Will Flexeril Hurt My Dog?

Flexeril is a skeletal muscle relaxant to help reduce muscle pain in dogs. “Will Flexeril hurt my dog if I give it to him above the recommended dosage? He is in a lot of pain.” We will answer this query from one of our readers here.

Your dog may suffer from pain just like human beings. Arthritis, injury, or post-surgery can cause severe pain. But unfortunately, he cannot show or talk about this pain. You need to be sensitive to the indicators, identify the suffering, and provide the necessary treatments to make your dog comfortable.

A muscle relaxer may help your dog get relief from painful muscle spasms. But are these medicines safe? For example, will Flexeril hurt your dog if it overdoses on it?

Will Flexeril Hurt My Dog

In this article, we will discuss questions related to Flexeril and other muscle relaxers, when you should give them to your dog and whether it is a good idea to do so. Keep on reading the article for more information.

Will Flexeril Hurt My Dog?

What is Flexeril?

Flexeril(Cyclobenzaprine) is a muscle relaxant that works by blocking nerve impulses sent to the brain. It is used to treat muscle conditions like injury, spasms, or pain.

It is usually only recommended for acute muscle spasms. The drug is easily absorbed and can show its peak impact within three to eight hours of administering. 

What is a toxic dose of Flexeril for a dog?

The toxic dosage is 12mg per 2.2 pounds of body weight. If your dog is 40 pounds, the poisonous dodge will be 218 mg. If you give a 10 mg tablet to your 40 pounds dog, he will not have any toxic effect on his body. 

However, your dog can see some side effects, like confusion, slow heart rate, reduced breathing rate, depression, ataxia, or inability to urinate. 

Will Flexeril Hurt My Dog

What to do if your dog is overdosing on Flexeril?

The drug usually hangs around in the dog’s body for a long time, but the peak plasma levels are high in 3 to 8 hours after ingestion. If your dog doesn’t show any signs of side effects two to eight hours after ingestion of Flexeril, you don’t need to worry about him.

However, the best idea is to take your dog to a veterinary doctor. The doctor may induce vomiting or administer activated charcoal or intravenous fluids if recently ingested Flexeril tablets. A respirator system or ventilator can be provided to your dog if needed.

The other option can be to supervise your dog at home closely. If you find any symptoms in your dog, like vomiting or difficulty urinating, take him to the clinic for treatment.

What Are Muscle Relaxers?

Muscle relaxers are medicines that can relax the muscles of your pet dog. It reduces muscle spasms, stiffness, or any discomfort experienced by your furry friend.

Some muscle relaxers directly affect the muscles of the dog’s body, whereas other medicines act on your dog’s nervous system.

Although muscle relaxers are beneficial, they do not heal injuries or any disorders. They can only help reduce the sensation of pain associated with the disorder.

What Are Common Types Of Dog Muscle Relaxers?

There are numerous muscle relaxers for dogs. But every muscle relaxer does not give identical results. So, you must find out which one is best for your dog. I strongly advise you to ask the veterinary doctor about any muscle relaxer before giving it to your furry friend.

I am listing below some of the common muscle relaxers for dogs.


Guaifenesin is also known as glyceryl guaiacolate. It is used as support when your furry friend is given anesthesia for surgeries. It even helps relax the larynx and pharynx muscles without affecting the diaphragm.


Rimadyl is an anti-inflammatory drug that helps in reducing the pain associated with arthritis in dogs. You can use Rimadyl for a short treatment period or daily treatment for joint deterioration or inflammation in your dog.

Will Flexeril Hurt My Dog


Methocarbamol is one of the commonly used muscle relaxers in dogs. It provides relief for inflammatory muscle conditions and even reduces muscle spasms. Methocarbamol is available under various brand names like Robaxin, Robinax, and Robaximol. 

You need to remember that this medication is not available over the counter. So you need a prescription to purchase methocarbamol for your dog. It is safe for your dog, but you need to be extra cautious if your furry friend is sick or pregnant.

It is available in tablet and injected liquid form. The injected liquid form will affect your dog immediately, but the pill form will nearly take one hour to affect your dog. The veterinary doctor uses injectable methocarbamol in emergencies like poisoning and trauma so that it will work faster on your dog.

Dog owners can use the pill form at home to reduce the muscle spasm in their dogs.


The dantrolene directly affects the muscles of your dog rather than the nervous system. It helps treat malignant hyperthermia. It is a severe reaction in which your dog will have elevated body temperature, muscle spasms, and a rapid heartbeat.

#5. Cyclobenzaprine

Flexeril(Cyclobenzaprine) can be used for acute muscle spasms. It is usually absorbed after an oral dosage with peak plasma levels three to eight hours after ingestion. 

If you give a 10 mg tablet to your 40 -45 pound, it will not be poisonous, but it can have side effects like depression and ataxia. 

Remember, higher dosages of Flexeril can be poisonous for your furry friend and can lead to death. For instance, if you give 218 mg of Flexeril tablets to your 40-pound dog then it can be poisonous for him.

Will Flexeril Hurt My Dog

When Should I Give Muscle Relaxer To My Dog?

Muscle relaxers can reduce muscle pain or stiffness in your furry friend when home remedies are ineffective. There are various muscle relaxers available on the market. You can use over-the-counter medications on your dog, but it’s better to consult your veterinary doctor before giving any muscle relaxer to your dog.

Your dog can experience muscle pain because of numerous reasons. For instance, the muscles can over-exert while playing for an extended period and cause pain. 

Again, exercising your dog on hard surfaces will put extra strain on your dog’s muscles, which leads to soreness. So, you always need to get your dog to practice exercises on soft ground or ground covered with grass or carpet.

Exercise is quite essential for your dog. But overexercising can have negative consequences on the body of your dog. So you need to watch the signs and symptoms in your dog’s behavior to know when he is feeling tired and should rest appropriately.

If you have an older dog, he may also experience muscle pain or joint pain because of arthritis. 

Will Flexeril Hurt My Dog

Lastly, keep in mind that your dog may find it challenging to consume the pill form. So, you can consider options like putting the pill in his favorite food so that he will ingest it. You can praise your dog or give him a small treat after giving medications.

Signs And Symptoms Of Muscle Pain In Dog

Your dog cannot tell you about his muscle pain. So, I am listing a few signs and symptoms that will help you know that your furry friend is having muscle pain.

  • Crying
  • Howling
  • Panting excessively
  • Hunched posture
  • Staring at you
  • Limping

What Are The Side Effects of Muscle Relaxants?

If you are giving muscle relaxers to your dog, then there are chances of potential side effects. The effect can range from small to deadly depending on the type of muscle relaxer you have given your dog and the amount of dosage. 

The side effects also depend upon whether the muscle relaxer you have given your furry friend affects muscles or the nervous system directly.

The muscle relaxer that affects the nervous system is a bit more potent than the one directly affecting muscles. It may cause your dog’s spinal cord and brain to malfunction and permanently damage it. It can have an adverse effect on the brain and heart of your dog.

Will Flexeril Hurt My Dog

There are other side effects of giving muscle relaxers to your dog. I am listing them below.

  • Drowsiness
  • Urine becomes dark
  • Drooling
  • Vomiting
  • Swelling
  • Stumbling
  • Respiratory problem

If you have given overdosages to your dog, then you need to take him to the veterinary doctor immediately to counteract the effects. I am listing a few signs of giving overdosage of muscle relaxers to your dog.

  • Drooling
  • Vomiting
  • Sedation
  • Incoordination

Frequently Asked Questions

#1. Can I give my dog a human Flexeril?

More than 12.2mg per 2.2-pound weight of Flexeril can be toxic for the dog.

If you give your dog 1.1 mg per 2.2 pounds of body weight, it will not have any toxic effect. However, your dog can have some side effects like vomiting, drooling or heartbeat becoming high. The truly toxic dosage of Flexeril is 12.2 mg per 2.2 pounds of your dog’s body weight.

#2. What happens if a dog eats a muscle relaxer?

You should only administer dog-specific muscle relaxers to your dog, that too in prescribed dosages.

Your dog can eat a muscle relaxer only if it is meant for him. For instance, you can give your dog methocarbamol to reduce muscle spasms and inflammation. 

Methocarbamol is available in 500 mg tablets, and you can purchase it only after having a prescription from a veterinary doctor. But still, I will suggest you to better consult your veterinary doctor before giving any over-the-counter muscle relaxer to your dog. 

If your dog eats a muscle relaxer meant for human beings like Flexeril, he may have drooling, vomiting, weakness, and acute anemias.

#3. How long does it take for a muscle relaxer to work on the dog?

Typically one to two hours.

The muscle relaxer will take almost 1 to 2 hours to affect the dog. However, its effect will be only for 8 hours. So most muscle relaxers are given all three times a day.

#4. How long do muscle relaxers last in a dog?

It may stay in the dog’s body for anywhere between six to eight hours.

Some muscle relaxers will start their effect after taking 30 minutes, and their effect will last for 4 to 6 hours.

A Few Final Words

Your dog may have muscle pain at some point in his life. If you don’t have a muscle relaxer for him, then you may think of giving Flexeril to your dog. 

If you give a 10 mg tablet to your 40-pound dog, it will not be poisonous to your furry friend. But he may have side effects like drooling and vomiting. But if you give a higher dosage of Flexeril(i.e., 218mg ) to your 40-pound dog, it can cause a toxic effect on your dog.

The best thing is to consult your veterinarian about your dog’s muscle pain. The doctor will do the necessary treatment accordingly. He may prescribe muscle relaxers in pill form to reduce muscle inflammation in your dog.

We thank you for reading this article. If you have any queries regarding muscle relaxers, you can write to us below and we will answer them for you. You might also like to read about other drugs such as Zzzquil and Benadryl.