1. Home > 
  2. Pages > 
  3. Pet Blog | EntirelyPets Blog > 
  4. Articles > 
  5. Gabapentin Side Effects

Gabapentin Side Effects

Gabapentin is an anti-seizure drug that has benefitted cats, dogs and horses in various ways. In addition to being an effective treatment for seizures, it can also be used to soothe neuropathic and chronic arthritis pains. This multifunctional medication can even be used in humans for similar purposes, though it is not recommended sharing this with pets as gabapentin intended for humans often contains xylitol, a chemical that is toxic to dogs and cats. This prescription medicine can be truly beneficial for many pets and is generally safe to use.

How it works

While it is safe to use, scientists do not completely understand how gabapentin works. Scientists believe that gabapentin binds to calcium channels on nerve cells in the central nervous system. This alters the release of certain neurotransmitters such as glutamate, which when released can cause surrounding nerve cells to become excited. By inhibiting glutamate, gabapentin can help manage electrical activity in the brain thus preventing partial and secondary seizures.

Gabapentin also plays a direct role in managing pain signals. When pain is caused by damaged or disrupted nerves, gabapentin can reduce the neurotransmitters released by damaged nerves. Many pet owners have seen profound improvements in their petís pain while on gabapentin. There are side effects that pet owners should look out for to ensure that gabapentin is the best choice for their pets.


The common side effects observed in cats are often mild. The main side effects cats can experience are weight gain, ataxia (clumsiness or stumbling) and lethargy. Diarrhea can result in some cases but is not as common as the other symptoms. Cats often develop a tolerance to gabapentin, meaning that the dose will need to be increased over time, as determined by your veterinarian. Gabapentin can be a very good option for cats especially when managing long term chronic pain.


Dogs exhibit very similar side effects to cats when taking gabapentin. Dogs can experience mild lethargy and loss of coordination (ataxia). If a dog has taken too much gabapentin, the side effects become much more severe: extreme lethargy or drowsiness, depression, and severe ataxia. Ask your vet which precautions you should take before administering gabapentin to your dog.


Gabapentin can be used to manage seizures in foals facing hypoxic ischemic encephalopathy, a brain injury due to asphyxia. Thus far, there have not been any reported negative side effects in horses, although testing is still underway to ensure that no negative side effects can occur. Research about equine uses of gabapentin are ongoing.

Other Considerations

Gabapentin should not be administered to pregnant or nursing cats and dogs as it has been associated with fetal loss. While gabapentin has been administered to pregnant horses, it is recommended that you discuss this with your vet prior to treatment. As with many other analgesics, gabapentin should not be used on animals that have lowered kidney or liver function. Additionally, gabapentin should not be administered in conjunction with antacids as they can make gabapentin less functional. Lastly, gabapentin should not be stopped abruptly, as this can cause seizures and pain. Pets should be weaned off gabapentin slowly.

We hope this article has helped you understand the side effects of gabapentin and that you will be able to make the most informed decision when managing your petís chronic pain.