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 may interact with other medications

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.

Gabapentin 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.