Epiphen for dogs


Tablets / liquid

Active ingredient




What is Epiphen?

Epiphen is a brand name for the anti-seizure drug called phenobarbital. It comes as a tablet or a liquid solution, and is commonly used to treat epilepsy in dogs. Only your veterinarian will be able to provide your pet with Epiphen.

What does Epiphen do for dogs?

Epiphen contains the anti-seizure drug phenobarbital, which is mainly used in dogs to treat seizures caused by epilepsy, toxins, or brain tumours. It is important to control seizures because they can cause long-lasting damage to your pet’s brain.

Seizures are caused by over-active nerves in the brain. Phenobarbital works by calming these nerves down, therefore preventing seizures from happening. When Epiphen binds to GABA-A, it locks the chloride ion channels ‘open’, allowing lots of ions in. This means the cell has to work harder to fire, therefore reducing firing rate and calming the nerves down.

What is Epiphen used for?

Epiphen is mainly given to dogs to treat epilepsy and other causes of seizures. Your vet may give your pet Epiphen for another reason.

Here are the other reasons why Epiphen is recommended for dogs:

  • Epilepsy – this is the most common reason.
  • Other conditions that cause seizures e.g. toxins and brain tumours.
  • Behavioural disorders – this is less common.

Sometimes, Epiphen is given ‘off-license’ or ‘off-label’ via the presribing cascade. This allows vets to use different drugs based on experience when there are no licensed drugs available.

Remember, Epiphen should always be given under veterinary guidance, ensure to consult your vet so that you can do what’s best for your pet.

What are the side effects of Epiphen in dogs?

Whilst most pets tolerate Epiphen without any serious issues, it can have side effects just like all other medications. Most of the side effects of Epiphen are usually mild and only last for a short time. However, some dogs may experience mild side effects for the entire duration of treatment.

The common side effects of Epiphen that you should be aware of include:

  • Loss of coordination – this affects less than 1 in 1000 dogs on Epiphen. It is most likely to happen at the start of Epiphen treatment, but may continue.
  • Sleepiness – this is also most likely to happen at the start of Epiphen treatment, but it may continue in some dogs.
  • Over-excitedness or restlessness – there is no major concern with this side effect so you can continue to give your dog Epiphen if they are restless on this drug.
  • Increased appetite, drinking and urinating – these usually disappear without having to stop Epiphen, and occur in less than 1 in 1000 animals
  • Liver damage – this side effect is very rare (current data suggests less than 1 in 10,000 treated animals) and is usually seen with very high doses of Epiphen. Your veterinarian will monitor your dog’s liver when on this medication to catch damage early.
  • Changes to the blood – these include decreased red blood cells and decreased white blood cells (cells responsible for fighting infection). This happens in less than 1 in 10,000 treated animals.
  • Aggression – this is seen in less than 1 in 10,000 treated animals

Remember, the benefits of using Epiphen usually outweigh these risks, especially in pets with serious health conditions. However, if you do notice any of these side effects or are worried about a change in your pet’s well-being, get in touch with your veterinarian for more advice. They will be able to provide you with guidance and adjust the treatment plan if necessary. This will help to ensure your pet’s safety and put your mind at ease. 

Which pets is Epiphen not suitable for?

Whilst Epiphen is suitable for most pets, there are a few situations where Epiphen should be avoided, and alternatives should be discussed with your vet.

  • Epiphen is not suitable for dogs with reduced liver function.
  • Epiphen is not suitable for pregnant or lactating dogs.
  • Epiphen is not suitable for dogs that are allergic to any of the ingredients in the product.
  • Epiphen is not suitable for dogs with serious kidney, heart, or respiratory disease.
  • Epiphen is not suitable for dogs with anaemia or hypovolaemia. Hypovolaemia means low blood volume, which could be due to blood loss or dehydration.

How to give Epiphen safely:

  1. Follow vet instructions: Always use Epiphen exactly as your vet has prescribed. This includes the right dose and frequency (usually twice daily, so every 12 hours). The full effect of Epiphen will not appear for 2 weeks so please be patient and never adjust the dose on your own, even if your dog seems to be feeling better or worse. If you aren’t sure of the dose prescribed, please call your vet to confirm.
  2. Give with or just after food: It is recommended that Epiphen tablets are given at the same time every day, during mealtime. You can either put it on your pet’s food or directly into their mouth after they’ve eaten.
  3. Giving the medication: Epiphen can be given directly into your dog’s mouth or can be hidden in a piece of food such as a strawberry or some cream cheese. If you are struggling to give your dog their tablets, it may be worth considering a different formulation of phenobarbital or a different drug.
  4. Do not handle if pregnant or breastfeeding: Epiphen has toxic effects on the foetus and neurological development. It can also transfer to breastmilk. Women who may be pregnant or who are breastfeeding should not handle this medication.
  5. Check with your vet if giving anything else: Your vet should be aware of other drugs your pet is on, but it’s always worth double-checking in case there’s been a miscommunication somewhere. Epiphen cannot be given with some other drugs, including antibiotics, steroids, and other anti-seizure drugs. If your dog is on supplements or non-prescription treatments, even if they are natural or herbal, you should also tell your vet when they prescribe Epiphen, as they may not be suitable to be given together.
  6. Storage and Handling: Store Epiphen according to the instructions on the label, usually in a cool and dry place. Make sure it’s out of reach of children and other pets, as accidental ingestion can prove fatal. You should wear gloves whilst handling this drug and wash your hands after use.
  7. Report any accidental overdose to your vet immediately: If you have mistakenly given too much Epiphen to your dog, report it to your vet as soon as you realise the error. They may recommend testing your pet’s blood and monitoring.
  8. Accidental ingestion: If you or your child accidentally eats Epiphen, contact your doctor immediately and show them the packet. Epiphen can be fatal.

What monitoring do dogs on Epiphen need?

  • High monitoring need


    Dogs on Epiphen need to be closely monitored. This reduces in frequency once they’re stable.

Dogs on Epiphen will need to be monitored closely, especially when they first start the medication. You’ll need to record the number and length of any seizures at home, and your vet will want to test your dog’s blood for the amount of phenobarbital as well as their liver values. Once dogs are on a stable dose that seems to be working with no side effects, the frequency of monitoring will decrease. However, they’ll still need blood tests, usually every 3-6 months.

Epiphen FAQs

What does Epiphen do to dogs?

Epiphen contains the anti-seizure drug phenobarbital and is used to treat epilepsy in dogs. Epiphen reduces the number and severity of your pet’s seizures by calming the over-excited neurons in your dog’s brain. Therefore, Epiphen helps to control your dog’s seizures and epilepsy to make them feel better.

Epiphen may have some undesirable side effects on your dog, including aggression and drowsiness. If you are concerned about any of these side effects, get in touch with your vet for what to do next.

Is phenobarbital the same as Epiphen?

Yes, phenobarbital and Epiphen are the same thing. Epiphen is a brand name for the anti-seizure drug phenobarbital, marketed for dogs. There are several other brand names of dog drugs containing phenobarbital, such as Soliphen and Epityl. 

What are the side effects of Epiphen tablets?

The side effects of Epiphen tablets include drowsiness, increased drinking and urinating, increased appetite, lack of coordination, liver damage with long-term use, aggression, and changes to the blood. The severity of these side effects will vary between dogs. Always follow your vet’s guidance to reduce any chance of your pet experiencing these side effects.

What is the best epilepsy medication for dogs?

Drugs containing phenobarbital, such as Epiphen, are often the medication of choice for dogs with epilepsy, but they won’t work for all dogs. Based on your pet’s response to treatment, and the amount of phenobarbital in their blood, your vet may increase or decrease the dose of phenobarbital.

If your pet is experiencing severe side effects to phenobarbital, they may suggest trying a different epilepsy medication, such as potassium bromide (Libromide) or imepitoin (Pexion).

How often do dogs need Epiphen?

Epiphen is usually prescribed for twice daily use, so you’ll need to give your dog their dose every 12 hours. However, your vet may prescribe a different frequency for your pet, so always read the label and call them if you aren’t sure.

How long can Epiphen be used for?

As long as there are no side effects, Epiphen can be used for life. If the Epiphen is being used to control seizures that are temporary in nature (for instance, due to toxins), your vet may try to wean your dog off Epiphen. In most cases, Epiphen is used for epilepsy or seizures related to brain tumours, which are lifelong conditions, so it’s normally used for life.

What are the alternatives to Epiphen?

If Epiphen doesn’t appear to be working, let your veterinarian know as they may be able to increase the dose or add in additional medications. Do not do this yourself, the vet will know how much to increase the dose, in the safest way.

If you are struggling to get your dog to take their Epiphen tablets, there are some alternative formulations you could try that still contain phenobarbital.

Alternative phenobarbital formulations include:

  • Epiphen Oral drops- These may be easier to administer and could be worth a try in smaller animals.
  • Epityl Flavoured tablets – These tasty tablets may be more appealing to your pet.

If you find that Epiphen isn’t working well after 2 weeks of treatment, there are many other anti-seizure drugs available. These alternatives may also be useful if your dog is experiencing side effects or is allergic to Epiphen.

Here are some of the alternative anti-seizure drugs: 

  • Potassium bromide e.g. Libromide – available as a tablet.
  • Levetiracetam – available as a tablet, injection, or liquid.
  • Zonisamide – available as a tablet but can be made into a liquid suspension.
  • Imepitoin e.g. Pexion – available as a tablet

It is important to remember that you will not be able to buy any anti-seizure medication for your pet over a non-veterinary counter! You will have to go back to your vet to discuss the other options, where you can both decide what is the next best thing for your pet to keep them happy and comfortable.

Epiphen Datasheet

All drugs have a manufacturer’s datasheet, which gives information about the drug’s use and possible side effects. There is usually one in your Epiphen box, but if you have lost it you can click on the button below to be taken on an online version.

Courses related to Epiphen

We don’t currently have any courses about seizures in dogs, but check back soon!

Please note that the information contained herein is provided for informational purposes only. Although it has been written by a vet, we cannot consider the individual nature of your pet’s problems so it does not constitute veterinary advice. If you have questions about your pet’s medication or their health you should contact a vet, who will be able to help.