OverviewDosageSide EffectsInteractionsHalf-Life

The following information comes from DailyMed, the official FDA label information provider for drugs.

The following serious adverse reactions of gabapentin are discussed in greater detail in other sections:

  • Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS)/Multiorgan Hypersensitivity
  • Anaphylaxis and Angioedema
  • Somnolence/Sedation and Dizziness
  • Withdrawal Precipitated Seizure, Status Epilepticus
  • Suicidal Behavior and Ideation
  • Neuropsychiatric Adverse Reactions (most commonly in pediatric patients)
  • Sudden and Unexplained Death in Patients with Epilepsy
  • Respiratory depression

Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

Postherpetic Neuralgia

The most common adverse reactions associated with the use of gabapentin in adults, not seen at an equivalent frequency among placebo-treated patients, were dizziness, somnolence, and peripheral edema (swelling of extremities but not limited to extremities).

In the 2 controlled trials in postherpetic neuralgia, 16% of the 336 patients who received gabapentin and 9% of the 227 patients who received placebo discontinued treatment because of an adverse reaction. The adverse reactions that most frequently led to withdrawal in gabapentin-treated patients were dizziness, somnolence, and nausea.

Table 3 lists adverse reactions that occurred in at least 1% of gabapentin-treated patients with postherpetic neuralgia participating in placebo-controlled trials and that were numerically more frequent in the gabapentin group than in the placebo group.

TABLE 3.  Adverse Reactions in Pooled Placebo-Controlled Trials in Postherpetic Neuralgia

GabapentinN=336%PlaceboN=227%
Body as a Whole
Asthenia65
Infection54
Accidental injury31
Digestive System
Diarrhea63
Dry mouth51
Constipation42
Nausea43
Vomiting32
Metabolic and Nutritional Disorders
Peripheral edema82
Weight gain20
Hyperglycemia10
Nervous System
Dizziness288
Somnolence215
Ataxia30
Abnormal thinking30
Abnormal gait20
Incoordination20
Respiratory System
Pharyngitis10
Special Senses
Amblyopia31
Conjunctivitis10
Diplopia10
Otitis media10
a Reported as blurred vision

Other reactions in more than 1% of patients but equally or more frequent in the placebo group included pain, tremor, neuralgia, back pain, dyspepsia, dyspnea, and flu syndrome.

There were no clinically important differences between men and women in the types and incidence of adverse reactions. Because there were few patients whose race was reported as other than white, there is insufficient data to support a statement regarding the distribution of adverse reactions by race.

Epilepsy with Partial Onset Seizures (Adjunctive Therapy) 

The most common adverse reactions with gabapentin in combination with other antiepileptic drugs in patients >12 years of age, not seen at an equivalent frequency among placebo-treated patients, were somnolence, dizziness, ataxia, fatigue, and nystagmus.

The most common adverse reactions with gabapentin in combination with other antiepileptic drugs in pediatric patients 3 to 12 years of age, not seen at an equal frequency among placebo-treated patients, were viral infection, fever, nausea and/or vomiting, somnolence, and hostility [see Warnings and Precautions (5.7)].

Approximately 7% of the 2,074 patients > 12 years of age and approximately 7% of the 449 pediatric patients 3 to 12 years of age who received gabapentin in premarketing clinical trials discontinued treatment because of an adverse reaction. The adverse reactions most commonly associated with withdrawal in patients > 12 years of age were somnolence (1.2%), ataxia (0.8%), fatigue (0.6%), nausea and/or vomiting (0.6%), and dizziness (0.6%). The adverse reactions most commonly associated with withdrawal in pediatric patients were emotional lability (1.6%), hostility (1.3%), and hyperkinesia (1.1%).

Table 4 lists adverse reactions that occurred in at least 1% of gabapentin-treated patients > 12 years of age with epilepsy participating in placebo-controlled trials and were numerically more common in the gabapentin group. In these studies, either gabapentin or placebo was added to the patient’s current antiepileptic drug therapy.

TABLE 4. Adverse Reactions in Pooled Placebo-Controlled Add-On Trials In Epilepsy Patients > 12 years of age

GabapentinaN=543%PlaceboaN=378%
Body As A Whole
Fatigue115
Increased Weight32
Back Pain21
Peripheral Edema21
Cardiovascular
Vasodilatation10
Digestive System
Dyspepsia21
Dry Mouth or Throat21
Constipation21
Dental Abnormalities20
Nervous System
Somnolence199
Dizziness177
Ataxia136
Nystagmus84
Tremor73
Dysarthria21
Amnesia20
Depression21
Abnormal thinking21
Abnormal coordination10
Respiratory System
Pharyngitis32
Coughing21
Skin and Appendages
Abrasion10
Urogenital System
Impotence21
Special Senses
Diplopia62
Amblyopia41
a Plus background antiepileptic drug therapyb Amblyopia was often described as blurred vision.

Among the adverse reactions occurring at an incidence of at least 10% in gabapentin-treated patients, somnolence and ataxia appeared to exhibit a positive dose-response relationship.

The overall incidence of adverse reactions and the types of adverse reactions seen were similar among men and women treated with gabapentin. The incidence of adverse reactions increased slightly with increasing age in patients treated with either gabapentin or placebo. Because only 3% of patients (28/921) in placebo-controlled studies were identified as nonwhite (black or other), there are insufficient data to support a statement regarding the distribution of adverse reactions by race.

Table 5 lists adverse reactions that occurred in at least 2% of gabapentin-treated patients, age 3 to 12 years of age with epilepsy participating in placebo-controlled trials, and which were numerically more common in the gabapentin group.

TABLE 5.  Adverse Reactions in a Placebo-Controlled Add-On Trial in Pediatric Epilepsy Patients Age 3 to 12 Years

GabapentinaN=119%PlaceboaN=128%
Body As A Whole
Viral Infection113
Fever103
Increased Weight31
Fatigue32
Digestive System
Nausea and/or Vomiting87
Nervous System
Somnolence85
Hostility82
Emotional Lability42
Dizziness32
Hyperkinesia31
Respiratory System
Bronchitis31
Respiratory Infection31
a Plus background antiepileptic drug therapy

Other reactions in more than 2% of pediatric patients 3 to 12 years of age but equally or more frequent in the placebo group included: pharyngitis, upper respiratory infection, headache, rhinitis, convulsions, diarrhea, anorexia, coughing, and otitis media.

Postmarketing Experience

The following adverse reactions have been identified during post marketing use of gabapentin. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

Hepatobiliary disorders: jaundice

Investigations: elevated creatine phosphokinase, elevated liver enzymes

Metabolism and nutrition disorders: hyponatremia, changes in serum glucose

Musculoskeletal and connective tissue disorder: rhabdomyolysis

Nervous system disorders: movement disorder

Psychiatric disorders: agitation

Reproductive system and breast disorders: breast hypertrophy, changes in libido, ejaculation disorders and anorgasmia

Skin and subcutaneous tissue disorders: angioedema, erythema multiforme, Stevens-Johnson syndrome.

Adverse reactions following the abrupt discontinuation of gabapentin have also been reported. The most frequently reported reactions were anxiety, insomnia, nausea, pain, and sweating.

*Abrupt discontinuation is not recommended without provider approval, as serious side effects such as seizures can occur. Consult your medical provider before discontinuation.

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