How Does Gabapentin Work? 6 FAQs Answered

Gabapentin (Neurontin) is one of the most commonly used medications in the U.S. It’s FDA approved to treat seizures and nerve pain from shingles (postherpetic neuralgia). It also has several off-label uses.

If you’ve been prescribed gabapentin, you may wonder how it works and how long it takes to work. Here, we’ll answer these questions and more.

1. How does gabapentin work?

It’s not exactly clear how gabapentin works to treat various health conditions. But we know that gabapentin mimics a brain chemical called gamma-aminobutyric acid (GABA). GABA slows down, or quiets, brain and nerve activity. This is thought to relieve nerve pain, decrease anxiety, and prevent seizures — among other functions.

While mimicking GABA can have several positive effects, it can also cause side effects such as  drowsiness. People who have trouble sleeping may welcome drowsiness, but it can also make it more difficult to complete daily tasks. 

2. What does gabapentin do?

Gabapentin immediate-release (IR) is FDA approved to treat certain types of seizures and postherpetic neuralgia. It’s also used off-label for several conditions, such as alcohol use disorder, fibromyalgia, and anxiety. And it’s prescribed for other types of nerve pain, such as sciatica and nerve pain from diabetes.

Gabapentin is also available in two extended-release (ER) forms: Gralise and Horizant. Gralise is approved for postherpetic neuralgia. Horizant is approved for postherpetic neuralgia and restless leg syndrome.

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3. How long does gabapentin take to work?

It depends on what you’re treating. For example, you may feel the effects of gabapentin for nerve pain within a week of taking it. But it can take several weeks to see significant improvement. If you’re taking gabapentin for anxiety, full effects may also take several weeks.

It can take time to find the right gabapentin dose, which is why the medication might not be as effective at first. Gabapentin doses vary significantly from person to person. Most people start taking lower doses and then their dose is increased slowly to give their body time to adapt to gabapentin. Your healthcare professional will give you specific instructions if they want you to increase your dose.

If your symptoms don’t improve after a couple weeks of taking gabapentin, talk to your prescriber. They might consider increasing your dose. But don’t make any changes without talking to them first. Taking too much gabapentin can be dangerous.

4. Are there factors that can affect how long gabapentin takes to work?

Yes, several factors can affect how long it takes for gabapentin to work. They include:

• How quickly you reach your ideal dose: Your gabapentin dosage may be increased every few days. But if you have side effects from gabapentin, your prescriber may wait longer between dosage increases. This allows your body to get used to the medication. If your dose is increased more slowly, it may take longer to feel the medication’s full benefits.

• Other medications you take: Certain medications can interact with gabapentin, and some interactions may lead to lower levels of gabapentin in the body. For example, medications containing aluminum or magnesium can lower gabapentin absorption. Examples include magnesium oxide and Rolaids (calcium carbonate / magnesium hydroxide). It’s best to avoid taking gabapentin within 2 hours of taking these medications so gabapentin can achieve its full effect. 

• Foods you eat: Taking gabapentin with high-protein foods may increase the amount of gabapentin your body absorbs. This may also affect how quickly gabapentin starts to work. You can take gabapentin IR with or without food. But you should take Horizant and Gralise with food for maximum absorption.

5. What to expect when starting gabapentin

When you first start taking gabapentin, you may have some side effects. The most common gabapentin side effects are sleepiness and dizziness. Other possible risks include swelling and weight gain.

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• What gabapentin side effects should you watch for? Like all medications, gabapentin can have side effects. Common examples include drowsiness and dizziness.

• Is gabapentin a controlled substance? In some states, gabapentin is a controlled substance. That means there are restrictions on how it’s prescribed and refilled.

• Does gabapentin interact with other medications? Yes, gabapentin can interact with other medications such as opioids and benzodiazepines, as well as with alcohol.

Your prescriber may recommend that you take it at bedtime. This lowers your risk of being sleepy or dizzy during the day. However, it’s common to take gabapentin three times a day once you’ve reached your ideal dose. So try to avoid activities that require alertness when starting this medication or after your dose increases. Once you see how it affects you, you can determine whether it’s safe to resume these activities.

Additionally, you can reduce sleepiness and dizziness by avoiding other medications and substances that have the same side effects. These include benzodiazepines like alprazolam (Xanax), opioids like oxycodone (Roxicodone, Oxycontin), and alcohol.

6. How long should you take gabapentin?

It depends on why you’re taking gabapentin. You may need to continue it long term. Your healthcare professional will tell you how long you should take gabapentin.

For example, if you’re taking gabapentin to treat seizures, you may need to take it indefinitely. But you may be able to stop gabapentin if your nerve pain or restless leg syndrome symptoms improve.

It’s important to take gabapentin exactly as prescribed. Taking it incorrectly can increase your risk of drowsiness, dizziness, and more seriously, overdose. 

But don’t stop taking it abruptly (unless you're experiencing severe side effects, or your prescriber recommends it). Stopping gabapentin suddenly can increase your risk of having withdrawal symptoms, including anxiety, agitation, and seizures.

To help prevent withdrawal symptoms, your prescriber may gradually decrease your gabapentin dosage (called a medication taper). Your taper will depend on how long you were taking gabapentin and at what dose.

How to save on gabapentin

Gabapentin is available as both a brand-name and generic medication. There are a couple ways to save on it. 

• Save with GoodRx. GoodRx can help you save on the average retail price of generic gabapentin capsules. These may be as low as $7.20 at certain pharmacies with a free GoodRx coupon.

• Save with patient assistance programs. If you’re uninsured or underinsured, you may be eligible for Neurontin’s patient assistance program, which offers the medication for free.

You can also save on Gralise or Horizant. GoodRx can help you navigate between patient assistance programs and copay savings cards to save money on your prescription.

• Save with patient assistance programs. You may be eligible for Horizant’s patient assistance program, which offers the medication at a discount.

• Save with a copay savings card. If you have commercial insurance, you may be eligible to pay as little as $0 for Horizant and $20 for Gralise using a copay card from the manufacturer.

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Written by:

Rosanna Sutherby, PharmD

Rosanna Sutherby, PharmD, has been a community pharmacist in North Carolina for over 23 years. Before beginning her work as a medical writer, she held positions as a pharmacy manager, staff pharmacist, and immunizer.

Edited by:

Amy B. Gragnolati, PharmD, BCPS

Amy Gragnolati, PharmD, BCPS, is a pharmacy editor for GoodRx. Amy currently holds her pharmacist license in Georgia and California.

Reviewed by:

Ferras Bashqoy, PharmD, BCCCP, BCPPS

Ferras Bashqoy, PharmD, BCCCP, BCPPS, is a clinical pharmacotherapy specialist in the Neonatal Intensive Care Unit (NICU) at Hassenfeld Children’s Hospital in New York City. His favorite part of the job is working with preterm newborns because they are strong and mighty despite their size.

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