Diazepam for Dogs: Side Effects and Seizure Use

Name: Diazepam for Dogs: Side Effects and Seizure Use
Creator: Dr. Zubair Khalid

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-10-03

Diazepam is a fast-acting benzodiazepine that veterinarians use most often to stop seizures in an emergency. The most common diazepam for dogs side effects are sedation, lethargy, and ataxia (wobbliness), and a small number of dogs become unusually excited or anxious instead of calm [1]. This article is educational and is not a substitute for veterinary diagnosis or treatment.

Quick Answer

Sedation, lethargy, and ataxia are the expected side effects of diazepam in dogs, and they usually match the dose and wear off as the drug clears [1].
A rare but real reaction is paradoxical excitation, meaning excessive excitement, anxiety, or aggression instead of calm [1].
Diazepam has a rapid onset of action, which is why it is usually the drug of choice to control status epilepticus and stop seizures in small and large animals [1].
Diazepam is a short-term emergency tool. For ongoing seizure control, veterinarians typically add a maintenance anticonvulsant such as IV phenobarbital [1].
Never give your dog diazepam from your own medicine cabinet or adjust a dose on your own. A veterinarian calculates the dose from your dog's weight and health.

What Diazepam Is and What Veterinarians Use It For

Diazepam belongs to a drug class called benzodiazepines. In dogs, its main job is stopping a seizure that is happening right now. Because diazepam has a rapid onset of action, it is usually the drug of choice to control status epilepticus and stop seizures in small and large animals [1]. Status epilepticus means a seizure that will not stop, or seizures that keep coming back without full recovery in between.

Veterinarians also use diazepam for other purposes. It has been used for behavior disorders and as a muscle relaxant [1]. In cats it has been used as an appetite stimulant, though that use does not apply to dogs [1].

Diazepam is not a stand-alone long-term epilepsy treatment. It works fast but does not last long enough to prevent the next seizure hours later. That is why emergency treatment is paired with a maintenance anticonvulsant. If seizures occur after a second or third dose of diazepam, a continuous rate infusion (CRI) of diazepam may be more effective, especially when titrated on the basis of seizure control and extent of sedation, and a maintenance anticonvulsant such as IV phenobarbital should be started as a preventative [1].

If your dog has a seizure at home, the first priority is safety and calling your veterinarian or an emergency clinic. Our guide on What Can You Do For Dog Having Seizures walks through what to do in those first minutes.

How Diazepam Works in Dogs

Benzodiazepines calm overactive electrical activity in the brain. They boost the effect of GABA, the brain's main inhibitory chemical, which slows down the runaway signaling that produces a seizure. This is why the drug can stop a seizure within minutes when it is given intravenously.

The same brain-slowing effect explains the side effects. When the drug calms the brain and nervous system, dogs get sleepy and unsteady. The effect is dose dependent, so a dog that gets a larger dose for a severe seizure will usually look more sedated afterward.

Diazepam also relaxes muscles, which adds to the wobbly, loose-limbed appearance some dogs have after treatment [1]. Most of this settles as the drug is cleared from the body.

Dosing Basics: Who Decides, How It Is Given, and Missed Doses

Who decides the dose

Only a veterinarian decides the dose. Diazepam dosing depends on your dog's weight, the reason it is being given, the route used, and how your dog responds. Never use a dose you found online, and never give your dog diazepam prescribed for a person or another pet.

How it is given

In an emergency, diazepam is often given as an intravenous (IV) bolus. If it is administered as an IV bolus, the dose can be repeated up to 3 times at intervals of 5 to 10 minutes [1]. If seizures continue after the second or third bolus, a CRI of diazepam may be more effective, and a maintenance anticonvulsant such as IV phenobarbital should be started as a preventative [1].

When IV access is not quickly available, veterinarians use other routes. Benzodiazepines are the recommended first-line treatment for canine seizure emergencies, and non-parenteral routes are essential when intravenous access is unavailable [2]. Rectal diazepam has been used this way for years. Clinical trials show that intranasal midazolam controls emergency seizures more reliably than rectal diazepam [2]. Intranasal midazolam appears to be safe and effective for achieving seizure control in canine patients, both in terms of efficacy and speed of onset, and is a suitable first-line treatment option for status epilepticus, especially when intravenous access is not rapidly available [3].

Some dogs are sent home with a benzodiazepine for at-home seizure clusters, but this is a decision your veterinarian makes case by case. If your dog is prescribed an at-home rescue medication, ask for a written plan that states exactly when to use it and when to go to the hospital.

Missed doses

Diazepam is usually given in a hospital or as a rescue medication during a seizure, so a traditional daily missed-dose schedule often does not apply. If your dog is on a scheduled regimen and you miss a dose, call your veterinarian for instructions. Do not double up to make up for a missed dose.

Diazepam for Dogs Side Effects

Most side effects are predictable and tied to the drug's calming action. The table below covers what owners most often see.

Side effect	How common or serious	What to do
Sedation and lethargy	Common. Expected after a seizure dose. Usually mild to moderate [1].	Let your dog rest in a quiet, safe space. Watch breathing and alertness.
Ataxia (wobbliness, unsteady walking)	Common. Related to sedation and muscle relaxation [1].	Block stairs, keep your dog on the floor or a low bed, and assist with a sling if needed.
Paradoxical excitation (excessive excitement, anxiety, or aggression)	Uncommon but well described with benzodiazepines [1].	Stop handling your dog, keep children and other pets away, and call your veterinarian.
Drowsiness after intranasal or rectal benzodiazepine	Mild and reported in clinical use [3].	Monitor at home and report anything that seems excessive.
Serious breathing or cardiovascular problems	Rare at standard veterinary doses, more likely with overdose or when combined with other sedatives.	Treat as an emergency. Call your veterinarian or poison control right away.

Paradoxical excitation is the reaction owners find most alarming because it is the opposite of what they expect. Some animals experience paradoxical excitation, which includes excessive excitement, anxiety, or aggression [1]. If your dog becomes agitated, paces, vocalizes, or snaps after diazepam, do not try to comfort or restrain them. Give them space and call your veterinarian.

If your dog is on other seizure medications, side effects can overlap. Our article on What Are the Side Effects of Seizure Medication in Dogs? covers the broader picture, and What to Expect When Your Dog Starts Seizure Medication: Side Effects and Adjustments explains what the first weeks on a maintenance drug can look like.

Diazepam Sedation in Dogs: What Owners Should Expect

Diazepam sedation in dogs is the most common reason owners call after an emergency visit. Your dog may be sleepy, quiet, and unsteady for a while after a seizure dose. This is expected and usually improves as the drug wears off.

A few practical steps help:

Keep your dog in a quiet, dim room away from stairs and furniture they could fall from.
Offer water but do not force food right away.
Take your dog out to urinate on a leash so they do not wander or stumble.
Do not leave a sedated dog unsupervised around children, other pets, or open doors.
Note the time of the dose and how long the sedation lasts, since this helps your veterinarian plan future treatment.

Sedation that deepens instead of lifting, or a dog who cannot be roused, is not normal and needs veterinary attention.

Diazepam for Dogs Seizures: Where It Fits in a Treatment Plan

Diazepam is the first step, not the whole plan. It stops the seizure in progress. It does not prevent the next one. That is why veterinarians pair it with a maintenance anticonvulsant.

Seizures occurring in dogs with a history of status epilepticus or cluster seizures should each be treated aggressively to avoid a snowball effect [1]. In other words, every seizure in a dog with that history matters, and letting one run its course can make the next one worse.

Long-term seizure control usually involves daily medication. Options include phenobarbital and levetiracetam, and some dogs need more than one drug. Levetiracetam is commonly used as an adjunctive antiseizure medication in dogs because of its favorable pharmacokinetic profile and limited hepatic metabolism, though it is predominantly eliminated through renal excretion [4]. If your dog has refractory epilepsy, your veterinarian may discuss other add-on options. Cannabidiol has gained attention as a potential adjunctive therapy for conditions including epilepsy, and recent studies suggest it may reduce seizure frequency in refractory epilepsy, although results remain variable [5]. A pilot study of dogs with refractory epilepsy found a significant overall reduction in seizure frequency when cannabidiol was added to existing medications [6]. These are decisions for your veterinarian, not something to start on your own.

If your dog has repeated seizures, our guide on What To Do When Dog Gets Seizures covers the steps to take while you are getting help.

Diazepam Long Term in Dogs: Is It Used?

Diazepam long term in dogs is uncommon for seizure control. The drug's short duration of action makes it a poor fit for preventing seizures around the clock. Tolerance can also develop with repeated use, meaning the same dose does less over time.

Long-term daily benzodiazepine use in dogs is more often considered for behavior problems, and even then it is usually part of a broader plan that includes behavior modification and other medications. If your dog has been on diazepam for weeks or months, do not stop it suddenly on your own. Abrupt withdrawal can trigger rebound anxiety or seizures. Your veterinarian will taper the dose safely.

Who Should Not Take Diazepam and What Interacts With It

Dogs with certain health conditions may not be good candidates for diazepam. Your veterinarian will review your dog's history before prescribing it, especially for:

Liver disease, since benzodiazepines are processed by the liver.
Severe breathing problems or airway disease.
Glaucoma or other eye conditions where the drug's effects could be a concern.
Myasthenia gravis or other muscle weakness conditions.
Pregnancy or nursing.

Drug interactions matter too. Diazepam adds to the sedative effect of other drugs that calm the nervous system, including opioids, other benzodiazepines, and some anesthetics. Combining them can cause deeper sedation and, in some cases, breathing problems. Tell your veterinarian about every medication, supplement, and over-the-counter product your dog takes, including anything given for anxiety or pain. If your dog takes gabapentin for pain or anxiety, our article on What Are the Side Effects of Gabapentin for Dogs? explains how that drug behaves in dogs.

Overdose and When to Call a Veterinarian or Poison Control

An overdose of diazepam can cause profound sedation, loss of coordination, weakness, and slowed breathing. Because diazepam is a controlled medication, accidental ingestion of human tablets is a real risk in homes where it is prescribed.

If you think your dog ate diazepam or received too much, call for help immediately. Have the bottle with you so you can read the strength and the number of tablets or milliliters involved.

ASPCA Animal Poison Control Center: (888) 426-4435
Pet Poison Helpline: (855) 764-7661

Do not wait for symptoms to appear. Do not try to make your dog vomit unless a veterinary professional tells you to.

Limitations and When to Contact a Veterinarian

This article covers general information, not your dog's specific case. Individual cases need a veterinarian who can examine your dog, review the history, and adjust treatment.

Contact your veterinarian the same day if:

Your dog is more sedated than expected, or the sedation is not lifting.
Your dog is wobbly enough that they cannot walk without help.
Your dog shows paradoxical excitation, such as unusual agitation, anxiety, or aggression [1].
Your dog vomits, refuses water, or seems painful.
You missed a dose of a scheduled medication.

Go to an emergency clinic now if:

A seizure lasts more than a few minutes or your dog has more than one seizure without fully recovering.
Your dog has trouble breathing, has pale or blue gums, or cannot be woken.
Your dog collapses or has a seizure after a possible overdose.
Your dog's temperature feels very high or very low.

Schedule a routine visit if:

Seizures are becoming more frequent or more severe.
You are seeing side effects that concern you even though your dog seems stable.
You want to review whether diazepam is still the right rescue medication for your dog.

Frequently Asked Questions

How long does diazepam sedation last in dogs?

Sedation usually eases as the drug clears from your dog's system, and the exact timing depends on the dose, the route, and your dog's health. Some dogs are back to normal within a few hours, while others stay sleepy longer. If the sedation is deepening or your dog cannot be roused, call your veterinarian.

Can I give my dog my own diazepam?

No. Never give your dog medication prescribed for a person or another pet. The dose depends on your dog's weight and health, and human tablets come in strengths that can easily be too much for a dog. Only use diazepam that your veterinarian has prescribed for your dog.

Is diazepam safe for long-term use in dogs?

It is not a common long-term choice for seizure control because it does not last long enough to prevent seizures around the clock. Long-term use is sometimes considered for behavior problems as part of a wider plan. Never stop a long-term benzodiazepine suddenly, since withdrawal can trigger serious problems.

What should I do if my dog gets excited instead of sleepy on diazepam?

Give your dog space and call your veterinarian. Paradoxical excitation means the drug caused excessive excitement, anxiety, or aggression instead of calm [1]. Do not restrain or comfort your dog during this reaction, since handling can make it worse.

Can diazepam be used at home for seizure clusters?

Sometimes, but only with a written plan from your veterinarian. Benzodiazepines are the recommended first-line treatment for canine seizure emergencies, and non-parenteral routes are used when intravenous access is unavailable [2]. Your veterinarian will decide whether an at-home rescue medication is appropriate and which one to use.

References

Anticonvulsants for Emergency Treatment of Seizures in Dogs and Cats - Pharmacology. Merck Veterinary Manual.
Quantitative electroencephalographic comparison of intranasal midazolam, intranasal saline, and intrarectal diazepam in healthy dogs: A two-session, fixed-order pilot study. Veterinary journal (London, England : 1997), 2026.
Intranasal midazolam as an alternative to rectal diazepam for management of canine status epilepticus. Veterinary evidence, 2024.
Short-Term Renal Effects of Add-On Levetiracetam in Client-Owned Dogs with Idiopathic Epilepsy Receiving Phenobarbital: A Four-Week Prospective Study. Veterinary sciences, 2026.
Cannabidiol in small animal practice: current evidence, clinical applications and practical recommendations for dogs and cats. The Journal of small animal practice, 2026.
An Exploratory Study of Cannabidiol as an Adjunctive Treatment for Refractory Epilepsy in Dogs. Animals : an open access journal from MDPI, 2025.