1. Gabapentin oral capsule is available as both a generic and brand-name drug. Brand name: Neurontin.
  2. Gabapentin is also available as an immediate-release oral tablet, an extended-release oral tablet, and an oral solution.
  3. Gabapentin oral capsule is used to treat partial seizures in adults and children. It’s also used to treat nerve pain caused by a shingles infection.

Gabapentin is a prescription drug. It comes as an oral capsule, an immediate-release oral tablet, an extended-release oral tablet, and an oral solution.

Gabapentin oral capsule is available as the brand-name drug Neurontin. It’s also available as a generic drug. Generic drugs usually cost less than the brand-name version. In some cases, the brand-name drug and the generic version may be available in different forms and strengths.

Why it’s used

Gabapentin oral capsule is used to treat the following conditions:

  • Seizures: Gabapentin is used to treat partial (focal) seizures. It’s taken together with other seizure medications in adults and in children 3 years of age and older who have epilepsy.
  • Postherpetic neuralgia: This is pain from nerve damage caused by shingles, a painful rash that affects adults. Shingles appears after infection with the varicella zoster virus. This virus occurs in people who have had chicken pox.

Gabapentin may be used as part of a combination therapy. This means you may need to take it with other drugs.

How it works

Gabapentin belongs to a class of drugs called anticonvulsants. A class of drugs is a group of medications that work in a similar way. These drugs are often used to treat similar conditions.

It’s not fully understood how gabapentin works. For postherpetic neuralgia, it seems to prevent the increase in sensitivity to pain that occurs. For seizures, it may alter the effect of calcium (low levels of calcium may cause seizures).

Gabapentin oral capsule causes dizziness and drowsiness. Avoid driving or using heavy machinery while taking this drug until you know how it affects you.

Gabapentin oral capsule can cause mild or serious side effects. The following list contains some of the key side effects that may occur while taking gabapentin. This list does not include all possible side effects.

For more information on the possible side effects of gabapentin, or tips on how to deal with a troubling side effect, talk with your doctor or pharmacist.

More common side effects

Some of the more common side effects that can occur with use of gabapentin are listed below, along with their rates:

Also:

  • viral infection
  • fever
  • nausea and vomiting
  • trouble speaking
  • hostility
  • jerky movements

The side effect rates are based on patients over 12 years old, as reported in clinical trials for the brand equivalent, Neurontin. Certain rates vary by age. For example, pediatric patients 3 to 12 years of age most commonly experienced viral infection (11%), fever (10%), nausea and/or vomiting (8), tiredness (8%), and hostility (8%). There were no clinically significant differences in rates between men and women. For more information, see the FDA package insert.

If these effects are mild, they may go away within a few days or a couple of weeks. If they’re more severe or don’t go away, talk to your doctor or pharmacist.

Serious side effects

Call your doctor right away if you have serious side effects. Call 911 if your symptoms feel life-threatening or if you think you’re having a medical emergency. Serious side effects and their symptoms can include the following:

  • Changes in mood or anxiety. Symptoms can include:
    • thoughts of suicide or dying
    • attempts to commit suicide
    • anxiety that’s new or gets worse
    • crankiness that’s new or gets worse
    • restlessness
    • panic attacks
    • trouble sleeping
    • anger
    • aggressive or violent behavior
    • extreme increase in activity and talking
    • unusual changes in behavior or mood
  • Changes in behavior and thinking, especially in children ages 3 to 12 years. Symptoms can include:
    • emotional changes
    • aggressiveness
    • trouble concentrating
    • restlessness
    • changes in school performance
    • hyper behavior
  • Serious and life-threatening allergic reaction. Symptoms can include:
    • skin rashes
    • hives
    • fever
    • swollen glands that do not go away
    • swollen lips and tongue
    • yellowing of your skin or the whites of your eyes
    • unusual bruising or bleeding
    • severe tiredness or weakness
    • unexpected muscle pain
    • frequent infections

Gabapentin oral capsule can interact with several other medications. Different interactions can cause different effects. For instance, some can interfere with how well a drug works, while others can cause increased side effects.

Below is a list of medications that can interact with gabapentin. This list does not contain all drugs that may interact with gabapentin.

Before taking gabapentin, be sure to tell your doctor and pharmacist about all prescription, over-the-counter, and other drugs you take. Also tell them about any vitamins, herbs, and supplements you use. Sharing this information can help you avoid potential interactions.

If you have questions about drug interactions that may affect you, ask your doctor or pharmacist.

Pain drugs

When used with gabapentin, certain pain drugs can increase its side effects, such as tiredness. Examples of these drugs include:

  • morphine

Stomach acid drugs

When used with gabapentin, certain drugs used to treat stomach acid problems can reduce the amount of gabapentin in your body. This can make it less effective. Taking gabapentin 2 hours after taking these drugs can help prevent this problem. Examples of these drugs include:

  • aluminum hydroxide
  • magnesium hydroxide

The gabapentin dosage your doctor prescribes will depend on several factors. These include:

  • the type and severity of the condition you’re using gabapentin to treat
  • your age
  • the form of gabapentin you take
  • other medical conditions you may have

Typically, your doctor will start you on a low dosage and adjust it over time to reach the dosage that’s right for you. They’ll ultimately prescribe the smallest dosage that provides the desired effect.

The following information describes dosages that are commonly used or recommended. However, be sure to take the dosage your doctor prescribes for you. Your doctor will determine the best dosage to suit your needs.

Forms and strengths

Generic: Gabapentin

  • Form: oral capsule
  • Strengths: 100 mg, 300 mg, 400 mg

Brand: Neurontin

  • Form: oral capsule
  • Strengths: 100 mg, 300 mg, 400 mg

Dosage for postherpetic neuralgia

Adult dosage (ages 18–64 years)

  • Typical starting dosage: Day 1, 300 mg; day 2, 600 mg (300 mg two times per day, spaced evenly throughout the day); day 3, 900 mg (300 mg, three times per day, spaced evenly throughout the day). Your doctor may further increase your dosage after day 3.
  • Maximum dosage: 1,800 mg per day (600 mg, three times per day, spaced evenly throughout the day)

Child dosage (ages 0–17 years)

Dosage for people younger than 18 years has not been established.

Senior dosage (ages 65 years and older)

Your kidney function may decrease with age. Your body may get rid of this drug more slowly. Your doctor may start you on a lower dose so that too much of this drug does not build up in your body. Too much of the drug in your body can be dangerous. Your doctor may change your dose based on how well your kidneys are working.

Dosage for partial-onset seizures

Adult dosage (ages 18–64 years)

Typical starting dosage: 900 mg per day (300 mg, three times per day, spaced evenly throughout the day). Your doctor may increase your dose to 2,400–3,600 mg per day.

Child dosage (ages 12–17 years)

Typical starting dosage: 300 mg, three times per day, spaced evenly throughout the day. This can increase to 2,400–3,600 mg per day.

Child dosage (ages 3–11 years)

Typical starting dosage: 10–15 mg/kg/day, divided into three doses, spaced evenly throughout the day. Your child’s doctor may increase the dosage to meet your child’s needs.

Maximum dosage: 50 mg/kg/day.

Child dosage (ages 0–2 years)

Dosage for people younger than 3 years has not been established.

Senior dosage (ages 65 years and older)

Your kidney function may decrease with age. Your body may get rid of this drug more slowly. Your doctor may start you on a lower dose so that too much of this drug does not build up in your body. Too much of the drug in your body can be dangerous. Your doctor may change your dose based on how well your kidneys are working.

Special considerations

Kidney problems: If you are older than 12 years and have kidney problems or are on hemodialysis, your dose of gabapentin will need to be changed. This will be based on how well your kidneys are working.

Gabapentin oral capsule comes with several warnings. Call your doctor if you start having more seizures or a different kind of seizure while taking this drug.

Drowsiness warning

Gabapentin can slow your thinking and motor skills and cause drowsiness and dizziness. It’s not known how long these effects last. You should not drive or use heavy machinery while taking this drug until you know how it affects you.

Depression warning

Using this drug increases your risk of suicidal thoughts and behavior. Talk to your doctor if you feel depressed or notice any changes in your mood or behavior. Also talk to your doctor if you are having thoughts of harming yourself, including suicide.

Multiorgan hypersensitivity/DRESS warning

This medication can cause multiorgan hypersensitivity. This is also known as a drug reaction with eosinophilia and systemic symptoms (DRESS). This syndrome can be life-threatening. Call your doctor right away if you have symptoms such as a rash, a fever, or swollen lymph nodes.

Allergy warning

Gabapentin can cause a severe allergic reaction. Symptoms can include:

  • trouble breathing
  • swelling of your throat or tongue
  • hives
  • rash

Don’t take this drug again if you have ever had an allergic reaction to it before. Taking it a second time after any allergic reaction to it could be fatal (cause death).

Alcohol interaction warning

Avoid drinking alcohol while taking gabapentin. Gabapentin can cause sleepiness, and drinking alcohol can make you even more sleepy. Alcohol can also make you more likely to feel dizzy and have trouble concentrating.

Warnings for people with certain health conditions

For people with epilepsy: Don’t stop taking gabapentin suddenly. Doing this can increase your risk of having a condition called status epilepticus. This is a medical emergency during which short or long seizures occur for 30 minutes or more.

Gabapentin can cause problems in children aged 3–12 years who have epilepsy. It raises their risk of thought problems as well as behavioral problems, such as being hyper and acting hostile or restless.

For people with kidney problems: Your body processes this drug more slowly than normal. This may cause the drug to increase to dangerous levels in your body. Talk to your doctor about whether this drug is safe for you.

Warnings for other groups

For pregnant women: The use of gabapentin has not been studied in humans during pregnancy. Research in animals has shown negative effects to the fetus when the mother takes the drug. However, animal studies don’t always predict the way humans would respond.

Talk to your doctor if you’re pregnant or planning to become pregnant. This drug should only be used if the potential benefit justifies the potential risk to the fetus. Call your doctor if you become pregnant while taking this drug.

If your doctor prescribes gabapentin for you while you’re pregnant, ask about the NAAED Pregnancy Registry. This registry tracks the effects of anti-seizure drugs on pregnancy. Information can be found at aedpregnancyregistry.org.

For women who are breastfeeding: Gabapentin may pass into breast milk and cause serious side effects in a breastfeeding child. Tell your doctor if you are breastfeeding. You should decide together if you should stop taking this drug or stop breastfeeding.

For seniors: Kidney function may decrease with age. You may process this drug more slowly than younger people. Your doctor may start you on a lowered dose so that too much of this drug does not build up in your body. Too much of the drug in your body can be dangerous.

For children: Gabapentin has not been studied in children for the management of postherpetic neuralgia. It should not be used in people younger than 18 years. This drug should not be used to treat partial seizures in children younger than 3 years.

Suicide prevention

  • If you think someone is at immediate risk of self-harm or hurting another person:
  • •  Call 911 or your local emergency number.
  • •  Stay with the person until help arrives.
  • •  Remove any guns, knives, medications, or other things that may cause harm.
  • •  Listen, but don’t judge, argue, threaten, or yell.
  • If you or someone you know is considering suicide, get help from a crisis or suicide prevention hotline. Try the National Suicide Prevention Lifeline at 800-273-8255.

Gabapentin oral capsule is used for short-term or long-term treatment. The length of treatment depends on what condition it’s being used to treat. It comes with serious risks if you don’t take it as prescribed.

If you stop taking it suddenly or don’t take it at all:

  • For seizures: This can increase your risk of status epilepticus, which is a medical emergency. With this condition, short or long seizures occur for 30 minutes or more. If your doctor decides to reduce your dose or have you stop taking gabapentin, they will do this slowly. Your dose will be reduced or your treatment stopped over the course of at least one week.
  • For postherpetic neuralgia: Your symptoms won’t improve.

If you miss doses or don’t take it on schedule: Your medication may not work as well or may stop working completely. In order for this drug to work well, a certain amount needs to be in your body at all times.

If you take too much: You could have dangerous levels of the drug in your body. Symptoms of an overdose of this drug can include:

  • double vision
  • slurred speech
  • tiredness
  • loose stools

If you think you’ve taken too much of this drug, call your doctor or local poison control center. If your symptoms are severe, call 911 or go to the nearest emergency room right away.

What to do if you miss a dose: If you forget to take your dose, take it as soon as you remember. If you remember just a few hours before the time for your next dose, then only take one dose. Never try to catch up by taking two capsules at once. This could result in dangerous side effects.

How to tell if the drug is working: You should have fewer seizures. Or you should have less nerve pain.

Keep these considerations in mind if your doctor prescribes gabapentin oral capsule for you.

General

Gabapentin oral capsules can be taken with or without food. Taking them with food can help to reduce upset stomach.

Storage

  • Store gabapentin at room temperature between 68°F and 77°F (20°C and 25°C).
  • Don’t store this medication in moist or damp areas, such as bathrooms.

Refills

A prescription for this medication is refillable. You should not need a new prescription for this medication to be refilled. Your doctor will write the number of refills authorized on your prescription.

Travel

When traveling with your medication:

  • Always carry your medication with you, such as in your carry-on bag.
  • Don’t worry about airport X-ray machines. They can’t hurt your medication.
  • You may need to show airport staff the pharmacy label for your medication. Be sure to carry with you the prescription-labeled box that your medication came in.
  • Do not put this medication in your car’s glove compartment or leave it in the car. Be sure to avoid doing this when the weather is very hot or very cold.

Clinical monitoring

Your doctor will monitor your kidney function.

Insurance

Many insurance companies require a prior authorization for gabapentin. This means your doctor will need to get approval from your insurance company before your insurance company will pay for the prescription.

There are other drugs available to treat your condition. Some may be better suited for you than others. Talk to your doctor about other drug options that may work for you.

Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up-to-date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or other healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.