phenobarbital
Phenobarbital is an anticonvulsant that vets prescribe off-label to treat seizures and epilepsy in dogs and in cats. It’s usually given twice a day, but the specific dosage depends on your pet’s weight. Phenobarbital commonly comes as tablets. But it can also be made into a liquid, oral paste, chewable treat, or topical gel to make it easier for your pet to take. The injectable form is mainly used by vets. Common side effects are sleepiness, hunger, thirst, and more frequent urination. Phenobarbital is a controlled substance that can be habit-forming for pets with long-term use.
What is Phenobarbital for pets?
What is Phenobarbital for pets used for?
How Phenobarbital for pets works
Phenobarbital is a type of anticonvulsant called a barbiturate. It works by calming down the electrical activity in your pet’s brain. This helps prevent seizures from happening.
Drug facts
Risks and warnings for Phenobarbital for pets
Phenobarbital can cause some serious health issues. This risk might be even higher for certain pets. If this worries you, talk to your veterinarian about other options.
Liver damage
- Risk factors: Dogs | High doses of phenobarbital | Pets taking phenobarbital for a long time | Pets taking other medications that can harm the liver
Although rare, phenobarbital can damage the liver, which can sometimes be life-threatening. This happens if the levels in your pet’s body get too high. It can also happen if your pet takes it for a long time or is taking other medications that can harm the liver. Studies suggest that liver damage might happen more often in dogs than in cats. Because of this risk, phenobarbital isn’t recommended for pets with liver problems.
To lower the risk of liver damage, the vet will collect blood samples from your pet at least every 6 months. These blood samples help the vet check how safe the medication is for your pet’s liver.
Watch for signs like a swollen belly, vomiting, diarrhea, loss of appetite, and yellowing of the eyes or gums. Call a vet right away if you notice these symptoms in your pet. They could be signs of liver damage.
Low blood cell counts
It’s not common, but phenobarbital can sometimes cause low blood cell counts in dogs. It can also happen in cats. This can mean that your pet’s red blood cell counts, white blood cell counts, or platelet levels are low. Some cases can be mild, but others can also be more serious and life-threatening.
Your vet will draw your pet’s blood during check-ups to monitor blood cell counts. This helps make sure that phenobarbital is safe for your pet. Let your vet know if your pet has signs of low blood cell counts, like low energy, a loss of appetite, vomiting, or fever.
Skin reaction
- Risk factors: Taking phenobarbital for a long time | Small-breed dogs | Age greater than 10 years | Liver problems | Diabetes | Hypothyroidism
Pets taking phenobarbital are at risk for a rare but very serious skin reaction called superficial necrolytic dermatitis (SND). This might be more likely to happen in dogs that take the medication for a long time. The risk might also be higher for dogs with liver problems and older small-breed dogs.
SND usually causes painful, itchy sores or wounds on the feet. These sores can also spread to the mouth, ears, and genitals. It can also cause trouble walking, sleepiness, loss of appetite, more thirst, and frequent urination. Tell your vet if your pet has any signs of SND during treatment.
Drug interactions
Phenobarbital can interact with many other medications. They can include other anticonvulsants, certain antibiotics, and antihistamines like diphenhydramine (Benadryl), among others. For dogs, another medication that can interact with phenobarbital is carprofen (Rimadyl). Drug interactions can be harmful to your pet.
To keep your pet safe, talk to your vet before giving your pet any new or over-the-counter medications. They can check if the medication is safe to with phenobarbital. They can also explain the risks and benefits of taking them together. Your vet can guide you on the best way to manage your pet’s medications.
Slowed breathing
- Risk factors: Lung problems | Taking other medications that slow breathing down
Phenobarbital can cause slow, shallow, or difficulty breathing in dogs and cats. This can be dangerous for pets that already have breathing problems or take other sedatives. Talk to your vet to make sure phenobarbital is safe for your pet. Get immediate care if you notice your pet is having trouble breathing or breathing very slowly.
Withdrawal seizures
- Risk factors: Stopping phenobarbital too suddenly
If you suddenly lower the dose or stop giving phenobarbital, your pet can have seizures again, especially if they’ve been taking the medication for a long time. Talk to your vet before you lower the dose or stop giving phenobarbital to your pet to make sure it’s safe. The vet might slowly lower the dose over time to see how your pet reacts to the change. Be aware of when you need to get refills so your pet doesn’t run out of medication.
Side effects of Phenobarbital for pets
The following side effects might get better over time as your pet gets used to the medication. Let your veterinarian know immediately if your pet continues to experience these symptoms or if they worsen over time.
Common Side Effects
- Sleepiness
- Low energy
- Agitation
- Anxiety, nervousness, or restlessness (e.g., pacing, panting, whining)
- Very excited
- Eating more
- Drinking more water than usual
- Urinating more often than usual
Less Common Side Effects
- Trouble walking
- Itchy face (cats only)
Phenobarbital serious side effects
Contact your veterinarian immediately if your pet experiences any of the following.
- Liver damage: yellowing in the eyes or gums (jaundice), severe vomiting, loss of appetite
- Low blood cell counts: bleeding, infection, pale or white gums
- Phenobarbital levels that are too high: extreme sleepiness, slow or shallow breathing, problems walking or stumbling, weakness, low body temperature, unconsciousness
- Slow or labored breathing
- Skin reaction: painful, itchy sores or wounds on the skin
The following Phenobarbital side effects have also been reported
Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor immediately if any of the following side effects occur:
Rare
Confusion (especially in the elderly)
dizziness, lightheadedness that continues, or fainting
skin rash or hives
Incidence not known
difficulty with swallowing
fast irregular, pounding, or racing heartbeat or pulse
hives or welts
hoarseness
irritation
itching skin
joint pain, stiffness, or swelling
puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
redness of the skin
shortness of breath
skin rash
tightness in the chest
trouble with breathing
Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
Less common or rare
Bloated feeling
blurred vision
difficult urination
difficulty with swallowing
drowsiness
false sense of well-being
headache
increased sensitivity of eyes to light
loss of memory
nausea or vomiting
redness or other signs of irritation at the place of injection
trouble with sleeping
unusual tiredness or weakness
Incidence not known
Decreased interest in sexual intercourse
inability to have or keep an erection
loss in sexual ability, desire, drive, or performance
loss of taste
For patients using scopolamine:
After you stop using scopolamine, your body may need time to adjust. The length of time this takes depends on the amount of scopolamine you were using and how long you used it. During this period of time check with your doctor if you notice any of the following side effects:
irritability
nightmares
pupil of one eye is larger (patch only)
sensitivity of eyes to light (patch only)
trouble in sleeping
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
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Pros and cons of Phenobarbital for pets
Pros
- First-choice treatment for long-term seizure control in dogs and in cats
- Has been used the longest in veterinary practice for epilepsy in dogs
- Comes as tablets and can also be made into a liquid or other forms if needed
Cons
- Must have your pet’s blood drawn at least every 6 months to check phenobarbital levels, blood cell counts, and organ function
- Is a controlled substance so there are restrictions on filling a prescription
- Might have to give to your pet for the rest of their life
Pharmacist tips for Phenobarbital for pets
- Follow the vet’s instructions to give phenobarbital to your dog or cat safely. Usually, this medication is given twice a day. But your vet might also say that it’s okay to give it once a day if you have trouble getting your pet to take the medication twice a day.
- You can give your pet phenobarbital with or without food. If they vomit or have an upset stomach after taking it on an empty stomach, try giving it with food next time.
- Your pet will need regular blood tests while taking phenobarbital to check the levels of the medication. This helps the vet make sure it’s safe and effective for your pet. For the most accurate results, get the blood drawn in the morning before your pet eats and takes their medication. Tests are done 2 weeks after starting treatment, 2 weeks after dose changes, and at least every 6 months once seizures are controlled. Your vet might adjust the dose based on test results.
- Your pet will need other regular blood tests to check for rarer side effects of phenobarbital. These tests check liver function and blood cell counts. Ask your vet about what the test results mean.
- Talk to your vet if it doesn’t seem like phenobarbital is helping with your pet’s seizures after 2 weeks of treatment. It could mean that the dose needs to be adjusted or that your pet needs a different medication.
- Don’t stop giving your pet phenobarbital suddenly, especially if they’ve taken it for a long time already. Pets can have withdrawal from the medication and seizures can come back. Plan ahead for refills so that your pet doesn’t run out of medication.
- Phenobarbital is a controlled substance. Keep your pet’s medication secured and away from others, including children. Don’t give phenobarbital to others to use. Store it in a locked cabinet or safe at room temperature. Follow local, state, and federal laws to dispose of this medication safely.
Tips for liquid forms of phenobarbital
- Your vet might suggest a special liquid form of phenobarbital that’s made to taste better for your pet. Don’t use the phenobarbital liquid that you can get at regular pharmacies because it has alcohol in it, which can be dangerous for pets.
- This specially-made phenobarbital liquid is usually from a compounding pharmacy. Follow the vet’s or pharmacy’s instructions on how to store it and when to dispose it.
- Don’t measure the liquid medication with household spoons since spoon sizes can vary. Use a dosing cup or oral syringe to measure out the phenobarbital dose for your pet. This helps make sure your pet gets the right dose of medication.
Tips for other compounded forms of phenobarbital
- Compounding pharmacies can make phenobarbital into other forms to make it easier for your pet to take. These include a paste that's put into your pet’s mouth, a chewable treat, and sometimes a topical gel that you rub on the inside of the earflaps.
- Follow your vet’s or pharmacy’s instructions on how to store, give, and dispose of phenobarbital safely and properly.
Common questions about Phenobarbital for pets
Signs of phenobarbital toxicity in dogs include sleepiness, unsteady movement, trouble breathing, low body temperature, loss of reflexes, and unconsciousness. And though rare, phenobarbital can be toxic to your dog’s liver. This can look like loss of appetite and yellowing of the eyes or gums. It’s important that the vet checks your dog’s phenobarbital blood levels to make sure they’re at a safe level. If you think your dog has gotten too much phenobarbital, contact a veterinarian or a pet poison helpline right away.
No, phenobarbital requires a valid prescription from a licensed veterinarian. It needs a prescription because the vet needs to monitor your dog during treatment to make sure it’s safe. Also, phenobarbital is a controlled substance in the United States. This means that there are state laws that can limit access to the medication. Sometimes, these state laws can be stricter than federal laws. Ask a vet if you have more questions about whether your dogs needs phenobarbital and what you need to know about these laws.
You can get phenobarbital tablets for your dog at most pharmacies. But for other forms of phenobarbital your vet might prescribe, like a liquid, paste, or chewable treat, you’ll need to go to a special pharmacy called a compounding pharmacy. These pharmacies can make medication in different forms to help your dog take it more easily. Remember, you’ll need a prescription from a licensed veterinarian for phenobarbital. This is because a vet must make sure the dose is safe for your dog and monitor them for side effects. Ask a vet where to get the right form of phenobarbital that’s prescribed for your dog.
It usually takes about 2 weeks for phenobarbital to reach a steady level in your dog’s body. Your vet will check the phenobarbital levels in your dog’s blood 2 weeks after starting the medication and after dose changes. This makes sure the dose is right since there’s a range that’s generally safe and works well for dogs. It could take a few weeks for phenobarbital to fully control seizures in your dog since it could take time to reach the right dose. But remember that the medication might work differently for each dog to help control seizures. Ask your vet if you have questions about how long it’s taking phenobarbital to work or about your dog’s phenobarbital levels.
Phenobarbital and levetiracetam (Keppra) are anticonvulsants that vets prescribe for seizures in dogs. But they work in different ways to calm brain activity and lower the number of seizures. Phenobarbital is usually given less often throughout the day than levetiracetam (Keppra). But blood tests are often needed to check phenobarbital levels for safety. This isn’t usually required with levetiracetam (Keppra), unless it’s taken with phenobarbital. Ask your vet for more information on comparing these medications.
Yes, your vet might prescribe both levetiracetam (Keppra) and phenobarbital for your dog’s seizures. They work in different ways to help lower how many and how severe the seizures are. It’s very important to follow your vet’s directions when giving these medications. Your dog will also need regular blood tests to make sure that both medications are safe and working well. Ask your vet if you have questions about giving your dog levetiracetam (Keppra) and phenobarbital.
Yes, phenobarbital can make dogs hungry as a side effect. When your dog first starts taking phenobarbital, you might notice that they’re hungrier or eating more than usual. Sometimes, this higher appetite might lead to weight gain. But their appetite should go back to usual within a few weeks. Talk to a vet if you’re concerned about any changes in appetite or weight in your dog.
A side effect that can happen with long-term phenobarbital use in dogs is thirst. This can lead dogs to drink lots of fluids and urinate more. It can also cause changes to your dog’s thyroid lab results, which could be mistaken for hypothyroidism (low thyroid hormone levels). The most serious complication of long-term phenobarbital treatment in dogs is liver toxicity. The medication can raise the liver enzyme levels in your dog, which can be a sign of liver damage. Other signs of liver toxicity include yellowing of the skin, eyes, or gums; swollen belly; and loss of appetite. Talk to your vet if you’re worried about the long-term risks with phenobarbital for your dog.
Signs of phenobarbital toxicity in cats include sleepiness, weakness, trouble walking, changes in breathing, low body temperature, and unconsciousness. This can happen if a cat takes too much phenobarbital or if the medication levels in the body are too high. If you notice these signs in your cat, call a vet or pet poison helpline right away.
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Phenobarbital dosage forms for pets
Ml of elixir| Dosage | Quantity | Price as low as | Price per unit |
|---|---|---|---|
| 20mg/5ml | 120 ml | $12.20 | $0.10 |
Typical dosage for Phenobarbital
The dose will depend on your pet’s weight.
Long-term management of seizures in dogs and cats: The typical starting dose for the oral forms of phenobarbital is 2 mg/kg to 3 mg/kg by mouth twice a day. The vet will adjust the dose based on the phenobarbital levels in your pet’s blood. The dose will also be adjusted based on the number and severity of the seizures.
Phenobarbital is also available as an injection that’s given by a vet for seizures in emergency situations.
Interactions between Phenobarbital and other drugs for pets
Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking any of these medicines, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.
Using medicines in this class with any of the following medicines is not recommended. Your doctor may decide not to treat you with a medication in this class or change some of the other medicines you take.
- Ambenonium
- Bepridil
- Bromopride
- Cisapride
- Dronedarone
- Fluconazole
- Itraconazole
- Ketoconazole
- Mesoridazine
- Nelfinavir
- Pimozide
- Piperaquine
- Posaconazole
- Potassium
- Potassium Chloride
- Saquinavir
- Sparfloxacin
- Terfenadine
- Thioridazine
- Ziprasidone
Using medicines in this class with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
- Aclidinium
- Alfentanil
- Alfuzosin
- Alprazolam
- Amifampridine
- Amiodarone
- Amisulpride
- Amitriptyline
- Amobarbital
- Amoxapine
- Anagrelide
- Anileridine
- Apomorphine
- Aripiprazole
- Aripiprazole Lauroxil
- Arsenic Trioxide
- Asenapine
- Astemizole
- Atropine
- Azithromycin
- Baclofen
- Bedaquiline
- Belladonna
- Benzhydrocodone
- Benztropine
- Biperiden
- Bromazepam
- Brompheniramine
- Buprenorphine
- Bupropion
- Buserelin
- Buspirone
- Butabarbital
- Butorphanol
- Calcium Oxybate
- Cannabidiol
- Carbinoxamine
- Carisoprodol
- Ceritinib
- Cetirizine
- Chloral Hydrate
- Chlordiazepoxide
- Chloroquine
- Chlorpheniramine
- Chlorpromazine
- Chlorzoxazone
- Ciprofloxacin
- Citalopram
- Clarithromycin
- Clemastine
- Clidinium
- Clobazam
- Clofazimine
- Clomipramine
- Clonazepam
- Clorazepate
- Clozapine
- Codeine
- Conivaptan
- Crizotinib
- Cyclobenzaprine
- Cyclopentolate
- Cyclosporine
- Cyproheptadine
- Dabrafenib
- Darifenacin
- Darolutamide
- Dasatinib
- Degarelix
- Delamanid
- Desipramine
- Deslorelin
- Deutetrabenazine
- Dexmedetomidine
- Diacetylmorphine
- Diazepam
- Dicyclomine
- Difenoxin
- Digoxin
- Dihydrocodeine
- Dimenhydrinate
- Diphenhydramine
- Diphenoxylate
- Disopyramide
- Dofetilide
- Dolasetron
- Domperidone
- Donepezil
- Doxepin
- Doxylamine
- Droperidol
- Duvelisib
- Ebastine
- Efavirenz
- Eltrombopag
- Enasidenib
- Encorafenib
- Entrectinib
- Eribulin
- Erythromycin
- Escitalopram
- Esketamine
- Estazolam
- Eszopiclone
- Ethchlorvynol
- Ethylmorphine
- Famotidine
- Felbamate
- Fentanyl
- Fesoterodine
- Fingolimod
- Flavoxate
- Flecainide
- Flibanserin
- Fluconazole
- Flunitrazepam
- Fluoxetine
- Fluphenazine
- Flurazepam
- Formoterol
- Foscarnet
- Fosnetupitant
- Fosphenytoin
- Fospropofol
- Fostemsavir
- Gabapentin
- Gabapentin Enacarbil
- Galantamine
- Gatifloxacin
- Gemfibrozil
- Gemifloxacin
- Givosiran
- Glasdegib
- Glucagon
- Glycopyrrolate
- Glycopyrronium Tosylate
- Gonadorelin
- Goserelin
- Granisetron
- Halazepam
- Halofantrine
- Haloperidol
- Histrelin
- Homatropine
- Hydrocodone
- Hydromorphone
- Hydroquinidine
- Hydroxychloroquine
- Hydroxyzine
- Hyoscyamine
- Ibutilide
- Idelalisib
- Iloperidone
- Imipramine
- Inotuzumab Ozogamicin
- Ipratropium
- Itraconazole
- Ivabradine
- Ivosidenib
- Ketamine
- Ketazolam
- Ketobemidone
- Ketoconazole
- Lapatinib
- Larotrectinib
- Lefamulin
- Leflunomide
- Lemborexant
- Lenvatinib
- Levocetirizine
- Levofloxacin
- Levorphanol
- Lofexidine
- Lopinavir
- Lorazepam
- Lorlatinib
- Loxapine
- Lumacaftor
- Lumefantrine
- Macimorelin
- Magnesium Oxybate
- Meclizine
- Mefloquine
- Memantine
- Mepenzolate
- Meperidine
- Mephobarbital
- Meprobamate
- Meptazinol
- Metaxalone
- Methacholine
- Methadone
- Methocarbamol
- Methohexital
- Methotrimeprazine
- Metoclopramide
- Metronidazole
- Midazolam
- Mifepristone
- Mirtazapine
- Mizolastine
- Moricizine
- Morphine
- Morphine Sulfate Liposome
- Moxifloxacin
- Nafarelin
- Nalbuphine
- Netupitant
- Nicomorphine
- Nilotinib
- Nitrazepam
- Norfloxacin
- Nortriptyline
- Octreotide
- Ofloxacin
- Olanzapine
- Ondansetron
- Opium
- Opium Alkaloids
- Orphenadrine
- Osilodrostat
- Osimertinib
- Oxaliplatin
- Oxazepam
- Oxitropium Bromide
- Oxybutynin
- Oxycodone
- Oxymorphone
- Ozanimod
- Paliperidone
- Panobinostat
- Papaveretum
- Papaverine
- Paregoric
- Paroxetine
- Pasireotide
- Pazopanib
- Pentamidine
- Pentazocine
- Pentobarbital
- Perampanel
- Perphenazine
- Phenobarbital
- Pimavanserin
- Pimozide
- Pipamperone
- Pipenzolate Bromide
- Pirenzepine
- Piritramide
- Pitolisant
- Ponesimod
- Posaconazole
- Potassium Oxybate
- Prazepam
- Pregabalin
- Primidone
- Probucol
- Procainamide
- Prochlorperazine
- Procyclidine
- Promethazine
- Propafenone
- Propantheline
- Propiverine
- Propofol
- Protriptyline
- Quazepam
- Quetiapine
- Quinidine
- Quinine
- Ramelteon
- Ranolazine
- Remifentanil
- Remimazolam
- Revefenacin
- Ribociclib
- Rifampin
- Risperidone
- Scopolamine
- Secobarbital
- Secretin Human
- Selpercatinib
- Sertindole
- Sertraline
- Sevoflurane
- Siponimod
- Sodium Oxybate
- Sodium Phosphate
- Sodium Phosphate, Dibasic
- Sodium Phosphate, Monobasic
- Solifenacin
- Sorafenib
- Sotalol
- Stramonium
- Sufentanil
- Sulpiride
- Sultopride
- Sunitinib
- Tacrolimus
- Tamoxifen
- Tapentadol
- Telavancin
- Temazepam
- Teriflunomide
- Terodiline
- Tetrabenazine
- Thiopental
- Thioridazine
- Thiothixene
- Tilidine
- Tiotropium
- Tizanidine
- Tolterodine
- Topiramate
- Toremifene
- Tramadol
- Trazodone
- Triazolam
- Triclabendazole
- Trifluoperazine
- Trihexyphenidyl
- Trimipramine
- Triptorelin
- Tropicamide
- Trospium
- Umeclidinium
- Vandetanib
- Vardenafil
- Vemurafenib
- Venlafaxine
- Vilanterol
- Vinflunine
- Voclosporin
- Voriconazole
- Vorinostat
- Zaleplon
- Zolpidem
- Zopiclone
- Zotepine
- Zuclopenthixol
How much does Phenobarbital cost?
$8.12
Phenobarbital contraindications for pets
Contraindications are specific health conditions or situations in which a pet should not take a medication due to safety concerns. If your pet has any of the following conditions or if any of the following apply to your pet, let your veterinarian know because Phenobarbital will not be safe for your pet to take.
- Allergic to other barbiturates
- Liver problems
- Severe kidney problems
- Severe lung problems
What are alternatives to Phenobarbital for pets?
News about Phenobarbital
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