA-labeled
Management of spasticity resulting from spinal cord injuries or spinal cord diseasesFDA-labeled
Intrathecal (Lioresal Intrathecal): severe spasticity of spinal or cerebral origin in patients unresponsive to or intolerant of oral baclofen or other oral therapyFDA-labeled
Off-label but widely used for spasticity and cramping in ALSFDA-labeled

Alcohol use disorder — used off-label to reduce craving and support abstinenceOff-label
Gastroesophageal reflux disease (GERD) — reduces transient lower esophageal sphincter relaxationsOff-label
Hiccups (intractable)Off-label
Trigeminal neuralgia as adjunctive therapyOff-label

GABA-B receptor agonist at spinal and supraspinal sites
Inhibits both monosynaptic and polysynaptic reflexes at the spinal cord level by hyperpolarizing afferent terminals
Reduces release of excitatory neurotransmitters, decreasing spasticity

Oral: initiate at 5 mg orally 3 times daily; titrate every 3 days in 5 mg increments per dose as needed, up to a usual maximum of 80 mg/day (20 mg 4 times daily) though some patients require higher doses
Intrathecal: highly individualized; test dose via lumbar puncture (25-50 mcg) then chronic infusion via implanted pump, typically starting 12 hours after a positive test dose response
Do not abruptly discontinue oral or intrathecal baclofen — taper oral therapy and never allow intrathecal pump reservoir to run dry (risk of life-threatening withdrawal)

Renal impairment: reduce dose and titrate more cautiously; baclofen is renally eliminated and impairment increases risk of toxicity/encephalopathy

Known hypersensitivity to baclofen
Intrathecal baclofen: not for intravenous, intramuscular, subcutaneous, or epidural administration

CNS depressants (opioids, benzodiazepines, alcohol) — additive sedation and respiratory depression risk
Antihypertensives — may potentiate hypotensive effects
Tricyclic antidepressants — may enhance muscle hypotonia
MAO inhibitors — limited data, use caution

Common: drowsiness/sedation
Common: dizziness
Common: weakness
Common: fatigue
Common: nausea
Common: headache
Common: confusion (especially in elderly or with renal impairment)
Serious: abrupt withdrawal syndrome (hallucinations, seizures, high fever, rebound spasticity — can be life-threatening) with sudden discontinuation of oral or intrathecal therapy
Serious: intrathecal pump/catheter complications (infection, granuloma, malfunction leading to overdose or withdrawal)
Serious: respiratory depression/CNS depression, particularly intrathecal overdose

Renal function, particularly before and during oral therapy given renal elimination
Clinical response and tolerability with dose titration
For intrathecal therapy: pump function, catheter integrity, infusion site for infection
Signs/symptoms of withdrawal (fever, altered mental status, exaggerated rebound spasticity) if any interruption in delivery is suspected
Mental status in elderly patients or those with renal impairment (risk of encephalopathy)

Animal studies showed adverse fetal effects at high doses; limited human data — use if benefits outweigh risks
Baclofen is present in human milk in small amounts; monitor breastfed infant for sedation