Gabapentin (Neurontin®, Horizant®)

OncoLink Team
Last Modified: January 8, 2016

Pronounced: GAB-a-PEN-tin
Classification: Anti-Convulsant

About Gabapentin

Gabapentin is in a class of medications called anti-convulsants, which means that it was originally developed to treat seizures. Gabapentin is still used to treat seizure disorders, but it is also often used to treat neuropathic pain. Neuropathic pain is pain that is related to injury or inflammation of nerves. If nerves are injured by trauma (including surgery and radiation), infection, nerve compression by tumor, or chemotherapy damage, gabapentin can often help to relieve the associated pain. No one knows the exact mechanism by which gabapentin treats neuropathic pain, but it may be related to how nerves send their pain signals to the brain.

How to Take Gabapentin

Gabapentin comes as a capsule, a tablet, an extended-release (long-acting) tablet, and an oral solution (liquid) to take by mouth with water. Capsules and tablets should be taken whole; do not chew, break or open. The medication is often prescribed 3x a day and should be taken at evenly spaced times throughout the day and night. If you are taking the extended release version, follow the directions given by your healthcare provider and take the medication with food.

This medication can interact with opioid pain medications; be sure to tell you healthcare provider about all medications and supplements you are using. The levels of this medication are affected by Maalox® (antacid). Gabapentin should be taken at least 2 hours after taking Maalox. You should not drink alcohol, in particular with the extended release formula as this affects how it is released.

Storage and Handling

Store this medication at room temperature in the original container. If you prefer to use a pillbox, discuss this with your oncology pharmacist. Ask your oncology team where to return any unused medication for disposal. Do not flush down the toilet or throw in the trash.

Where do I get this medication?

Gabapentin is available through retail and mail order pharmacies. Your oncology team will work with your prescription drug plan to identify an in-network pharmacy for medication distribution. 

Insurance Information

This medication may be covered under your prescription drug plan. Patient assistance may be available to qualifying individuals without prescription drug coverage. Co-pay cards, which reduce the patient co-pay responsibility for eligible commercially (non-government sponsored) insured patients, may also be available. Your care team can help you find these resources, if they are available.

Possible Side Effects of Gabapentin

There are a number of things you can do to manage the side effects of gabapentin. Talk to your doctor or nurse about these recommendations. They can help you decide what will work best for you. These are some of the most common side effects:

Sleepiness (Somnolence)

Feeling sleepy, drowsy or lightheaded may accompany the use of gabapentin. Some people just don't "feel like themselves" on this medication. Avoid driving or any other potentially dangerous tasks that require your concentration and a clear head until you know how the medication will affect you. Avoid alcohol or other sedatives while using gabapentin unless they are specifically prescribed by your doctor.

Allergic Reaction

This medication can cause an allergic reaction call DRESS (drug reaction with eosinophilia and systemic symptoms) and multi-organ hypersensitivity. Reports any signs and symptoms of allergic reaction, including rash, fever, or swollen lymph nodes (swollen glands) to your healthcare team immediately.

Suicidal Behavior/Ideation

Gabapentin may increase your risk for suicidal thoughts and behaviors. Your caregiver should be aware of this concern as well. Report any changes or worsening of mood or behavior or suicidal (self harm) thoughts to your healthcare team immediately.

Reproductive Concerns

Exposure of an unborn child to this medication could cause birth defects, so you should not become pregnant while on this medication. If you are pregnant or become pregnant, discuss the risks and benefits to continuing this medication with your care provider. You should consult with your healthcare team before breastfeeding while receiving this medication.


If someone intentionally or accidentally takes way too much Neurontin, they may experience double vision, slurred speech, drowsiness or diarrhea. This happens very rarely. If you suspect that you or someone you know has taken an overdose of Neurontin, call 911 immediately. Overdose of Neurontin is an emergency situation and needs immediate attention.



Click on any of these terms for more related articles

From the National Cancer Institute