Generic name: gabapentin [ GA-ba-PEN-tin ]
Brand names: Gralise, Horizant, Neurontin, Gabarone
Drug class: Gamma-aminobutyric acid analogs

Medically reviewed by Melisa Puckey, BPharm. Last updated on May 23, 2022.

What is gabapentin?

Gabapentin (Neurontin, Gralise, Horizant) is a medicine used to treat partial seizures, nerve pain from shingles and restless leg syndrome. It works on the chemical messengers in your brain and nerves.  Gabapentin is from a group of medicines called anticonvulsants. 

Different brands of gabapentin are not interchangeable and they are FDA approved for different conditions. Use only the brand and form of gabapentin your doctor has prescribed. Check your medicine each time you get a refill to make sure you receive the correct form. 

Neurontin (gabapentin) is used to treat pain you may have from shingles (postherpetic nerve pain). It is also used with other seizure medicines for partial onset seizures in patients 3 years and older.

Gralise (gabapentin) is only used for pain after having shingles (postherpetic nerve pain). It should not be used for any other medical condition.

Horizant (gabapentin enacarbil) is an extended release tablet used to treat restless legs syndrome and for the pain from having shingles (postherpetic nerve pain).

Generic brands of gabapentin capsules, USP are used for postherpetic nerve pain and for add on therapy for partial onset seizures in patients 3 years and older

Warnings

Gabapentin can cause life-threatening breathing problems, especially if you already have a breathing disorder or if you use other medicines that can make you drowsy or slow your breathing. Seek emergency medical attention if you have very slow breathing.

Some people have thoughts about suicide or behavior changes while taking gabapentin. Stay alert to changes in your mood or symptoms. Report any new or worsening symptoms to your doctor.

Avoid driving or hazardous activity until you know how gabapentin will affect you. Dizziness or drowsiness can cause falls, accidents, or severe injuries.

Do not stop using gabapentin suddenly, even if you feel fine.

Before taking this medicine

You should not use gabapentin if you are allergic to it.

To make sure gabapentin is safe for you, tell your doctor if you have ever had:

• breathing problems or lung disease, such as chronic obstructive pulmonary disease (COPD);

• kidney disease (or if you are on dialysis);

• diabetes;

• depression, a mood disorder, or suicidal thoughts or actions;

• a drug addiction;

• a seizure (unless you take gabapentin to treat seizures);

• liver disease;

• heart disease; or

• (for patients with RLS) if you are a day sleeper or work a night shift.

Some people have thoughts about suicide while taking this medicine. Children taking gabapentin may have behavior changes. Stay alert to changes in your mood or symptoms. Report any new or worsening symptoms to your doctor.

It is not known whether this medicine will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant.

Seizure control is very important during pregnancy, and having a seizure could harm both mother and baby. Do not start or stop taking gabapentin for seizures without your doctor's advice, and tell your doctor right away if you become pregnant.

If you are pregnant, your name may be listed on a pregnancy registry to track the effects of gabapentin on the baby.

It may not be safe to breastfeed while using this medicine. Ask your doctor about any risk.

How should I take gabapentin?

Take gabapentin exactly as prescribed by your doctor. Follow all directions on your prescription label. Do not take in larger or smaller amounts or for longer than recommended.

If your doctor changes your brand, strength, or type of gabapentin, your dosage needs may change. Ask your pharmacist if you have any questions about the new kind of gabapentin you receive at the pharmacy.

Both Gralise and Horizant should be taken with food.

Neurontin can be taken with or without food.

If you break a Neurontin tablet and take only half of it, take the other half at your next dose. Any tablet that has been broken should be used as soon as possible or within a few days.

Swallow the capsule or tablet whole and do not crush, chew, break, or open it.

Measure liquid medicine carefully. Use the dosing syringe provided, or use a medicine dose-measuring device (not a kitchen spoon).

Do not stop taking this medicine suddenly, even if you feel fine. Stopping suddenly may cause increased seizures. Follow your doctor's instructions about tapering your dose.

In case of emergency, wear or carry medical identification to let others know you have seizures.

This medicine can cause unusual results with certain medical tests. Tell any doctor who treats you that you are using gabapentin.

Store both the tablets and capsules at room temperature away from light and moisture.

Store the liquid medicine in the refrigerator. Do not freeze.

Dosing information

Usual Adult Dose for Epilepsy:

Initial dose: 300 mg orally on day one, 300 mg orally 2 times day on day two, then 300 mg orally 3 times a day on day three
Maintenance dose: 300 to 600 mg orally 3 times a day
Maximum dose: 3600 mg orally daily (in 3 divided doses)
-Maximum time between doses in the 3 times a day schedule should not exceed 12 hours

-The safety and effectiveness of gabapentin available under the trade name Gralise or Horizant in patients with epilepsy has not been studied.

Use: Adjunctive therapy in the treatment of partial onset seizures, with and without secondary generalization

Usual Adult Dose for Postherpetic Neuralgia:

-Initial dose: 300 mg orally on day one, 300 mg orally 2 times day on day two, then 300 mg orally 3 times a day on day three
-Titrate up as needed for pain relief
-Maximum dose: 1800 mg per day (600 mg orally 3 times a day)
Gabapentin available under the trade name Gralise:
-Maintenance dose: Gralise should be titrated to 1800 mg orally once daily with the evening meal.
-Recommended titration schedule:
Day 1: 300 mg orally with the evening meal
Day 2: 600 mg orally with the evening meal
Days 3 through 6: 900 mg orally with the evening meal
Days 7 through 10: 1200 mg orally with the evening meal
Days 11 through 14: 1500 mg orally with the evening meal
Day 15: 1800 mg orally with the evening meal
COMMENT:
-Gralise is not interchangeable with other gabapentin products because of differing pharmacokinetic profiles that affect the frequency of administration.

Gabapentin enacarbil extended release tablets are available under the trade name Horizant:
-The recommended dosage is 600 mg orally 2 times a day. Therapy should be initiated at a dose of 600 mg orally in the morning for 3 days of therapy, then increased to 600 mg 2 times a day (1200 mg/day) on day four.
COMMENT:
Gabapentin enacarbil extended release tablets available under the trade name Horizant and gabapentin are not interchangeable.

Use: Postherpetic neuralgia

Usual Adult Dose for Restless Legs Syndrome:

Gabapentin enacarbil available under the trade name Horizant:
600 mg orally once daily with food at about 5 PM

Use: For the treatment of moderate-to-severe primary Restless Legs Syndrome (RLS) in adults

Usual Pediatric Dose for Epilepsy:

Less than 3 years: Not recommended

Greater than or equal to 3 and less than 12 years:
Starting Dose: Ranges from 10 to 15 mg/kg/day in 3 divided doses
Effective Dose: Reached by upward titration over a period of approximately 3 days; the effective dose in patients 5 years of age and older is 25 to 35 mg/kg/day in divided doses (3 times a day). The effective dose in pediatric patients ages 3 and 4 years is 40 mg/kg/day and given in divided doses (3 times a day). Gabapentin may be administered as the oral solution, capsule, or tablet, or using combinations of these formulations. Dosages up to 50 mg/kg/day have been well tolerated in a long term clinical study. The maximum time interval between doses should not exceed 12 hours.

Greater than 12 years:
-Initial dose: 300 mg orally on day one, 300 mg orally 2 times a day on day two, then 300 mg orally 3 times a day on day three
-Maintenance dose: 900 to 1800 mg orally in 3 divided doses; the dose may be increased up to 1800 mg/day. Dosages up to 2400 mg/day have been well tolerated in long term clinical studies. Doses of 3600 mg/day have also been administered to a small number of patients for a relatively short duration, and have been well tolerated. The maximum time between doses in the three times a day schedule should not exceed 12 hours.

Use: Adjunctive therapy in the treatment of partial onset seizures, with and without secondary generalization in patients 3 years of age and older

What happens if I miss a dose?

Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time.

If you take Horizant: Skip the missed dose and use your next dose at the regular time. Do not use two doses of Horizant at one time.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What to avoid

Avoid driving or hazardous activity until you know how gabapentin will affect you. Your reactions could be impaired. Dizziness or drowsiness can cause falls, accidents, or severe injuries.

Avoid taking an antacid within 2 hours before you take gabapentin. Antacids can make it harder for your body to absorb gabapentin.

Avoid drinking alcohol while taking gabapentin.

Gabapentin side effects

Get emergency medical help if you have signs of an allergic reaction to gabapentin: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Seek medical treatment if you have a serious drug reaction that can affect many parts of your body. Symptoms may include: skin rash, fever, swollen glands, muscle aches, severe weakness, unusual bruising, upper stomach pain, or yellowing of your skin or eyes.

Report any new or worsening symptoms to your doctor, such as: mood or behavior changes, anxiety, panic attacks, trouble sleeping, or if you feel impulsive, irritable, agitated, hostile, aggressive, restless, hyperactive (mentally or physically), depressed, or have thoughts about suicide or hurting yourself.

Gabapentin may cause serious side effects. Call your doctor at once if you have:

• weak or shallow breathing;
• blue-colored skin, lips, fingers, and toes;
• confusion, extreme drowsiness or weakness;
• problems with balance or muscle movement;
• unusual or involuntary eye movements; or
• increased seizures.

Gabapentin can cause life-threatening breathing problems. A person caring for you should seek emergency medical attention if you have slow breathing with long pauses, blue colored lips, or if you are hard to wake up. Breathing problems may be more likely in older adults or in people with COPD.

Some side effects are more likely in children taking gabapentin. Contact your doctor if the child taking this medicine has any of the following side effects:

• changes in behavior;
• memory problems;
• trouble concentrating; or
• acting restless, hostile, or aggressive.

Common side effects of gabapentin may include:

• fever, chills, sore throat, body aches, unusual tiredness;
• jerky movements;
• headache;
• double vision;
• swelling of your legs and feet;
• tremors;
• trouble speaking;
• dizziness, drowsiness, tiredness;
• problems with balance or eye movements; or
• nausea, vomiting.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What other drugs will affect gabapentin?

Using gabapentin with other drugs that make you drowsy or slow your breathing can cause dangerous side effects or death. Ask your doctor before using opioid medication, a sleeping pill, cold or allergy medicine, a muscle relaxer, or medicine for anxiety or seizures.

other drugs may interact with gabapentin, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all your current medicines and any medicine you start or stop using.

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Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use gabapentin only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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