What to Do If Your Dog Has a Seizure After Starting Medication

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-08-14

Key Takeaways

• Immediate cessation of the suspect medication and prompt veterinary consultation (regular veterinarian or emergency clinic) is paramount if a dog experiences a seizure after initiating a new drug.
• Seizure duration exceeding five minutes, recurrent seizures without recovery, or post-ictal signs such as collapse, unresponsiveness, or respiratory distress necessitate immediate emergency veterinary intervention.
• Adverse drug reactions, where medications lower the seizure threshold or cause neurological disruption, are the primary suspected cause, though underlying conditions or other toxicities must be ruled out by a veterinarian through physical examination and diagnostic testing (e.g., blood work, imaging).
• Accurate reporting of critical details to the veterinarian, including the exact drug name, strength, dose administered, timing of administration relative to the seizure, seizure duration, and observed clinical signs, is crucial for accurate diagnosis and treatment planning.
• Veterinary assessment may involve neurological examination, blood tests (e.g., complete blood count, chemistry panel to assess organ function, blood glucose, and electrolytes), and potentially advanced diagnostics like MRI or CT scans to identify the seizure etiology and guide therapeutic decisions.
• Never adjust medication doses or stop prescribed treatments without explicit veterinary guidance, as incorrect dosing or abrupt cessation can lead to adverse effects, withdrawal symptoms, or a rebound of the original condition.

If your dog has a seizure after starting a new medication, stop giving the drug immediately and call your veterinarian or an emergency veterinary clinic right away. A seizure can be a serious adverse reaction, and in some cases it signals a life-threatening emergency. Do not wait to see if another seizure happens. Do not try to manage this at home. Your first call should be to a veterinary professional who knows your dog's history and the medication involved.

While you are on the phone or driving to the clinic, keep yourself and your dog safe. Move your dog away from stairs, furniture edges, and water. Do not put anything in their mouth. Do not hold them down. Time the seizure if you can. A seizure that lasts longer than five minutes, or multiple seizures without full recovery in between, is an emergency that requires immediate in-person care. Even if the seizure stops quickly, you still need veterinary guidance because the underlying cause is unknown and the medication may need to be changed or stopped.

Is This an Emergency?

Use the table below to decide your next step. When in doubt, choose the emergency level. A seizure after a new medication is never something to ignore.

{
 "type": "triage",
 "title": "Urgency triage by severity of signs",
 "tiers": [
  {
   "tier": "danger",
   "label": "Go to an emergency vet now",
   "signs": [
    "Seizure lasts longer than 5 minutes",
    "Seizures happen back to back without your dog waking up between them",
    "Your dog cannot stand, is limp, or is unconscious after the seizure stops",
    "Your dog has trouble breathing, gums look pale, blue, or white, or your dog collapses"
   ],
   "action": [
    "Call the emergency clinic on the way so they are ready",
    "Transport your dog safely in a carrier or on a flat surface",
    "Do not give any more of the medication"
   ]
  },
  {
   "tier": "warn",
   "label": "Book a same-day appointment",
   "signs": [
    "A single seizure that stops within 2 to 3 minutes, and your dog recovers fully within 10 to 15 minutes",
    "Your dog is alert, walking normally, eating, and drinking after the episode",
    "You are unsure if the seizure was caused by the medication or something else"
   ],
   "action": [
    "Call your regular veterinarian today",
    "Tell them the drug name, the dose you gave, and the time of the seizure",
    "Ask whether to stop the medication until they examine your dog"
   ]
  },
  {
   "tier": "safe",
   "label": "Watch at home for a defined period",
   "signs": [
    "No seizure has occurred, but you are worried about possible side effects",
    "Your dog seems drowsy, wobbly, or mildly uncoordinated shortly after a dose",
    "These signs may be normal for some medications, but they can also be early warning signs"
   ],
   "action": [
    "Observe your dog closely for the next 2 to 4 hours",
    "Keep them in a quiet, safe room",
    "If wobbliness worsens, if your dog seems confused, or if any twitching starts, move to the emergency level"
   ]
  }
 ]
}

What Is Most Likely Going On?

The most likely explanation is that your dog is having an adverse drug reaction. This means the medication is causing an unwanted effect on the nervous system. Some drugs lower the seizure threshold, which is the level of brain activity needed to trigger a seizure. In a dog that already has a tendency toward seizures, even a small change can set one off. In other cases, a dog with no seizure history can still react to a drug. The US Food and Drug Administration tracks reports of adverse events for approved animal drugs, and seizures are among the reactions that can be reported for certain medications. This is why the FDA advises pet owners to give medications exactly as prescribed and to watch for unusual signs after a dose.

The timing matters. A seizure that happens within hours of giving a new pill points strongly to the medication. A seizure that happens days later could still be related, especially if the drug builds up in the body. Your veterinarian will need the exact time of the last dose and the time of the seizure to sort this out.

What Else Could It Be?

A seizure after starting a medication is not always caused by the drug. The condition that the medication was meant to treat could be the cause. For example, if your dog is on an anti-seizure drug and still has a seizure, the dose may be too low or the drug may not be the right one for your dog's type of epilepsy. If your dog is being treated for a heart condition, a metabolic problem, or an infection, any of those underlying diseases could also trigger a seizure on their own.

Other possible causes include accidental ingestion of something toxic, a head injury, low blood sugar, or a brain condition such as a tumor. These possibilities cannot be ruled out without a veterinary examination. The MSD Veterinary Manual notes that seizures have many causes, and identifying the specific trigger often requires blood work, a physical exam, and sometimes imaging. Do not assume the medication is the only explanation, and do not assume it is harmless. Your veterinarian needs to investigate.

What Should You Tell the Veterinarian?

Write down or say these details clearly. The drug name and strength, which you can read from the bottle. The exact dose you gave, meaning how many pills or milliliters. The time you gave the last dose. The time the seizure started and how long it lasted. What your dog looked like during the seizure, for example whether they paddled their legs, drooled, lost bladder control, or seemed unaware of you. How your dog behaved after the seizure, including how long it took to stand or respond normally. Whether this is the first dose or a later dose. Any other medications, supplements, or flea and tick products your dog receives. Any history of seizures or head trauma.

This information helps the veterinarian decide whether to stop the drug, change the dose, or switch to a different medication. Dosing changes must come from your veterinarian. Never adjust the dose yourself, because giving too much of one drug or too little of another can cause serious harm. The FDA's guidance on safe use of pet medications emphasizes that dosing errors are a common cause of problems, and that owners should confirm the dose and schedule with their veterinarian before making any changes.

What Happens Next at the Clinic

Your veterinarian will examine your dog and may run blood tests to check organ function, blood sugar, and electrolyte levels. They may ask about any other exposures, such as household toxins or recent changes in diet. If the seizure was brief and your dog recovers fully, the veterinarian may recommend stopping the medication and monitoring at home. If the seizure was severe or repeated, your dog may need to stay in the hospital for observation and supportive care.

In some cases, the veterinarian will prescribe a different medication to control seizures. That decision depends on your dog's overall health, the reason for the original drug, and the severity of the reaction. The American Veterinary Medical Association advises pet owners to work closely with their veterinarian when a drug causes a problem, because the safest next step depends on the specific situation. You should also report the reaction to the FDA, because adverse event reports help regulators identify safety problems with approved drugs. Your veterinarian can guide you through that reporting process.

The most important thing is to act quickly and keep your dog safe. A seizure is frightening to watch, but your calm response and clear communication with your veterinarian will give your dog the best chance of a good outcome.

What You Can Do Right Now at Home

Your first job is to keep your dog physically safe during the seizure. Move furniture out of the way if you can. Cushion your dog's head with a folded towel. Do not put anything in the mouth. A dog cannot swallow its tongue, and you risk being bitten or breaking a tooth. Do not hold your dog down. Do not try to stop the jerking movements. Do not give water, food, or any medication during the seizure.

Time the seizure from the moment it starts to the moment the movements stop. A seizure that lasts longer than five minutes is a medical emergency. A cluster of two or more seizures within 24 hours is also an emergency. If either happens, go to an emergency veterinary clinic now.

After the seizure stops, your dog may be confused, restless, or temporarily blind. This is called the post-ictal phase. Keep the room quiet and dim. Stay close but do not force interaction. Let your dog rest. Offer water only when your dog is fully alert and standing steadily.

Do not give a second dose of the medication that may have caused the seizure. Do not stop a long-term seizure medication without veterinary direction, either. The correct next step depends on what drug your dog is on and why. Only your veterinarian can make that call.

What to Write Down Before You Call

Write down the details while they are fresh. Your veterinarian will need this information to decide the next step. Use your phone's notes app or a scrap of paper. The following checklist covers the essentials.

Keep a running log if seizures happen more than once. A simple table with the date, time, duration, and notes is enough. Bring this log to your veterinary visit. Patterns that are hard to see in the moment become clear on paper.

What the Veterinary Visit Usually Involves

Your veterinarian will ask about the seizure itself and about your dog's history. Expect questions about age, breed, prior illnesses, and any other medications. Be ready to describe the seizure in detail. A video of the seizure, if you can safely record one, is extremely helpful. Many owners cannot describe the movements accurately under stress.

The physical exam comes first. Your veterinarian will check your dog's heart, lungs, temperature, and neurologic responses. Blood work is commonly recommended. A complete blood count and a chemistry panel check organ function, blood sugar, and electrolyte balance. These tests can reveal problems like low calcium or liver disease that cause seizures.

Depending on the findings, your veterinarian may suggest more testing. Bile acid testing checks liver function more deeply. Blood pressure measurement rules out hypertension. Imaging, such as an MRI or CT scan, looks for structural brain problems. These advanced tests are not always needed on the first visit. Your veterinarian will tailor the workup to your dog's specific situation.

The cost of this visit varies widely. A basic exam with blood work often falls in the range of $150 to $400. Advanced imaging can run from $1,000 to $3,000 or more. Prices depend heavily on your region, the clinic, and whether emergency after-hours care is involved. Ask for a written estimate before any expensive test is performed. The US Food and Drug Administration provides general guidance on safe medication use, and your veterinarian is the only person who can determine the correct dose for your dog. Dosing depends on body weight, kidney and liver function, and the specific drug prescribed. A dose that is safe for one dog can be harmful to another.

How the Medication Decision Gets Made

Your veterinarian will weigh several factors when deciding whether to continue, change, or stop the medication. The first question is whether the seizure was truly caused by the drug. Some seizures happen by coincidence. A dog with epilepsy can have a seizure on any given day, whether or not it is on medication.

The second question is the drug's known side effect profile. Some medications are more likely to lower the seizure threshold than others. Your veterinarian knows which drugs carry this risk. The third question is why your dog was taking the medication in the first place. If it was treating an infection or pain, a different drug may be available. If it was treating seizures, the approach is different.

Never adjust the dose on your own. The FDA warns that giving the wrong amount of a pet medication is a common and preventable error. Measure carefully, use the syringe or dropper provided, and follow the label exactly. If you have any doubt about the dose you gave, say so to your veterinarian.

When to Go Straight to the Emergency Room

Some situations do not wait for a phone call. Go to the nearest emergency veterinary clinic immediately if any of the following occur.

• The seizure lasts longer than five minutes.
• Your dog has two or more seizures in 24 hours.
• Your dog does not regain consciousness between seizures.
• Your dog has trouble breathing after the seizure.
• Your dog's gums are pale, white, or blue.
• Your dog collapses or cannot stand after the seizure ends.
• Your dog is pregnant, very young, or very old.
• Your dog has a known heart condition or diabetes.

These signs can indicate a life-threatening problem. Do not wait to see if your dog improves. Do not try to manage this at home. Hands-on emergency care is required, and no phone call or online advice can replace it. The American Veterinary Medical Association maintains resources for pet owners on recognizing emergencies and seeking prompt care. When in doubt, call your veterinarian on the way to the clinic. But go.

Common Mistakes Owners Make After a Seizure

Mistake: Giving another dose of the medication right away. After a seizure, many owners assume the first dose failed and give more. This can cause a dangerous overdose. Do not give any additional medication until a veterinarian tells you to. Write down the exact time of the seizure and the time of the last dose, then call your vet or an emergency clinic immediately.

Mistake: Assuming the seizure is unrelated to the new drug. A seizure within days or weeks of starting a new medication is a red flag. Even if your dog has never seized before, the timing matters. Report the medication name, dose, and start date to the vet. The FDA tracks adverse drug events in animals, and your report can help others. You can find information on reporting through the FDA Center for Veterinary Medicine.

Mistake: Waiting to see if another seizure happens before calling. One seizure after starting a medication is enough to warrant a call. Do not wait for a second event. Seizures can cluster, and a prolonged seizure is a life-threatening emergency.

Mistake: Trying to restrain or hold the dog during the seizure. You cannot stop a seizure by holding the dog. Restraint can cause injury to you or your pet. Move furniture away, cushion the head if safe, and time the seizure. Do not put anything in the mouth.

How to Reduce the Chance of It Happening Again

The most important step is identifying whether the medication caused the seizure. Your veterinarian may stop the drug, lower the dose, or switch to a different class of medication. Never change the dose on your own.

Give medications exactly as prescribed. Use a pill cutter or syringe for liquids, and double-check the label each time. The FDA advises pet owners to confirm the drug name and strength before every dose to avoid errors.

Keep a seizure log. Record the date, time, duration, and what the dog was doing before the seizure. Note any other signs like drooling, pacing, or confusion after the event. This log helps the vet see patterns.

Avoid triggers where possible. Stress, missed doses, and sudden changes in routine can lower the seizure threshold in some dogs. Keep feeding and walking times steady.

What Recovery and Ongoing Management Usually Look Like

Most single seizures last under two minutes. Afterward, the dog may be disoriented, wobbly, or sleepy for minutes to hours. This is called the post-ictal phase. Keep the dog in a quiet, dim room and offer water once they are fully alert.

If the medication is changed, your vet may taper the old drug while starting the new one. This transition can take days to weeks. During that time, watch closely for any new signs.

If the seizure was a one-time reaction, the dog may return to normal quickly. If the dog has an underlying seizure disorder, long-term medication may be needed. That decision is made by your vet based on the dog's history, bloodwork, and response to treatment.

Recovery time varies. Some dogs are back to normal within a day. Others need several days of rest. Follow your vet's instructions for activity and follow-up visits. The American Veterinary Medical Association recommends keeping a close relationship with your veterinarian for ongoing health decisions.

Frequently Asked Questions

Can I give my dog a smaller dose of the seizure medication to be safe? No. Changing the dose without veterinary guidance can cause the drug to be ineffective or unsafe. Seizure medications have a narrow window where they work properly. Too little may not prevent seizures, and too much can cause sedation, wobbliness, or worse. Your veterinarian calculates the dose based on your dog's weight, liver function, and the specific drug. Call your vet if you are worried about side effects. They may adjust the dose, but only they can decide how.

What if my dog has another seizure while I am waiting for the vet to call back? Time the seizure. If it lasts longer than five minutes, or if your dog has two or more seizures within 24 hours, go to an emergency clinic immediately. Prolonged seizures can cause brain damage or overheating. While waiting, keep the dog away from stairs and sharp objects. Do not give any medication. Call the emergency clinic on the way so they are prepared.

Should I stop the medication right now? Do not stop any prescription medication without veterinary instruction. Stopping suddenly can cause withdrawal effects or a rebound of the original condition the drug was treating. Your vet needs to weigh the risk of another seizure against the reason the drug was prescribed. Call your vet or an emergency service for guidance. If you cannot reach anyone, go to an emergency clinic.

How long after starting a drug can a seizure happen? It depends on the drug. Some reactions happen within hours of the first dose. Others appear after several days or weeks as the drug builds up in the body. This is why the timing of the seizure relative to the medication start date is so important. Tell your vet exactly when the drug was started and when the seizure occurred. This information helps them determine if the drug is the likely cause.

Will my dog need to be on seizure medication for life? Not necessarily. If the seizure was a one-time reaction to a drug, the dog may never seize again once that drug is stopped. If the dog has epilepsy or another brain condition, long-term treatment may be needed. Your vet will base this decision on diagnostic tests, the seizure pattern, and how the dog responds. Many dogs live full, active lives on daily seizure medication.

Can I report the seizure to the FDA myself? Yes. The FDA Center for Veterinary Medicine accepts adverse event reports from pet owners. Your veterinarian can also file a report. Include the drug name, lot number if available, the dose, and a description of the seizure. Reporting helps regulators identify safety problems with animal drugs. Your vet may already be planning to report it, but you can ask them to confirm.

Related Clinical & Scientific Guides

• What Are the Side Effects of Bravecto for Dogs? What to Watch For
• Can You Give Your Dog Human Allergy Medicine? Whats Safe
• Can You Give Your Dog Dramamine for Car Sickness?

References and Further Reading

• FDA Center for Veterinary Medicine Animal Drug Information
• FDA Safe Use of Pet Medications
• AVMA Pet Owner Resources
• MSD Veterinary Manual Pet Owner Version
• AAHA Pet Owner Resources

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• What to Do If Your Dog Is Lethargic After Starting a New Medication
• What to Do If Your Dog Has a Bad Reaction to Flea Medication
• What to Do If Your Dog Vomits After Taking Medication
• What to Do If Your Dog Is Panting Excessively After Starting Steroids

This article is general educational information for pet owners. It is not a substitute for veterinary diagnosis, examination, or treatment. If your pet is showing severe or rapidly worsening signs, contact an emergency veterinary hospital immediately.