Baclofen
aminomethyl chlorohydrocinnamic acid
Also known as: Lioresal · Kemstro · Baclohexal · Baclon · Baclopar · Baclosal · Baclospas · Balgifen · Clinispas · Lebic · Liotec · Miorel · Neurospas · Nu-Baclo · Pacifen · Vioridon · aminomethyl chlorohydrocinnamic acid · Ba-34647 · baclofenum
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| To treat urinary retention by decreasing urethral resistance | 1-2 mg/kg | PO | q8h | — | 🌎 NA |
| To treat urinary retention by decreasing urethral resistance | 5-10 mg (total dose) | PO | q8h | — | 🌎 NA |
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Baclofen is a centrally acting skeletal muscle relaxant. In veterinary medicine, it is primarily used off-label in dogs to manage functional urinary retention by decreasing urethral sphincter tone.
Clinical Pearls:
- Baclofen has a very narrow margin of safety in animals, and toxicosis is frequently reported due to accidental ingestion of human medications.
- Strictly contraindicated in cats.
- Because it crosses the blood-brain barrier poorly at therapeutic doses, its central effects are limited, but massive overdoses lead to profound CNS depression.
Mechanism of action
Baclofen is a structural analog of the inhibitory neurotransmitter GABA (gamma-aminobutyric acid). It acts primarily as a GABA-B receptor agonist at the spinal cord level.
- Activation of GABA-B receptors → hyperpolarization of primary afferent nerve terminals → inhibition of the release of excitatory neurotransmitters (such as glutamate and aspartate).
- This reduces gamma efferent neuronal activity, decreasing the frequency and amplitude of muscle spasms.
- In the lower urinary tract, it specifically reduces striated sphincter tone in the urethra, facilitating bladder emptying.
Safety & warnings
Contraindications
- Cats (strictly not recommended)
- Hypersensitivity to baclofen
Adverse effects
- Sedation
- Weakness
- Pruritus
- Salivation
- Gastrointestinal distress (nausea, abdominal cramping)
Precautions
Use with caution in patients with seizure disorders and working dogs that must be alert. Do not stop therapy abruptly, as hallucinations and seizures have been reported in humans upon sudden discontinuation. Do not give the intrathecal medication by any other route.
Drug interactions
May cause additive CNS depression
Monitoring
- Efficacy (improvement in urination)
- Adverse effects (sedation, weakness, GI signs)
Pharmacokinetics
Absorption
Rapidly and well absorbed after oral administration, but with wide interpatient variation.
Distribution
Widely distributed; only a small percentage crosses the blood-brain barrier. Crosses the placenta.
Metabolism
Less than 15% of a dose is metabolized by the liver.
Elimination
Eliminated primarily by the kidneys.
Overdose
Baclofen has a narrow margin of safety in dogs.
- Toxicity Thresholds: Deaths have been reported at doses as low as 8 mg/kg. Clinical signs can appear at doses as low as 1.3 mg/kg.
- Clinical Signs: Vomiting, depression, vocalization, hypersalivation, ataxia, hypotonia, muscle twitching, hypothermia, and lethargy. Massive overdoses may cause respiratory depression, coma, or seizures.
- Onset & Duration: Signs can occur 15 minutes to 7 hours post-ingestion and persist for hours to days.
- Treatment:
- In alert patients, empty the gut (emesis/lavage).
- Avoid magnesium-containing saline cathartics (may compound CNS depression).
- Forced fluid diuresis may enhance excretion.
- Mechanical ventilation for respiratory depression.
- Cyproheptadine (1.1 mg/kg PO or PR) may alleviate vocalization and disorientation.
- Atropine may improve ventilation, HR, BP, and body temperature.
- Diazepam for seizures.
- Intravenous Lipid Emulsion (ILE) may be useful as baclofen is lipid-soluble.
Available products
Formulations
- Orally disintegrating tablets
- Intrathecal injection
- Compounded oral suspension
Human-labeled
- Baclofen Tablets: 10 mg & 20 mg (Lioresal, generic)
- Baclofen orally disintegrating tablets: 10 mg & 20 mg (Kemstro)
- Baclofen Intrathecal Injection: 0.05 mg/mL, 500 mcg/mL, 2000 mcg/mL (Lioresal Intrathecal)
Regulatory status
No regulatory data for: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Do not store tablets above 30°C (86°F). Intrathecal product should be stored at room temperature; do not freeze or heat sterilize. Compounded oral suspensions should be protected from light.
Client information
CRITICAL WARNING: Baclofen is highly toxic to pets. Keep all human medications securely out of reach.
- Strictly follow the prescribed dose. Never give more than directed.
- Do not stop abruptly. Sudden discontinuation can cause severe withdrawal signs like seizures. Always consult your veterinarian before stopping the medication.
- Watch for signs of toxicity: Extreme sleepiness, weakness, drooling, vomiting, or unusual vocalizing. Contact a veterinarian or animal poison control immediately if these occur or if an accidental overdose is suspected.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.