An Overview of Gabapentin

In the quest to find effective preventive migraine treatments, healthcare providers sometimes prescribe medications "off-label." In these cases, a drug has been approved by the U.S. Food and Drug Administration (FDA) for one disorder, but has been found to have positive effects on an unrelated one.

Gabapentin is one such drug. It's an anti-seizure drug sometimes used to prevent migraines, though there is conflicting scientific evidence supporting its effectiveness in this regard.

In the United States, gabapentin is sold in generic form and under the brand names Neurontin, Gralise, Horizant, and Neuraptine.

How It Works

The precise mechanism of gabapentin’s action is not well known. Even though this drug has a similar structure to a brain neurotransmitter called GABA (gamma-aminobutyric acid), it has no effect on its receptors. It is believed that gabapentin blocks calcium channels, modulating the release of excitatory neurotransmitters.

Uses

Gabapentin is primarily used to treat epilepsy in people older than 12 and partial seizures in children ages 3 to 12. It is also FDA-approved to treat a condition called postherpetic neuralgia—the nerve-related pain complication of a herpes zoster attack (shingles) that can occur in adults.

Besides these uses, gabapentin is used off-label for a variety of other conditions like migraine prevention, as well as diabetic neuropathy, restless legs syndrome, and fibromyalgia.

Because of its benefit in treating these and other issues, gabapentin is what's known as an adjuvant analgesic—a drug that can help control pain, despite it not being primarily intended to do so. Gabapentin may be used alone or with other medications when necessary.

It's important to note, however, that The American Academy of Neurology (AAN) and the American Headache Society (AHS) do not list gabapentin as "effective" or "probably effective" for preventing migraines in their 2012 guidelines. Instead, gabapentin is given a level U rating, which means the evidence is conflicting or inadequate to support or refute its use for migraine prevention.

Formulation and Dosing

Gabapentin is taken by mouth and available as a capsule, tablet, or liquid. Dosages range from 300 to 3600 mg a day, though they are often adjusted for children, elderly people, and those with kidney disease.

The medication is available as an immediate-release oral tablet, an extended-release oral tablet, and an oral solution. It can be taken with or without food.

If you forget to take your dose, take it as soon as you remember. Never try to catch up by taking two capsules at once. Never stop taking gabapentin without your healthcare provider's OK. You will need to wean yourself off it slowly in order to avoid potentially serious side effects. 

Potential Side Effects

Like all drugs, gabapentin does have potential adverse effects, with the most common ones being dizziness and drowsiness. Less common but serious side effects include:

• Loss of coordination
• Blurred/double vision
• Unusual eye movements (nystagmus) or shaking (tremor) 
• Swelling of the hands, ankles, or feet

Tell your healthcare provider right away if any of these side effects occur.

A small number of people who take anticonvulsants for any condition may experience depression, suicidal thoughts/attempts, or other mental/mood problems. Tell your healthcare provider right away if you or a loved one notice any unusual or sudden changes in your mood, thoughts, or behavior including signs of depression, suicidal thoughts, or thoughts about harming yourself.

A very serious allergic reaction to gabapentin is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including fever, swollen lymph nodes, rash, itching/swelling (especially of the face, tongue, or throat), severe dizziness, or trouble breathing.

Interactions

Drinking alcohol may make some side effects of gabapentin more severe. 

Types of drugs that are known to interact with gabapentin and may cause problems include:

• Opiate pain medications, including Vicodin (hydrocodone) and morphine, among others
• Naproxen (Aleve, Naprosyn, and others)
• Medications used for heartburn, including Mylanta, Maalox, and cimetidine

If you do dipstick tests to check your urine for protein, tell your healthcare provider. Gabapentin may affect the results.

Your healthcare provider can advise you on whether you should avoid taking certain drugs with gabapentin entirely, or if the timing or dosage simply need to be adjusted.

Contraindications

Currently, there is not enough research or well-controlled studies on humans to deem this medication safe for expecting mothers.  Contact your healthcare provider to discuss whether the benefits of use may outweigh the risks in your case.

Gababentin should be avoided by people with chronic kidney disease or myasthenia gravis.

A Word From Verywell

Due to the lack of robust scientific findings, gabapentin is not likely to be a healthcare provider's first choice (or even second choice) when choosing a preventive medication for migraines.

If you are currently taking gabapentin for migraine prevention, and it's working for you, then you may be one of the fortunate ones. Keep in mind, guidelines are based on statistics from large populations and cannot predict any one person's response.