{"id":631911,"date":"2025-04-10T18:49:11","date_gmt":"2025-04-10T22:49:11","guid":{"rendered":"https:\/\/www.singlecare.com\/blog\/?p=631911"},"modified":"2026-05-04T18:51:57","modified_gmt":"2026-05-04T22:51:57","slug":"side-effects-of-phenobarbital-in-dogs","status":"publish","type":"post","link":"https:\/\/www.singlecare.com\/blog\/side-effects-of-phenobarbital-in-dogs\/","title":{"rendered":"What are the side effects of phenobarbital in dogs?"},"content":{"rendered":"

Phenobarbital<\/span><\/a> is a long-acting<\/span> barbiturate<\/span><\/a> (a class of depressant drugs) used in veterinary medicine to control or prevent seizures in dogs. It works by increasing the seizure threshold in the brain, reducing the likelihood and severity of seizures. Dogs taking phenobarbital may experience mild short-term side effects, and more serious side effects are possible with long-term use, which is why regular blood testing is important to monitor liver function and blood counts.<\/span><\/p>\n\t\t

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What is phenobarbital used for in dogs?<\/span><\/h2>\n

Anticonvulsant medications<\/span><\/a> (also called antiepileptic drugs) are commonly used to treat seizures and epilepsy in dogs. Phenobarbital is one of the most widely prescribed, and Fidoquel CA-1, a brand of phenobarbital labeled for dogs, has been<\/span> conditionally <\/span>approved by the FDA<\/span><\/a> to control seizures in dogs.<\/span><\/p>\n

Barbiturates work by<\/span> increasing gamma-aminobutyric acid (GABA)<\/span><\/a>, a neurotransmitter that slows nerve activity and reduces seizures. Phenobarbital is most commonly given orally as tablets or intravenously, but it can also be compounded into a topical gel applied to the skin.<\/span><\/p>\n

How is phenobarbital dosed in dogs?<\/span><\/h3>\n

The<\/span> phenobarbital dosage<\/span><\/a> depends on the dog’s condition. For severe cases, a higher dose is given immediately. “High-dose phenobarbital is used mainly when you are loading a patient,” says Jason Horgan, DVM, of<\/span> LeadER Animal Specialty Hospital<\/span><\/a> in South Florida. Loading refers to rapidly building up therapeutic drug levels in the bloodstream to stop ongoing seizure activity quickly. Once those levels are reached, lower maintenance doses become the standard.<\/span><\/p>\n

Phenobarbital can also be used alongside other medications. “Low doses of this medication are used for the management of pets who have rare or inconsistent seizures, [and sometimes a low dose is used] along with a combination of anti-seizure medications to obtain adequate seizure control,” says Nita Vasudevan, DVM, a veterinarian at<\/span> Embrace Pet Insurance<\/span><\/a> in Orlando, Florida. “High doses are used in pets who have more severe or cluster seizures, or some pets who are still refractory, even with a combination of seizure medications.”<\/span><\/p>\n

Your veterinarian can advise on the best dosing approach for your dog.<\/span><\/p>\n

What are the side effects of phenobarbital in dogs?<\/span><\/h2>\n

Phenobarbital can cause a variety of short-term side effects in dogs. Common side effects of phenobarbital in dogs include:<\/span><\/p>\n