Is Cyclobenzaprine (Flexeril) Safe for Dogs?
Why it’s a problem
Cyclobenzaprine behaves like certain antidepressants in the body, affecting brain and heart signaling. Dogs that eat tablets can become profoundly sedated and then develop tremors, seizures, and abnormal heart rhythms, and reactions vary unpredictably between individuals. Human tablet sizes are large relative to small dogs, and there is no home antidote.
How to keep your pet safe
Store muscle relaxants in a locked or high cabinet and keep weekly organizers closed. Never give your own tablets for a dog’s back pain or strain — vets use safer, dose-appropriate options such as methocarbamol for dogs. Count tablets if a bottle has been left out.
Warning signs to watch for
Severe drowsiness, stumbling, drooling, vomiting, slow breathing, tremors, seizures, abnormal heartbeat, low body temperature.
When to call the vet
Call a vet or pet poison hotline immediately after any ingestion, even if the dog only seems sleepy — signs can deepen over hours. Bring the bottle and estimate how many tablets are missing. Do not wait for seizures before calling.
Common questions
My dog ate a Flexeril pill and is very sleepy — should I wait?
No. Sedation from cyclobenzaprine can deepen into tremors, seizures, and heart rhythm problems. Call a vet or pet poison hotline immediately with the dose and your dog’s weight.
Can I give my dog Flexeril for a pulled muscle?
Never self-dose. Vets prescribe dog-appropriate muscle relaxants such as methocarbamol at calculated doses. Human cyclobenzaprine can cause seizures and arrhythmias in dogs.
More medications hazards for dogs
This page is general educational information, not a substitute for professional veterinary advice. Every pet is different — if your animal ate or touched something concerning, contact your veterinarian or a pet poison hotline right away. In the US: Pet Poison Helpline (855) 764-7661, ASPCA Animal Poison Control (888) 426-4435 (fees may apply).