Reviewed on 8/5/2021

What Is Gabapentin and How Does It Work?

Gabapentin is a prescription drug most commonly prescribed to relieve nerve pain following shingles in adults, treating the pain of post herpetic neuralgia. Gabapentin belongs to a class of drugs known as anti-seizure drugs.

  • Take gabapentin by mouth as directed by your doctor, usually once a day with the evening meal. The dosage is based on your medical condition and response to treatment.
  • Swallow gabapentin whole. Do not crush or chew sustained-release tablets. Doing so can release all of the drug at once, increasing the risk of side effects. Also, do not split sustained-release tablets unless they have a score line and your doctor or pharmacist tells you to do so. Swallow the whole or split tablet without crushing or chewing.
  • During the first 2 weeks of treatment, your doctor may gradually increase your dose so your body can adjust to the medication.
  • Gabapentin is available under the following different brand names: Neurontin and Gralise.

What Are the Dosages of Gabapentin?

Dosages of Gabapentin

Adult and pediatric dosages:


  • 100 mg
  • 300 mg
  • 400 mg


  • 300 mg (Gralise)
  • 600 mg (Gralise, Neurontin)
  • 800 mg (Neurontin)
Dosage Considerations – Should be Given as Follows:
  • Reducing the dose, discontinuing the drug, or substituting an alternative medication should be done gradually over a minimum of 1 week or longer.
Geritric dosing considerations:
  • Renal impairment is present, gabapentin dose reduction may be required, depending on renal function.
Partial Seizures
  • Neurontin
  • Adjunctive therapy for partial seizures with or without secondary generalization.
  • Initial: 300 mg orally every 8 hours.
  • May increase up to 600 mg orally every 8 hours; up to 2400 mg/day administered and tolerated in clinical studies; up to 3600 mg administered for short duration and tolerated
Post herpetic Neuralgia
  • Neurontin
  • Day 1: 300 mg orally once per day.
  • Day 2: 300 mg orally every 12 hours.
  • Day 3: 300 mg orally every 8 hours.

Maintenance: Subsequently titrate as needed up to 600 mg orally every 8 hours; doses greater than 1800 mg/day have demonstrated no additional benefit.


  • Dose gradually to 1800 mg/day orally; take once a day with evening meal.
  • Day 1: 300 mg orally once a day.
  • Day 2: 600 mg orally once a day.
  • Days 3-6: 900 mg orally once a day.
  • Days 7-10: 1200 mg orally once a day.
  • Days 11-14: 1500 mg orally once a day.
  • Day 15 and after (maintenance): 1800 mg orally once a day.

Dosing considerations:

  • Gralise tablets swell in gastric fluid and gradually release gabapentin. Swallow Gralise tablets whole; do not cut, crush, or chew them.

Dosing Modifications:

Renal impairment (Neurontin)

  • Creatinine clearance greater than 60 mL/min: 300-1200 mg orally twice daily
  • Creatinine clearance 30-60 mL/min: 200-700 mg every 12 hours
  • Creatinine clearance 15-29 mL/min: 200-700 mg once per day
  • Creatinine clearance less than 15 mL/min: 100-300 mg once per day
Hemodialysis (Creatinine clearance less than 15 mL/min):
  • Administer supplemental dose (range 125-350 mg) post hemodialysis, after each 4 hour dialysis interval; further dose reduction should be in proportion to Creatinine clearance (a Creatinine clearance of 7.5 mL/min should receive one-half daily post hemodialysis dose)
Renal impairment (Gralise):
  • Creatinine clearance is greater than or equal to 60 mL/min: 1800 mg daily with evening meal
  • Creatinine clearance 30-59 mL/min: 600-1800 mg daily with evening meal
  • Creatinine clearance greater than 30 mL/min or hemodialysis: Do not administer


What Is Epilepsy? Symptoms, Causes, and Treatments See Slideshow

What Are Side Effects Associated with Using Gabapentin?

Side effects of gabapentin include:

  • lack of muscle coordination
  • dizziness
  • drowsiness
  • fatigue
  • sleep for unusually long periods
  • double vision
  • repetitive eye movement
  • tremor
  • reduced vision
  • back pain
  • constipation
  • depression
  • dry mouth
  • slurring of speech
  • hostility
  • muscle spasm
  • increased appetite
  • reduction of white blood cells
  • muscle pain
  • nervousness
  • swelling caused by fluid
  • hoarseness
  • severe itching
  • runny nose
  • decreased blood pressure
  • weight gain
  • abnormal vision
  • loss of appetite
  • joint pain
  • physical weakness or lack of energy
  • high blood pressure
  • generalized discomfort
  • burning or prickling sensation in hands or feet
  • skin discoloration
  • spinning sensation (vertigo)
  • swelling
  • blood sugar (glucose) fluctuation
  • breast enlargement
  • skin reaction caused by acute hypersensitivity
  • elevated liver function tests
  • fever
  • low sodium level
  • yellow skin or eyes (jaundice)
  • Steven-Johnson syndrome
  • changes in libido
  • ejaculation disorders
  • sexual dysfunction

Side effects associated with abrupt discontinuation:

  • anxiety
  • insomnia
  • nausea
  • pain
  • sweating

Post marketing side effects of Gabapentin reported include:

  • swelling
  • blood glucose fluctuation
  • breast enlargement
  • skin reaction caused by acute hypersensitivity
  • elevated liver function tests
  • fever
  • low sodium level
  • yellow skin or eyes (jaundice)
  • Steven-Johnson syndrome
  • changes in libido
  • ejaculation disorders
  • sexual dysfunction

This document does not contain all possible side effects and others may occur. Check with your physician for additional information about side effects.

What Other Drugs Interact with Gabapentin?

If your doctor has directed you to use this medication for diabetes, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider or pharmacist first.

Gabapentin has no known severe interactions with any drugs.

Serious Interactions of Gabapentin include:

  • hydrocodone
  • valerian
  • Moderate Interactions of Gabapentin include:

  • aluminum hydroxide
  • calcium carbonate
  • clobazam
  • lurasidone
  • morphine
  • orlistat
  • sevelamer
  • sodium bicarbonate
  • sodium citrate/citric acid
  • Gabapentin has mild interactions with at least 21 different drugs.

    This document does not contain all possible interactions. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your medications with you, and share the list with your doctor and pharmacist. Check with your physician if you have health questions or concerns.

    What Are Warnings and Precautions for Gabapentin?


    Do not discontinue abruptly as it may increase seizure frequency; gradually taper over a minimum of 1 week.

    This medication contains gabapentin. Do not take Neurontin or Gralise if you are allergic to gabapentin or any ingredients contained in this drug.

    Keep out of reach of children. In case of overdose, get medical help or contact a Poison Control Center immediately.


    Do not use if you are hypersensitive.

    Administration of live or attenuated live vaccine (Advisory Committee on Immunization Practices (ACIP) and American Academy of Family Physicians (AAFP) state that administration of live virus vaccines usually is not contraindicated in patients receiving corticosteroid therapy as short-term (less than 2 weeks) treatment, in low-to-moderate dosages, as long-term alternate-day treatment with short-acting preparations, or in maintenance of physiologic dosages, such as, replacement therapy.

    Effects of Drug Abuse

    No information provided.

    Short-Term Effects

    See "What Are Side Effects Associated with Using Gabapentin?"

    Long-Term Effects

    See also "What Are Side Effects Associated with Using Gabapentin?"


    Reported increased blood creatinine phosphokinase levels and muscle damage caused by inflammation.

    Antiepileptic drugs increase risk of suicidal thoughts or behavior in patients taking these drugs for any indication; monitor for emergence or worsening depression, suicidal thoughts or behavior, and/or any unusual changes in mood or behavior.

    Anaphylaxis and angioedema reported after first dose or at any time during treatment; instruct patients to discontinue therapy and seek medical care should they experience signs or symptoms of anaphylaxis or angioedema.

    May cause central nervous system depression, which may impair ability to operate heavy machinery; advise patients not to drive until they have gained enough experience to assess whether therapy will impair ability to drive.

    Extended release formulation (Gralise) not studied in the treatment of seizures.

    Extended release formulation (Gralise) not interchangeable with immediate release.

    May potentiate effects of other sedatives or ethanol when administered concomitantly.

    Do not discontinue abruptly as it may increase seizure frequency; gradually taper over a minimum of 1 week.

    Ages 3-12 years: Risk of neuropsychiatric adverse events, including emotional lability, hostility, thought disorders, and hyperkinesia.

    Drug reaction with eosinophilia and systemic symptoms, also known as multi-organ hypersensitivity, reported; some of these events have been fatal or life-threatening; typically presents with fever, rash, and/or lymphadenopathy in association with other organ system involvement (hepatitis, nephritis, hematologic abnormalities, myocarditis, and myositis) and may resemble an acute viral infection.

    Pregnancy and Lactation

    Use gabapentin with caution if benefits outweigh risks in pregnancy. Animal studies show risk and human studies are not yet available or neither animal nor human studies have been done.

    Gabapentin transfers into breast milk, consult with your physician.


    If you have had a seizure, it means you have epilepsy. See Answer
    Medscape. Gabapentin.

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