Baclofen toxicity

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Background

Tablets of Baclofen
  • Baclofen is a synthetic derivative of GABA used to reduce spasticity in conditions such as multiple sclerosis and cerebral palsy, or to reduce muscular spasm in lower back pain.
  • At therapeutic doses, baclofen acts as a GABA-B receptor agonist in the spinal cord, causing inhibition of muscular tone.
  • At higher doses, baclofen loses selectivity and can cause sedation.
  • Primarily (80%) excreted by the kidneys
    • Dosage must be reduced in renal dysfunction and should be avoided with GFR < 30 mL/min/1.73 m2.
    • Patients on chronic therapy may become toxic with new AKI.

Clinical Features

  • Nausea and vomiting
  • Depressed level of consciousness
  • Delirium
  • Seizures
    • Tonic-clonic
    • Non-convulsive status epilepticus
  • Myoclonus
  • Airway compromise and respiratory failure
  • Hypothermia
  • Hypotension
  • Bradycardia and conduction abnormalities

Differential Diagnosis

Sedative/hypnotic toxicity

Also consider co-ingestion with intentional overdose

Evaluation

  • Diagnosis of exclusion, based on history
    • Baclofen level can be measured but is not clinically useful
  • In patients with intrathecal baclofen pump:
    • Obtain KUB to evaluate pump tubing integrity and placement
    • Consult the managing specialist to interrogate pump

Management

  • Activated charcoal for recent ingestion
  • Supportive care:
    • Respiratory support[1]
    • IV fluids
    • Vasopressors for persistent hypotension
    • Benzodiazepines for seizures or severe myoclonus
      • CNS depressive effects of benzodiazepines will be increased
      • Use the lowest effective dose and be prepared for respiratory depression
  • Hemodialysis for very severe toxicity
    • Probably not beneficial in patients with normal renal function
  • For patients with intrathecal pump:[2]
    • Consult managing specialist
    • Turn off pump
    • Can remove baclofen from pump reservoir and replace with normal saline
    • Consider large volume CSF removal via lumbar puncture to reduce level

Disposition

  • Admit for monitoring until back to neurologic baseline
  • ICU for severe coma, seizures, airway compromise, or respiratory failure

See Also

References

  1. ↑ *Dease NM, et al. Baclofen Toxicity. Updated 2023 Mar 20. In: StatPearls. Treasure Island, FL: StatPearls Publishing; 2025 Jan-. https://www.ncbi.nlm.nih.gov/books/NBK580550. Accessed Oct 13, 2025.
  2. ↑ Watve SV, et al. Management of acute overdose or withdrawal state in intrathecal baclofen therapy. Spinal Cord. 2012 Feb;50(2):107-11. doi: 10.1038/sc.2011.112
  • Jung, M. “Baclofen Overdoses”. Maryland Poison Center, University of Maryland School of Pharmacy. www.mdpoison.com Accessed April 29th, 2014.
  • Nicola Y Leung, Ian M Whyte, Geoffrey K Isbister Baclofen overdose: defining the spectrum of toxicity. Emerg Med Australas: 2006, 18(1);77-82
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