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3 Most Common Side Effects of Gabapentin 

Author: Liza Kahn, DVM

As pet parents, we want to be familiar and comfortable with the medications used to treat our furry family members.

As a vet, I can assure you that gabapentin is the right choice for many dogs and cats.

With a wide safety margin, minimal side effects, and multiple different uses, it is no wonder that this medication has gained popularity in recent years.

Your dog may be prescribed gabapentin to help manage pain and keep them calm after surgery, as part of a treatment plan for conditions such as arthritis or seizures, or as a way to help decrease anxiety.

Let’s take a closer look at how this medication works, why your veterinarian may recommend it, and the most common side effects. 

What is Gabapentin? 

Gabapentin is classified as an analgesic (pain reliever) and anticonvulsant (anti-seizure medication).

It is most frequently used to manage pain, seizures, and anxiety in dogs.

This medication works by altering the activity of neurotransmitters in the brain, which are responsible for communicating messages between nerve cells. 

Originally Developed for Human Use

It was initially a human drug and is used in human medicine (often for treatment of epilepsy or pain associated with nerve damage from conditions such as diabetic neuropathy or post-herpetic neuralgia).

It is marketed under several brand names, including Neurontin, Aclonium, Equipax, Gantin, Gabarone, Gralise, Nuerostil, and Progresse.

In fact, the use of gabapentin in veterinary patients is considered “off-label”, meaning it is not FDA-approved. However, as long as you follow your veterinarian’s instructions, this medication is extremely safe and well-tolerated in dogs and cats.

Gabapentin is a prescription medication, meaning you will require a vet visit to obtain it. In some states, gabapentin is also considered a controlled substance. 

How Does Gabapentin Work (Mechanism of Action)? 

Absorption of gabapentin occurs in the small intestine. It is then partially metabolized by the liver and excreted by the kidneys.

For this reason it should be used with care in animals with kidney or liver disease. Gabapentin is a short-acting drug, with peak effects seen one to two hours after administration and not lasting more than 24 hours. It has a short half-life of two to four hours.  

Gabapentin works in several different ways to treat pain, seizures, and anxiety, although the exact mechanism of action isn’t well understood. While gabapentin has a structure similar to the inhibitory neurotransmitter gamma-aminobutyric acid

(GABA), this is not related to it’s primary mechanism of action. Instead, gabapentin acts in the following ways:  

  • Gabapentin relieves pain by binding to voltage-sensitive calcium channels which are upregulated when neurons are stimulated in response to stress or injury. This leads to a decrease in the release of excitatory neurotransmitters. 
  • The mechanism by which gabapentin helps control seizures and anxiety is not fully understood. 
Gabapentin is used to treat pain, seizures, and anxiety in dogs.

Why Vets Prescribe Gabapentin

Gabapentin is used frequently in veterinary medicine for a variety of purposes. 

Pain Relief

Gabapentin is most commonly used for pain management. There are multiple different types of pain that dogs can experience and that gabapentin may help manage.

It’s especially helpful in managing neuropathic pain associated with nerve or central nervous system damage. It is also commonly used at the same time as other types of pain medications and therapies for a multimodal approach to a variety of medical conditions. 

Neuropathic pain

Neuropathic pain is pain caused by the nervous system. Injury or disease affecting nerves, the spinal cord, or the brain can affect how pain signals are sent and interpreted.

This can cause animals to have an exaggerated pain response to stimuli that should not normally be painful (allodynia) or only cause minor discomfort (hyperesthesia).

In people, nerve pain is commonly described as a “pins and needles sensation”, burning, or tingling. Examples of neuropathic pain in animals include hyperesthesia syndrome in cats and syringomyelia in Cavalier King Charles Spaniels.

Chronic pain 

Dogs with arthritis, intervertebral disc disease, cancer, and other ailments may suffer from chronic pain.

The constant presence of inflammation or injury can lead to excessive pain signals in the brain, and can significantly affect quality of life. This is a common occurrence, with arthritis pain affecting approximately 40% of dogs.

To treat this type of pain gabapentin is often combined with other pain medications, such as nonsteroidal anti-inflammatory drugs (NSAIDs) and tramadol. Other types of therapy such as acupuncture, supplements, and physical therapy may also be beneficial in helping keep these dogs comfortable. 

Post-operative pain management

Gabapentin is an excellent choice for post operative pain, along with other pain medications such as NSAIDs and opioids.

Just like people, dogs need to take it easy after surgery, often for two weeks or longer depending on the type of surgery.

Not only can gabapentin contribute to pain relief, but the sedating effects are beneficial in keeping dogs calm and quiet after surgery. Gabapentin may also be helpful in managing other types of acute pain. 

Signs of pain in dogs

Animals are experts at hiding pain and illness; therefore it is not always easy to tell if your furry family member is in pain.

As dog parents, you know your pup best and may be able to pick up on subtle cues or changes in behavior or daily routine. Here is a guide to help identify signs of pain in your dog. 

Common signs of pain in dogs include the following:

  • Sudden anxiety
  • Hiding
  • Tail between the legs
  • Wide eye (whale eye)
  • Tongue lagging or hanging out
  • Panting
  • Arched back
  • Vocalizing (whining, barking)
  • Change in personality or behavior
  • Suddenly wants to be at your side or suddenly wants to hide

Keep in mind that dogs in pain may exhibit some or all of the signs noted above.

Behavioral issues such as anxiety

Anxiety disorders are common in dogs. Just like in people, anxiety may be situational (caused by a specific event, such as thunderstorms), or more generalized, affecting your dog’s daily life.

Vets and veterinary behaviorists often recommend a multimodal approach for managing anxiety, including medications, changes that you can make to the environment, and a training or behavioral modification program. 

Gabapentin is commonly used in cats to help manage stress and anxiety associated with specific events, such as veterinary visits or travel.

It can also be used in dogs for situational anxiety or long-term management of anxiety in conjunction with other behavioral medications and training.

Gabapentin is not generally used alone to treat canine anxiety. Is often used with trazodone for situational anxiety or with long-acting SSRIs (such as Prozac) for generalized anxiety. 


Gabapentin can be used to help manage seizures in dogs.

It is often used in combination with other anticonvulsant or antiepileptic drugs to help better control seizures and improve quality of life. The mechanism by which gabapentin helps prevent seizures in dogs is not known.

It is also important not to stop this medication abruptly, as it may lead to an increase in seizures. 

Can Gabapentin Be Used With Other Medications? 

Gabapentin is frequently used as an adjunctive therapy by combining it with other medications.

It has a synergistic effect with some medications, such as tramadol, in which the medications help each other to work more effectively.

Combining medications in this way also allows your vet to approach their health problems from different angles and to use lower doses of medication, meaning fewer side effects for your pup. 

There are a couple of drug interactions to be aware of.

For example, certain medications like antacids should not be given at the same time as gabapentin, as they can reduce its absorption. Care should also be taken with other medications that may cause sedation. 

Dosing Guidelines

Your vet will determine a proper dosage of gabapentin for your dog based on their weight, underlying medical condition(s), and what other medications they may be taking. 

Formulations of gabapentin

Gabapentin is available in several forms and strengths.

  • 100, 300, and 400 mg capsules – This is generally the most common formulation used in veterinary medicine. 
  • A liquid formulation for humans – This oral solution should not be used as it contains the artificial sweetener xylitol, which is extremely toxic to dogs and causes a severe drop in blood sugar.  
  • 300, 600, and 800 mg tablets
  • 300 and 600 mg extended-release tablets 
  • Additional strengths and pet-friendly flavors may be obtained through a compounding pharmacy. 

Common dosages for dogs 

While you may have gabapentin in your medicine cabinet, it is important not to give this medication to your dog without first discussing it with your vet and establishing an appropriate dosage.

While gabapentin is generally very safe, it should always be used under the guidance of a veterinarian.

They will take into account your dog’s weight, underlying medical condition, and any other medications that they may be taking. For this reason, the appropriate dose of gabapentin for each dog may vary widely. 

Gabapentin is generally given at a range of 5 to 30 mg/kg up to three times a day. For situational anxiety, it is usually given two hours before a stressful event.

Higher doses may be used for seizure control, although it may be best to start at a lower dosage and gradually increase it.

Some dogs may develop a tolerance to gabapentin, meaning that in order to remain effective, the dosage must be increased over time. 

How to administer gabapentin for dogs

Gabapentin is generally given by mouth up to three times per day (every eight hours).

It can be given with food or on an empty stomach. While many dogs are not picky, others may prefer that you hide the pill in a pill pocket, peanut butter, or other treats.

If your gabapentin is in the form of a capsule, it is ok to open it and mix the powder with canned food; however, extended-release products should never be crushed or opened.

Gabapentin can be stored at room temperature and should be kept out of reach of children. 

In the case of a missed dose of gabapentin, check with your veterinarian for their recommendations.

Generally it is ok to give the medication when you remember, unless it is close to the next scheduled dose, in which case it should just be skipped. 

Side effects of gabapentin in dogs

3 Most Common Side Effects of Gabapentin

Like any medication, gabapentin can cause side effects in some dogs. In general, this medication is extremely safe and well-tolerated.

The most common side effect seen is mild sedation, and in many cases, this is part of the desired effect.

If side effects are too bothersome, your veterinarian may recommend decreasing the dosage. Starting at a lower dose and gradually increasing over time may also help diminish side effects.

Possible side effects include: 

1. Sedation

Gabapentin can make dogs sleepy or lethargic. In many cases this is beneficial, for example in keeping a dog calm and quiet after surgery.

The amount of sedation seen may vary on the dosage, the individual dog, and other medications that they may be taking at the same time. 

2. Ataxia

Some dogs may appear wobbly, weak, or experience a loss of coordination, especially in the hind legs. This might happen the first time your dog is administered gabapentin, but not the next time.

It’s a good idea for dog parents to keep a watchful eye on dogs taking gabapentin for the first time.

3. Gastrointestinal upset

For example, nausea, vomiting, decreased appetite, or diarrhea. 

Rare Side Effects of Gabapentin in Dogs

Serious side effects are rare, however, it is possible for a dog to have an allergic reaction to this medication.

Signs of a serious allergic reaction in dogs include:

  • Swelling around the face
  • Hives
  • Itchy skin
  • Changes in breathing (wheezing)
  • Depression
  • Vomiting
  • Diarrhea
  • Loss of appetite
  • Changes in urinary habits
  • Abnormal bleeding

Note: Anaphylactic reactions usually occur within one hour of taking medication. If you believe your dog is having an anaphylactic reaction, contact an emergency veterinary clinic ASAP.

Gabapentin vs Underlying Health Conditions in Dogs

Gabapentin should be used with caution or at lower doses in animals with decreased renal function (kidney disease) and liver disease.

Gabapentin can also cause a false positive on a urine dipstick test for protein in the urine.

If this medication is stopped abruptly after long-term use, it can lead to withdrawal seizures. Therefore it is best to taper slowly over a couple of weeks. 

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Can a Dog Overdose on Gabapentin?

Gabapentin has a wide safety margin, meaning even high doses of gabapentin are generally safe. It is possible to give your dog too much gabapentin. However, serious complications are unlikely.

Signs that your dog has had too much gabapentin include:

  • Decreased energy (lethargy)
  • Vomiting
  • Diarrhea
  • Lack of coordination
  • Extreme sedation (it might be harder to get your dog to wake up or your dog might not be able to stay awake for very long)

Depending on the amount ingested and how promptly the overdose is recognized, veterinary treatment such as inducing vomiting and administration of activated charcoal to prevent further absorption may be indicated.

In case of accidental overdose you should call your veterinarian, animal poison control (888) 426-4435, or the pet poison hotline (855) 764-7661. 

What Should I Do If I Missed a Dose of Gabapentin?

You can give your dog his or her gabapentin dosage when you remember, as long as it’s not too close to the next scheduled dose.

The best advice here is to call the veterinary office and ask.


Although gabapentin is prescribed for use in animals, it’s actually a prescription medication designed for human use.

Dogs with arthritis, cancer, seizures, or nerve pain may benefit from gabapentin. In addition to pain relief, gabapentin can also be used to treat seizures in dogs.

Many dogs are afraid of thunder, fireworks, or other loud noises.

Long car rides or travel in general can also cause your dog a lot of stress. In cases like this, gabapentin might be the answer. It works great as a sedative to help your pooch get through life’s tougher moments.

Gabapentin is safe for dogs when prescribed by a veterinarian.

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