Diazepam

Diazepam is an active substance from the benzodiazepine group. It dampens the nervous system, relieves anxiety, relaxes the muscles and stops seizures. In dogs, the vet uses it mainly in emergencies for seizures, less often for sedation or severe anxiety. Given alone, diazepam often calms a healthy dog only unreliably.

Important: If your dog has cluster seizures, the vet may give you a diazepam product for home use that is given into the rectum during a seizure. Use it only as the vet has shown and instructed you, and never give a medicine from your own medicine cabinet. Always call the veterinary practice afterwards, even if the seizure has stopped. If a seizure lasts longer than a few minutes, if several seizures follow in quick succession, or if your dog does not fully wake up between seizures, go to the animal hospital straight away.

According to CliniPharm (University of Zurich, accessed October 2026), no veterinary medicine containing diazepam is currently authorised in Switzerland. In Germany and Austria, veterinary medicines containing diazepam are authorised for dogs and cats, as a solution for injection into a vein. If no authorised veterinary medicine is available, the vet may switch to another medicine in individual cases. A fixed order applies to this, and a product for humans only becomes an option after other veterinary medicines. This is called off-label use (known as cascade use in Europe), and it is reserved for vets. In Switzerland, the veterinary practice can also import a veterinary medicine authorised abroad under certain conditions.

When is diazepam used in dogs?

Seizures: In a seizure emergency, diazepam is considered the drug of choice to stop an ongoing seizure or a cluster of seizures. It is not suitable for the long-term treatment of epilepsy in dogs: the body breaks the substance down quickly and gets used to it within a short time.

Poisonings and muscle spasms: for example in poisonings that cause seizures, in tetanus or with painful muscle tension.

Sedation before examinations: Because diazepam alone often does not calm a dog reliably and can even make some dogs more excited, the vet usually combines it with other medicines.

Anxiety: for example separation anxiety or fear of thunderstorms and loud bangs, then together with behaviour therapy (more on this below).

Appetite: Diazepam can stimulate appetite, although much more effectively in cats than in dogs.

Authorisation and off-label use

The veterinary medicines authorised in Germany and Austria are solutions for injection for use in the veterinary practice. Whether your dog receives a veterinary medicine or another product for home use, for example one for humans, is decided by the vet.

How does diazepam work?

Diazepam enhances an inhibitory messenger substance in the brain. This makes nerve cells less excitable: seizures can stop, muscles relax, anxiety decreases. In dogs the effect is short, because the body breaks the substance down quickly. Diazepam does not relieve pain.

Risks and side effects

• Tiredness and unsteadiness: Drowsiness, a wobbly gait and poorer coordination are possible.
• Paradoxical excitement: Instead of calming down, the dog becomes restless, overexcited or even aggressive. This happens in dogs time and again, especially in small breeds, dachshunds and hunting dogs after an injection. Dogs that react aggressively out of fear can become even more aggressive because of the loss of inhibition.
• Memory and learning: Diazepam impairs learning and memory. This can interfere with training.
• Tolerance: In dogs, the effect already wears off after a few days because the body gets used to the substance.
• Dependence: After longer use, the body can become dependent.
• Circulation: If diazepam is injected into a vein too quickly, blood pressure and heart rate can drop. This is why the vet injects it slowly.
• Overdose: It leads to heavy sedation up to unconsciousness. The veterinary practice has an antidote.

Do not stop abruptly: If your dog has been given diazepam for a longer period, it must not be stopped suddenly. Otherwise anxiety, listlessness, trembling, seizures and fever can occur. The vet decides how to taper the dose off slowly.

Only for your dog: In cats, diazepam given by mouth can cause life-threatening liver damage. So never give a product intended for your dog to your cat or to any other animal.

Watch out for: If your dog becomes very restless or aggressive after a dose, can hardly be woken, breathes noticeably shallowly or has another seizure, contact the veterinary practice straight away.

When must diazepam not be given?

• with liver disease only with caution, because the substance then acts much longer; the same applies to kidney disease and very old dogs
• in aggressive dogs only with great caution or not at all; with fear-related aggression too, only under close observation, because it can increase
• during pregnancy only after careful consideration, especially in the first third; during nursing the substance passes into the milk and can sedate the puppies
• in poisoning with organophosphates, for example from certain insecticides
• in working dogs in training only with care, because learning suffers

Interactions and what the vet needs to know

Other sedating medicines enhance the effect of diazepam, for example sedatives, barbiturates, opioids and anaesthetics. Certain stomach, antifungal and heart medicines, some antibiotics and the antidepressant fluoxetine can also increase sedation. Phenobarbital, a long-term epilepsy medicine, lowers the diazepam level in the blood; given together, they can put more strain on breathing and circulation. Medicines against stomach acid delay the absorption of tablets.

So tell the vet which other medicines your dog receives, whether he has liver or kidney problems, whether he has ever reacted with overexcitement or aggression to a sedative, and whether your bitch is pregnant or nursing.

Forms & use in dogs

Injection: The vet gives diazepam slowly into a vein. It is not injected into the muscle or under the skin, because this is painful, can excite the dog and the substance is absorbed unevenly.

Into the rectum: This form is absorbed well and is suitable for a seizure emergency at home, if the vet has prescribed it and shown you how to use it.

Into the nose: Diazepam is also absorbed through the nasal lining. The vet decides whether this form suits your dog.

Tablets: They are not suitable as a long-term medicine for dogs, because the liver breaks down a large part of the substance straight after absorption and the effect wears off quickly.

How much, how often and for how long your dog receives diazepam is set by the vet. Give it only as prescribed.

Diazepam for fireworks or New Year’s Eve?

For fear of loud bangs and thunderstorms, diazepam can dampen anxiety in the short term. However, its use in dogs has hardly been studied: there are only a few veterinary studies, and much of the evidence comes from human medicine. There are also drawbacks: some dogs lose their inhibitions or become aggressive, and your dog may process what he experiences under diazepam less well. It is best to discuss with the vet well before the turn of the year whether diazepam or another medicine is an option for your dog.

Combination with behaviour therapy

For anxiety problems, diazepam does not replace behaviour therapy. It can defuse an acute situation, but the actual learning happens in training. Because diazepam slows learning and can lead to tolerance and dependence with longer use, it is not suitable as a long-term solution. Plan the treatment with the vet and, if needed, with a professional trained in veterinary behavioural medicine.

Conclusion: diazepam is an emergency medicine with limits

In dogs, diazepam has a firm place in seizure emergencies. As a sedative or anti-anxiety medicine, it works unreliably and briefly, can cause paradoxical excitement and can interfere with learning. Give it only as the vet has instructed, do not stop it on your own, and contact the practice after every emergency use.