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Drug Profile

The information on this site is intended to supplement and enhance, not replace, the advice of a physician who is familiar with your medical history. Decisions about your health should always be made ONLY after detailed conversation with your doctor.

Limited Use [what does this mean?]
Generic drug name: gabapentin (NEURONTIN)
Brand name(s): GRALISE, NEURONTIN
GENERIC: available FAMILY: Drugs for Epilepsy
Find the drug label by searching at DailyMed.

Pregnancy and Breast-feeding Warnings [top]

Pregnancy Warning

Gabapentin caused fetal harm in animal studies, including delayed formation of the bones of the skull, back, arms, and legs and malformation of the kidney. Because of the potential for serious adverse effects to the fetus, this drug should not be used by pregnant women.

Breast-feeding Warning

Gabapentin is excreted in human milk. Because of the potential for serious adverse effects in nursing infants, you should not take this drug while nursing.

Safety Warnings For This Drug [top]

WARNING

  • Sudden death in patients with epilepsy
  • Severe, possibly life-threatening allergic (anaphylactic) reaction and angioedema that result in difficulty breathing; swelling of the lips, throat and tongue; and low blood pressure requiring emergency treatment
  • High eosinophil count (a type of white blood cell), associated with fever, rash and swelling of the lymph nodes, in addition to inflammation of the liver, kidneys, heart or muscles
  • Dizziness, drowsiness, somnolence, sedation and significant driving impairment
  • Lack of coordination, which can result in falls or injuries
  • Seizures that do not stop if the drug is discontinued abruptly
  • Neuropsychiatric adverse reactions — including emotional instability, hostility, aggression, impaired concentration, restlessness and hyperactivity — in children aged 12 and under

Facts About This Drug [top]

In 1993, the Food and Drug Administration (FDA) approved gabapentin (NEURONTIN) as an add-on treatment for focal (partial) seizures — a type of epilepsy that begins in one side of the brain — and subsequently approved the drug in 2002 to treat pain that occurs as a late complication of shingles (postherpetic neuralgia) in adults.[1] The agency later approved two different formulations of the drug: one (GRALISE) to treat shingles pain[2] and another (HORIZANT) to treat shingles pain and...

In 1993, the Food and Drug Administration (FDA) approved gabapentin (NEURONTIN) as an add-on treatment for focal (partial) seizures — a type of epilepsy that begins in one side of the brain — and subsequently approved the drug in 2002 to treat pain that occurs as a late complication of shingles (postherpetic neuralgia) in adults.[1] The agency later approved two different formulations of the drug: one (GRALISE) to treat shingles pain[2] and another (HORIZANT) to treat shingles pain and moderate-to-severe restless legs syndrome in adults[3].

Generic gabapentin and Neurontin should be used only for the treatment of partial seizures in combination with other antiepileptic drugs and for minimizing moderate-to-severe shingles pain. We recommend against using Gralise or Horizant for shingles pain because they are expensive and there are no studies that show them to be more effective than generic gabapentin. Do not use Gralise or Horizant for epilepsy, and do not use Gralise for restless legs syndrome. Finally, do not use any gabapentin formulation for off-label uses (uses not approved as safe and effective by the FDA).

Illegal promotion of unapproved uses

Gabapentin has been a top-selling drug for many years: It was the ninth-most commonly prescribed drug in the U.S. in 2016, totaling over 58 million prescriptions that year.[4]

However, most of gabapentin’s prescriptions are for off-label uses.[5] A study that used nationally representative data showed that gabapentin had, as of 2001, the highest proportion (83%) of off-label prescriptions of all outpatient prescription drugs.[6] Gabapentin’s off-label uses include treatment of anxiety, bipolar disorder, borderline personality disorder, drug and alcohol addiction, insomnia, migraine, neuropathic pain associated with diabetes, and vertigo.[5]

Pfizer, the company that acquired Warner-Lambert (the original maker of gabapentin) and its marketing division (Parke-Davis), agreed to pay a total of $755 million in 2004 and 2014 in criminal and civil settlements with the U.S. federal government for its long-standing illegal promotion of the drug for off-label uses.[7]

Furthermore, a 2013 study revealed that information included in publications of industry-sponsored trials supporting the off-label uses of gabapentin was frequently “different” from what was actually described in internal industry reports, suggesting that gabapentin’s maker deliberately manipulated the published literature to make the drug appear more effective than it actually is for its off-label uses.[8]

Limited Use: Epilepsy and shingles pain

Although the clinical trials supporting gabapentin’s initial approval showed that the drug is effective as an add-on treatment in people with drug-resistant partial epilepsy, these trials were of relatively short duration (lasting only three months) and did not provide any evidence regarding the long-term effectiveness of this drug.[9]

A clinical trial that directly compared gabapentin with other drugs used for the treatment of partial epilepsy such as lamotrigine (LAMICTAL) and carbamazepine (CARBATROL, EPITOL, EQUETRO, TEGRETOL, TERIL) showed that gabapentin had a higher rate of treatment failure and a lower rate of remission at one year than these other drugs, respectively, due to inadequate seizure control.[10] Importantly, gabapentin is ineffective for a type of seizures called absence seizures[11] and can worsen certain types of generalized seizures.[12]

Two small trials lasting between seven and eight weeks showed that gabapentin reduced, but did not eliminate, shingles pain: Subjects taking the drug had a mean pain score of around four (on a pain scale that ranged from 0 to 10) after treatment, compared with a not-much-higher pain score of nearly six before treatment.[1]

Despite its modest effectiveness, gabapentin has one advantage: It does not interact with other antiepileptic drugs. Gabapentin, however, is primarily eliminated by the kidneys, so adverse reactions to the drug may be more likely in patients with impaired kidney function.

Do Not Use: Restless legs syndrome

Gabapentin enacarbil extended release (HORIZANT) is approved to treat restless legs syndrome. However, high doses of this formulation are absorbed more efficiently by the intestine than high doses of other gabapentin formulations are, potentially resulting in greater, more serious adverse events.[13]

An FDA medical reviewer initially recommended against approving gabapentin enacarbil extended release because it causes pancreatic cancer in rats at doses relatively close to those used in humans, outweighing its potential benefit for restless legs syndrome.

Drug abuse potential

Historically, gabapentin was presumed to not have an abuse potential. However, there is growing evidence to the contrary. For example, a U.S. study showed an almost 3,000% increase in the recreational use of gabapentin from 2008 to 2014.[14]

Moreover, a 2016 systematic review estimated that misuse of gabapentin occurs in approximately 1% of the general population, between 40% and 65% of gabapentin users with prescriptions for the drug, and between 15% and 22% of opioid abusers.[4]

The Advisory Council on the Misuse of Drugs, an independent body of experts that advises the U.K. government, has highlighted concerns over the misuse of gabapentin in light of reports of abuse, dependence and involvement of gabapentin in opioid overdoses and opioid-related and other deaths.[15] The council asserts that gabapentin products present a risk of addiction and that the abuse potential of gabapentin is similar to that of tramadol (CONZIP, ULTRAM), a controlled substance in the U.K. and the U.S. Therefore, the council had recommended that gabapentin should be classified as a controlled substance.

In October 2017, the Medicines and Healthcare products Regulatory Agency, an agency in the U.K. similar to the FDA, issued a warning that gabapentin was associated with a risk of severe respiratory depression (decreased breathing), a dangerous adverse effect seen with opioid drugs.[16]

Suicide risk

Based on evidence from clinical trials, the FDA in 2008 required the makers of gabapentin, along with those of 10 other antiepileptic medications, to include a warning in their labeling and develop medication guides to inform patients of the risk of suicidal thoughts or actions associated with the drugs.[17]

In 2020, Lancet published results of a randomized clinical trial indicating that gabapentin was not effective for treating chronic pelvic pain in women.[18]

Regulatory actions:

In April 2019, the Medicines and Healthcare products Regulatory Agency (a regulatory agency in the U.K. similar to the FDA) announced that gabapentin would be classified as a controlled substance in the U.K.[19]

In September 2019, Health Canada (a regulatory agency in Canada similar to the FDA) issued an advisory that there is an increased risk of adverse effects, including opioid overdose, when gabapentin or pregabalin (LYRICA) is used together with opioid medications.[20]

In December 2019, the FDA issued an advisory that serious breathing problems can occur when gabapentin or pregabalin is used in the elderly and in patients who are at risk of breathing difficulties, including those taking opioids and other drugs that depress breathing through their effects on the central nervous system.[21] The product labeling for the drug was subsequently updated in April 2020 to include a warning about this risk.[22]

Before You Use This Drug [top]

Tell your doctor if you have or have had:

  • allergies to gabapentin or any ingredient in the formulation
  • kidney disease
  • pregnancy or are breast-feeding

Tell your doctor about any other drugs you take, including aspirin, herbs, vitamins, and other nonprescription products.

When You Use This Drug [top]

  • Do not drink alcohol or use other drugs that can cause drowsiness.
  • Until you know how you react to this drug, do not drive or perform other activities requiring alertness. Gabapentin can cause dizziness, blurred vision, drowsiness, and lack of muscle coordination.
  • Schedule regular visits with your doctor to check your progress, especially for the first few months you take gabapentin.
  • Do not stop taking this drug without consulting your doctor about gradually reducing the dosage.

How to Use This Drug [top]

  • Gabapentin should not be taken for at least two hours after any antacid is used.
  • Take with or without food.
  • If you miss a dose of gabapentin, take it as soon as possible. However, if it is less than two hours until your next dose, take the missed dose right away, and take the next dose one to two hours later. Then go back to your regular dosing schedule. Do not take double doses.
  • Do not exceed a 12-hour interval between any two doses while on a three-times-a-day dosing schedule.
  • Do not share your medication with others.
  • Take the drug at the same time(s) each day.
  • Store capsules and tablets at room temperature with lid on tightly. Do not store in the bathroom. Do not expose to heat, moisture, or strong light. Keep out of reach of children.
  • Immediately before use: Tablets or capsules may be mixed in with food or drink. Capsules may be opened and the contents mixed with applesauce, jelly, or ketchup, then swallowed without chewing.
  • Store the liquid form of the drug in the refrigerator, but keep it from freezing. Also dissolve each dose as needed; do not dissolve ahead of time.

Interactions with Other Drugs [top]

Evaluations of Drug Interactions 2003 lists no drugs, biologics (e.g., vaccines, therapeutic antibodies), or foods as causing “highly clinically significant” or “clinically significant” interactions when used together with the drugs in this section. We also found no interactions in the drugs’ FDA-approved professional package inserts. However, as the number of new drugs approved for marketing increases and as more experience is gained with these drugs over time, new interactions may be discovered.

Adverse Effects [top]

Call your doctor immediately if you experience:

  • clumsiness or unsteadiness
  • continuous, uncontrolled, back-and-forth, and/or rolling eye movements
  • memory loss
  • depression, irritability, or other mood or mental changes
  • fever
  • chills
  • cough or hoarseness
  • lower back or side pain
  • painful or difficult urination

Call your doctor if these symptoms continue:

  • weakness or loss of strength
  • dizziness
  • fatigue
  • muscle ache or pain
  • swelling of hands, feet, or lower legs
  • drowsiness
  • trembling or shaking
  • blurred or double vision
  • dry mouth or throat
  • slurred speech
  • frequent urination
  • constipation
  • diarrhea
  • nausea or vomiting
  • indigestion
  • headache
  • low blood pressure
  • decreased sexual desire or ability
  • trouble sleeping
  • runny nose
  • noise in ears
  • twitching
  • weight gain

Signs of overdose:

  • diarrhea
  • double vision
  • slurred speech
  • sluggishness
  • drowsiness

If you suspect an overdose, call this number to contact your poison control center: (800) 222-1222.

last reviewed June 30, 2021