A newly published European safety review recommends additional warnings and monitoring information for veterinary medicines containing phenobarbital. The review does not announce a ban, recall or suspension. EU regulators concluded that the medicines’ overall balance of benefits and risks remains unchanged. For owners, the main message is straightforward: continue treatment exactly as prescribed, keep accurate records and discuss appropriate monitoring with the treating veterinarian. What did European regulators review? National veterinary authorities identified an increase in reports involving several medical conditions in animals receiving phenobarbital. A targeted signal-management procedure began in April 2024 and concluded in May 2026. The review examined reports concerning: pancreatitis in dogs; elevated cholesterol or triglycerides in dogs; elevated liver enzymes in dogs; anticonvulsant hypersensitivity syndrome in dogs and cats. A safety signal does not automatically prove that a medicine caused an event. It means that information from adverse-event reports, scientific literature, clinical studies or other sources requires structured investigation. Following its review, the EU regulatory group recommended updates to the authorised product information. Pancreatitis will be added as an uncommon adverse event in dogs The regulators recommended listing pancreatitis as an uncommon adverse event for dogs treated with phenobarbital. They also concluded that concurrent treatment with potassium bromide increases the risk. Potassium bromide is another medicine that may be used to control seizures, sometimes in combination with phenobarbital. This finding does not mean that every dog receiving one or both medicines will develop pancreatitis. It means that veterinarians and owners should be aware of the risk and respond appropriately to unexplained illness. Possible signs associated with pancreatitis can overlap with many other conditions. They may include vomiting, reduced appetite, abdominal discomfort, weakness or unusual lethargy. Owners should not attempt to diagnose pancreatitis at home; veterinary examination and testing are required. Regulators recommend monitoring blood lipids The review recommends periodic monitoring of serum lipids, including cholesterol and triglycerides, in dogs receiving phenobarbital. Elevated blood lipids cannot usually be recognised through home observation alone. They require laboratory testing. The appropriate test schedule depends on the individual dog, its treatment duration, other medicines, previous results and wider health history. Owners can help by maintaining a record of: phenobarbital doses and administration times; other medicines and supplements; laboratory results; seizure frequency and duration; changes in appetite, weight or behaviour; vomiting or other new symptoms. This information helps the veterinary team interpret changes over time rather than relying on a single result. Elevated liver enzymes do not always mean liver failure Elevated liver enzymes are to be listed as a common adverse event in dogs receiving phenobarbital. However, the recommended product information specifically notes that this finding may not necessarily indicate liver dysfunction. This distinction is important. Phenobarbital can affect certain laboratory measurements, but an abnormal result still needs to be interpreted by a veterinarian alongside: the dog’s symptoms and physical examination; previous blood results; the length of treatment; the phenobarbital dose or blood concentration; other medicines and health conditions; additional tests when clinically appropriate. Owners should not change treatment based solely on an isolated laboratory value. A serious hypersensitivity risk was identified in cats The EU review found evidence supporting a likely causal association between phenobarbital treatment and anticonvulsant hypersensitivity syndrome in cats. Regulators described this event as serious and preventable. They also noted that it occurred in a non-target species following use outside the terms of the marketing authorisation. That does not mean phenobarbital can never be used in a cat. Veterinarians may sometimes prescribe medicines outside their standard authorised terms when they judge this clinically necessary and legally appropriate. Such decisions require individual assessment and careful monitoring. Owners should ensure that the veterinarian knows about every medicine and supplement the cat receives. Any unexpected illness following the introduction of phenobarbital should be reported promptly rather than waiting for the next routine appointment. The review did not reach the same conclusion for hypersensitivity syndrome in dogs. Instead, regulators requested continued close monitoring of reports in dogs. Should owners stop phenobarbital? No owner should suddenly stop or alter phenobarbital without veterinary instructions. Abrupt withdrawal or missed doses can lead to loss of seizure control and may create a medical emergency. Even when an adverse effect is suspected, the veterinarian must balance that concern against the risk of further seizures. Depending on the circumstances, the veterinary plan may involve: an urgent examination; blood tests; measurement of phenobarbital concentration; closer observation; adjustment of the treatment plan; gradual transition to another medicine when appropriate. The correct response depends on the individual animal. There is no safe universal adjustment owners can make independently. What should owners discuss with their veterinarian? At the next scheduled review, owners of animals receiving phenobarbital can ask: Which laboratory tests does my pet need? How often should phenobarbital concentration be measured? Should cholesterol and triglycerides be added to the monitoring plan? How should changes in liver enzymes be interpreted? Does another prescribed medicine affect the risk of adverse events? What symptoms require an urgent call? What should I do if a dose is missed or vomited? How should suspected adverse effects be reported? Owners whose dogs receive both phenobarbital and potassium bromide should specifically discuss the newly highlighted pancreatitis risk. Keep a consistent seizure diary A seizure diary can help determine whether treatment is controlling the condition and whether changes coincide with dose adjustments or other events. Each record should ideally include: date and approximate start time; estimated duration; what the animal was doing beforehand; visible signs during the episode; recovery time and behaviour afterward; whether medication was given as scheduled; possible illness, travel or unusual stress; a video, when recording can be done safely. A series of consistent records is usually more useful than relying on memory during a consultation. What the regulatory decision means The European review reached a balanced conclusion. Confirmed facts: Updated risk and monitoring information has been recommended. Pancreatitis is to be listed as uncommon in dogs. Combined treatment with potassium bromide increases that risk. Periodic monitoring of cholesterol and triglycerides is recommended. Elevated liver enzymes are common but do not necessarily indicate liver dysfunction. Evidence supports a likely association with anticonvulsant hypersensitivity syndrome in cats treated outside the authorised terms. The overall benefit-risk balance remains unchanged. What remains uncertain or individual: Whether a particular symptom was caused by phenobarbital. How frequently each animal should undergo testing. Whether treatment should be adjusted. How national product information will apply to a specific brand and country. National translations of the recommended product-information changes were still being completed when the EMA information was published on 4 September 2026. Owners and veterinarians should therefore consult the current information for the exact product being used. The practical takeaway Phenobarbital remains an important medicine for controlling seizures. The new recommendations strengthen the information available for using it safely; they do not invalidate existing treatment. The safest approach is to: administer every dose exactly as prescribed; never stop treatment abruptly; record seizures, doses and possible adverse effects; attend scheduled blood tests; tell the veterinarian about all other medicines; seek advice promptly when the animal becomes unexpectedly unwell. Accurate records and regular veterinary review allow treatment to be adjusted using the animal’s actual clinical history—not fear or incomplete information.
Phenobarbital for Dogs and Cats: New EU Safety Recommendations Explained
Phenobarbital is an important veterinary medicine used to control epileptic seizures, particularly in dogs. Because treatment is often long-term, regulators continually evaluate suspected adverse events reported after medicines reach the market.
