From the Guidelines
Baclofen toxicity symptoms include visual and auditory hallucinations, anxiety, agitation, delirium, fever, tremors, tachycardia, and seizures, which can be life-threatening, especially with abrupt withdrawal of intrathecal baclofen 1.
Key Symptoms
- Visual and auditory hallucinations
- Anxiety
- Agitation
- Delirium
- Fever
- Tremors
- Tachycardia
- Seizures
Management Considerations
Perioperative management of patients receiving intrathecal baclofen should be planned with input from a specialist in this area to avoid potentially life-threatening withdrawal symptoms, including high fever, altered mental status, rebound spasticity, and muscle rigidity that can lead to rhabdomyolysis, multiorgan failure, and death 1.
Clinical Implications
Abrupt discontinuation of baclofen in patients who take it long-term can lead to significant withdrawal symptoms, emphasizing the need for careful planning and management in the perioperative period or when adjusting baclofen doses 1.
From the FDA Drug Label
ADVERSE REACTIONS The most common is transient drowsiness (10% to 63%). In one controlled study of 175 patients, transient drowsiness was observed in 63% of those receiving baclofen compared to 36% of those in the placebo group. Other common adverse reactions are dizziness (5% to 15%), weakness (5% to 15%) and fatigue (2% to 4%) Others reported: Neuropsychiatric:Confusion (1% to 11%), headache (4% to 8%), insomnia (2% to 7%); and, rarely, euphoria, excitement, depression, hallucinations, paresthesia, muscle pain, tinnitus, slurred speech, coordination disorder, tremor, rigidity, dystonia, ataxia, blurred vision, nystagmus, strabismus, miosis, mydriasis, diplopia, dysarthria, epileptic seizure Cardiovascular:Hypotension (0% to 9%). Rare instances of dyspnea, palpitation, chest pain, syncope. Gastrointestinal:Nausea (4% to 12%), constipation (2% to 6%); and, rarely, dry mouth, anorexia, taste disorder, abdominal pain, vomiting, diarrhea, and positive test for occult blood in stool Genitourinary:Urinary frequency (2% to 6%); and, rarely, enuresis, urinary retention, dysuria, impotence, inability to ejaculate, nocturia, hematuria. Other:Instances of rash, pruritus, ankle edema, excessive perspiration, weight gain, nasal congestion.
Baclofen toxicity symptoms may include:
- Neuropsychiatric symptoms: confusion, headache, insomnia, euphoria, excitement, depression, hallucinations, paresthesia, muscle pain, tinnitus, slurred speech, coordination disorder, tremor, rigidity, dystonia, ataxia, blurred vision, nystagmus, strabismus, miosis, mydriasis, diplopia, dysarthria, epileptic seizure
- Cardiovascular symptoms: hypotension, dyspnea, palpitation, chest pain, syncope
- Gastrointestinal symptoms: nausea, constipation, dry mouth, anorexia, taste disorder, abdominal pain, vomiting, diarrhea
- Genitourinary symptoms: urinary frequency, enuresis, urinary retention, dysuria, impotence, inability to ejaculate, nocturia, hematuria
- Other symptoms: rash, pruritus, ankle edema, excessive perspiration, weight gain, nasal congestion 2
From the Research
Baclofen Toxicity Symptoms
Baclofen overdose can cause a range of severe symptoms, including:
- Coma [(3,4,5,6,7)]
- Respiratory depression [(3,4,5)]
- Autonomic disturbances [(4,5)]
- Seizures [(3,4,6,7)]
- Hyporeflexia [(3,4,6)]
- Flaccidity [(3,5)]
- Hypotension [(3,6)]
- Hypertension [(4,6)]
- Bradycardia [(3,4,7)]
- Tachycardia 6
- Delirium [(3,6,7)]
- Hallucinations [(3,7)]
- High fever 3
Severity of Symptoms
The severity of symptoms can vary depending on the dose of baclofen ingested, with higher doses (> 200 mg) associated with more severe symptoms, including:
- Coma 6
- Delirium 6
- Seizures 6
- Prolonged length of stay in hospital 6
- Increased need for ICU admission 6
- Mechanical ventilation 6
Diagnosis and Treatment
Diagnosis of baclofen overdose can be challenging, especially without anamnestic information 7. Treatment typically involves supportive care, including: