Clonazepam
5-(2-chlorophenyl)-7-nitro-1,3-dihydro-1,4-benzodiazepin-2-one
Also known as: Klonopin · Antelepsin · Clonagin · Clonapam · Clonax · Clonex · Diocam · Epitril · Iktorivil · Kenoket · Kriadex · Neuryl · Paxam · Rivatril · Rivotril · Solfidin · Linotril · clonazepamum · Ro-5-4023
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 |
|---|---|---|---|---|---|
| Adjunctive medication in the treatment of seizures | 1-2 mg/kg PO q12h | PO | q12h | — | 🌎 NA |
| Adjunctive medication in the treatment of seizures | 0.5 mg/kg PO two to three times a day | PO | q8-12h | — | 🌎 NA |
| Anxiolytic | 0.05-0.25 mg/kg PO q12-24h | PO | q12-24h | — | 🌎 NA |
| Anxiolytic | 0.1-1 mg/kg PO two to three times a day | PO | q8-12h | — | 🌎 NA |
| Muscular hypertonicity (episodic falling) / Anxiolytic | 0.5 mg/kg | PO | q8-12h | — | 🌍 EU |
- Adjunctive medication in the treatment of seizures: May need to lower phenobarbital dose by 10-20%
- Muscular hypertonicity (episodic falling) / Anxiolytic: Suggested starting dose but there is a wide range of recommendations.
Cats
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Anxiolytic | 0.05-0.25 mg/kg PO q12-24h | PO | q12-24h | — | 🌎 NA |
| Anxiolytic | 0.02-0.2 mg/kg PO once to two times a day | PO | q12-24h | — | 🌎 NA |
| Anxiolytic | 0.1-0.2 mg/kg PO as needed or up to two times a day | PO | PRN or q12h | — | 🌎 NA |
| Adjunctive medication in the treatment of seizures | Starting dose is 0.5 mg (total dose) PO q12-24h | PO | q12-24h | — | 🌎 NA |
| Adjunctive medication in the treatment of seizures | 1/8th to 1/4 of a 0.5 mg tablet PO two to three times daily | PO | q8-12h | — | 🌎 NA |
| Anxiolytic / Hyperaesthesia / Epilepsy | 0.5 mg/cat | PO | q12-24h | — | 🌍 EU |
- Adjunctive medication in the treatment of seizures: Anecdotally more effective for maintenance and to decrease cluster seizures; acute hepatic necrosis possible
- Anxiolytic / Hyperaesthesia / Epilepsy: Suggested starting dose but there is a wide range of recommendations.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Clonazepam is a potent, long-acting benzodiazepine used in veterinary medicine primarily as an adjunctive anticonvulsant and anxiolytic.
Clinical Pearl: In dogs, its utility as a long-term maintenance anticonvulsant is severely limited because they rapidly develop tolerance to its antiepileptic effects (often within 1 to 4 weeks). This is due to receptor downregulation and altered pharmacokinetics. Therefore, it is much better suited for short-term pulse therapy or the management of cluster seizures.
- In cats, it can be used for longer-term adjunctive treatment of epilepsy or anxiety. While idiosyncratic acute hepatic necrosis is a known risk with oral benzodiazepines in cats (most notably diazepam), it is generally considered less likely to occur with clonazepam, though monitoring is still required.
- Clonazepam is a Schedule IV (C-IV) controlled substance due to its potential for human abuse and dependence.
Mechanism of action
Clonazepam acts as a positive allosteric modulator at the GABA-A receptor complex in the central nervous system.
- It binds to specific benzodiazepine receptors (located primarily in the limbic, thalamic, and hypothalamic regions) → enhances the affinity of the receptor for the inhibitory neurotransmitter gamma-aminobutyric acid (GABA).
- This increases the frequency of chloride channel opening → influx of chloride ions → cellular hyperpolarization → decreased neuronal excitability.
- Additional postulated mechanisms include antagonism of serotonin and diminished release or turnover of acetylcholine in the CNS.
Safety & warnings
Contraindications
- Hypersensitivity to clonazepam or other benzodiazepines
- Significant liver disease or dysfunction
- Acute narrow-angle glaucoma
- Myasthenia gravis (may exacerbate weakness)
- Marked CNS depression
- Respiratory depression
- Severe muscle weakness
- Hepatic impairment (may worsen hepatic encephalopathy)
Adverse effects
- Sedation and lethargy
- Ataxia (incoordination)
- Paradoxical excitement, hyperactivity, or vocalization
- Increased salivation
- Gastrointestinal upset (vomiting, diarrhea, constipation)
- Dogs: Rapid tolerance to anticonvulsant effects
- Cats: Polyphagia, potential for acute hepatic necrosis (rare)
- Respiratory suppression (at higher doses)
- Acute hepatic necrosis (idiosyncratic in cats)
- Tolerance development
Precautions
Do not discontinue therapy abruptly, especially in patients on chronic or high-dose therapy, as this may precipitate withdrawal signs or status epilepticus; taper the dose gradually. Use with caution in nursing dams, as benzodiazepines can enter milk and accumulate to toxic levels in neonates. Monitor cats closely for signs of hepatotoxicity.
Drug interactions
May increase clonazepam levels by inhibiting its metabolism.
May decrease the metabolism of benzodiazepines, increasing their effects.
Additive CNS depression; may cause profound sedation or respiratory depression.
May decrease the metabolism of benzodiazepines.
May decrease clonazepam concentrations via hepatic enzyme induction.
May decrease clonazepam concentrations.
May decrease clonazepam concentrations.
May induce hepatic microsomal enzymes and decrease the pharmacologic effects of benzodiazepines.
Inhibition of CYP450 enzymes may decrease clonazepam clearance, increasing its plasma levels and risk of toxicity.
Additive sedation and respiratory depression.
Monitoring
- Clinical efficacy (seizure frequency, anxiety levels)
- Adverse effects (sedation, ataxia, paradoxical excitement)
- Therapeutic blood levels (reported target: 0.015-0.07 mcg/mL)
- Cats: Baseline and periodic liver function tests
- Degree of sedation and ataxia
- Respiratory rate and effort
- Hepatic function panel (especially in cats)
- Clinical response (seizure frequency, muscle tone, or behavioral changes)
Pharmacokinetics
Half-life
Absorption
In dogs, oral bioavailability is variable (20-60%) but absorption is rapid. In humans, it is well absorbed from the GI tract with peak serum levels occurring about 3 hours after oral dosing.
Distribution
Highly lipophilic; rapidly crosses the blood-brain barrier and placenta. Protein binding in dogs is approximately 82%.
Metabolism
Metabolized in the liver to several metabolites. In dogs, clonazepam exhibits saturation kinetics, meaning elimination rates are dose-dependent.
Elimination
Metabolites are excreted primarily in the urine.
Overdose
Overdoses commonly cause profound sedation, depression, and ataxia.
- Paradoxical Reactions: Some animals may exhibit paradoxical signs such as hyperactivity, disorientation, agitation, and vocalization. Paradoxical excitation can be treated with a mild sedative, such as diphenhydramine.
- Management: Emesis is generally NOT indicated due to the risk of rapid CNS depression and aspiration. Mild to moderate overdoses can often be monitored at home if the animal is rousable and not showing paradoxical signs. Keep the animal confined and minimize stimulation.
- Severe Toxicity: Massive overdoses can lead to respiratory depression or hypotension. Flumazenil (a specific benzodiazepine antagonist) can be used to reverse severe respiratory or CNS depression. Because flumazenil has a short half-life, multiple doses may be required.
Available products
Formulations
- Oral tablets
- Orally disintegrating tablets (ODT)
- Compounded oral suspension
- 0.25 mg tablet
- 0.5 mg tablet
- 1.0 mg tablet
- 2 mg tablet
- 500 mcg tablet
- 500 mcg/5 ml oral solution
- 2 mg/5 ml oral solution
Human-labeled
- Clonazepam Oral Tablets: 0.5 mg, 1 mg, & 2 mg (Klonopin, generic)
- Clonazepam Orally Disintegrating Tablets: 0.125 mg, 0.25 mg, 0.5 mg, 1 mg & 2 mg (Klonopin Wafers, generic)
- Linotril
- Rivotril
Regulatory status
POM (Prescription Only Medicine). Subject to national controlled drug regulations.
POM. Prescriptions are subject to controlled drug requirements.
No regulatory data for: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Tablets should be stored in airtight, light-resistant containers at room temperature. Compounded oral suspensions (0.1 mg/mL in Ora-Plus/Ora-Sweet) retain >90% potency for 60 days when stored at 5°C or 25°C, but must be protected from light.
Client information
- Consistency is Key: A major factor in anticonvulsant therapy failure is a lack of compliance. It is very important to give doses regularly at the prescribed times.
- Do Not Stop Abruptly: Never stop this medication suddenly without your veterinarian's guidance. Abrupt withdrawal can trigger severe, life-threatening continuous seizures (status epilepticus). If the medication needs to be stopped, your vet will provide a tapering schedule.
- Side Effects: Mild sleepiness and clumsiness are common when starting the medication but often improve. If your pet becomes unusually hyperactive or agitated, contact your vet.
- Cat Owners: Watch your cat closely for a lack of appetite, vomiting, or yellowing of the whites of the eyes or gums (jaundice). These can be signs of a rare but serious liver issue. Contact your veterinarian immediately if you notice these signs.
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.