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Gabapentin Side Effects

Brand Names: Neurontin

Please note - some side effects for Gabapentin may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA at http://www.fda.gov/medwatch/ or 1-800-FDA-1088 (1-800-332-1088).


Side Effects of Gabapentin - for the Consumer

Gabapentin

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Gabapentin:

Back pain; changes in vision (double or blurred vision); clumsiness; constipation; diarrhea; dizziness; drowsiness; dry mouth; nausea; stomach upset; tiredness; vomiting; weight gain.

Seek medical attention right away if any of these SEVERE side effects occur when using Gabapentin:

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); abnormal thoughts; aggressive behavior; back and forth eye movements; behavioral problems; change in school performance; chest pain; confusion; fainting; fast, slow, or irregular heartbeat; fever, chills, or sore throat; hyperactivity; loss of coordination; memory loss; mental or mood changes (eg, hostility, mood swings); numbness of an arm or leg; one-sided weakness; restlessness; seizures; severe headache or dizziness; shortness of breath; speech changes; suicidal thoughts or actions; swelling of the hands, legs, or feet; tremor; trouble concentrating; twitching.

Gabapentin Capsules

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Gabapentin Capsules:

Back pain; changes in vision (double or blurred vision); clumsiness; constipation; diarrhea; dizziness; drowsiness; dry mouth; nausea; stomach upset; tiredness; vomiting; weight gain.

Seek medical attention right away if any of these SEVERE side effects occur when using Gabapentin Capsules:

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); abnormal thoughts; aggressive behavior; back and forth eye movements; behavioral problems; change in school performance; chest pain; confusion; fainting; fast, slow, or irregular heartbeat; fever, chills, or sore throat; hyperactivity; loss of coordination; memory loss; mental or mood changes (eg, hostility, mood swings); numbness of an arm or leg; one-sided weakness; restlessness; seizures; severe headache or dizziness; shortness of breath; speech changes; suicidal thoughts or actions; swelling of the hands, legs, or feet; tremor; trouble concentrating; twitching.

Gabapentin Solution

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Gabapentin Solution:

Back pain; changes in vision (double or blurred vision); clumsiness; constipation; diarrhea; dizziness; drowsiness; dry mouth; nausea; stomach upset; tiredness; vomiting; weight gain.

Seek medical attention right away if any of these SEVERE side effects occur when using Gabapentin Solution:

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); abnormal thoughts; aggressive behavior; back and forth eye movements; behavioral problems; change in school performance; chest pain; confusion; fainting; fast, slow, or irregular heartbeat; fever, chills, or sore throat; hyperactivity; loss of coordination; memory loss; mental or mood changes (eg, hostility, mood swings); numbness of an arm or leg; one-sided weakness; restlessness; seizures; severe headache or dizziness; shortness of breath; speech changes; suicidal thoughts or actions; swelling of the hands, legs, or feet; tremor; trouble concentrating; twitching.

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Gabapentin Side Effects - for the Professional

Gabapentin

Postherpetic Neuralgia

The most commonly observed adverse events associated with the use of Gabapentin Capsules in adults, not seen at an equivalent frequency among placebo-treated patients, were dizziness, somnolence, and peripheral edema.

In the 2 controlled studies in postherpetic neuralgia, 16% of the 336 patients who received Gabapentin Capsules and 9% of the 227 patients who received placebo discontinued treatment because of an adverse event. The adverse events that most frequently led to withdrawal in Gabapentin Capsule-treated patients were dizziness, somnolence, and nausea.

Incidence in Controlled Clinical Trials

TABLE 3 lists treatment-emergent signs and symptoms that occurred in at least 1% of Gabapentin Capsules-treated patients with postherpetic neuralgia participating in placebo-controlled trials and that were numerically more frequent in the Gabapentin Capsules group than in the placebo group. Adverse events were usually mild to moderate in intensity.

TABLE 3. Treatment-Emergent Adverse Event Incidence in Controlled Trials in Postherpetic Neuralgia (Events in at least 1% of Gabapentin Capsules-Treated Patients and Numerically More Frequent Than in the Placebo Group)
 a Reported as blurred vision
 Body System/ Preferred Term  Gabapentin Capsules  Placebo
   N = 336  N = 227
   %  %
 Body as a Whole    
 Asthenia  5.7  4.8
 Infection  5.1  3.5
 Headache  3.3  4.1
 Accidental injury  3.3  1.3
 Abdominal pain  2.7  2.6
 Digestive System    
 Diarrhea  5.7  3.1
 Dry Mouth  4.8  1.3
 Constipation  3.9  1.8
 Nausea  3.9  3.1
 Vomiting  3.3  1.8
 Flatulence  2.1  1.8
 Metabolic and Nutritional Disorders    
 Peripheral edema  8.3  2.2
 Weight gain  1.8  0.0
 Hyperglycemia  1.2  0.4
 Nervous System    
 Dizziness  28.0  7.5
 Somnolence  21.4  5.3
 Ataxia  3.3  0.0
 Thinking abnormal  2.7  0.0
 Abnormal gait  1.5  0.0
 Incoordination  1.5  0.0
 Amnesia  1.2  0.9
 Hypesthesia  1.2  0.9
 Respiratory System    
 Pharyngitis  1.2  0.4
 Skin and Appendages    
 Rash  1.2  0.9
 Special Senses    
 Amblyopiaa  2.7  0.9
 Conjunctivitis  1.2  0.0
 Diplopia  1.2  0.0
 Otitis media  1.2  0.0

Other events 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 events. Because there were few patients whose race was reported as other than white, there are insufficient data to support a statement regarding the distribution of adverse events by race.

Epilepsy

The most commonly observed adverse events associated with the use of 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 commonly observed adverse events reported with the use of 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.

Approximately 7% of the 2074 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 event. The adverse events 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 events most commonly associated with withdrawal in pediatric patients were emotional lability (1.6%), hostility (1.3%), and hyperkinesia (1.1%).

Incidence in Controlled Clinical Trials

TABLE 4 lists treatment-emergent signs and symptoms that occurred in at least 1% of Gabapentin Capsules-treated patients > 12 years of age with epilepsy participating in placebo-controlled trials and were numerically more common in the Gabapentin Capsules group. In these studies, either Gabapentin Capsules or placebo was added to the patient’s current antiepileptic drug therapy. Adverse events were usually mild to moderate in intensity.

The prescriber should be aware that these figures, obtained when Gabapentin Capsules were added to concurrent antiepileptic drug therapy, cannot be used to predict the frequency of adverse events in the course of usual medical practice where patient characteristics and other factors may differ from those prevailing during clinical studies. Similarly, the cited frequencies cannot be directly compared with figures obtained from other clinical investigations involving different treatments, uses, or investigators. An inspection of these frequencies, however, does provide the prescribing physician with one basis to estimate the relative contribution of drug and nondrug factors to the adverse event incidences in the population studied.

TABLE 4. Treatment-Emergent Adverse Event Incidence in Controlled Add-On Trials in Patients > 12 Years of Age (Events in at Least 1% of Gabapentin Capsules patients and numerically more frequent than in the placebo group)
 a Plus background antiepileptic drug therapy

b Amblyopia was often described as blurred vision

 Body System/ Adverse Event  Gabapentin Capsulesa  Placeboa
   N = 543  N = 378
   %  %
 Body As A Whole    
 Fatigue  11.0  5.0
 Weight Increase  2.9  1.6
 Back Pain  1.8  0.5
 Peripheral Edema  1.7  0.5
 Cardiovascular    
 Vasodilatation  1.1  0.3
 Digestive System    
 Dyspepsia  2.2  0.5
 Mouth or Throat Dry  1.7  0.5
 Constipation  1.5  0.8
 Dental Abnormalities  1.5  0.3
 Increased Appetite  1.1  0.8
 Hematologic and Lymphatic Systems    
 Leukopenia  1.1  0.8
 Musculoskeletal System    
 Myalgia  2.0  1.9
 Fracture  1.1  0.8
 Nervous System    
 Somnolence  19.3  8.7
 Dizziness  17.1  6.9
 Ataxia  12.5  5.6
 Nystagmus  8.3  4.0
 Tremor  6.8  3.2
 Nervousness  2.4  1.9
 Dysarthria  2.4  0.5
 Amnesia  2.2  0.0
 Depression  1.8  1.1
 Thinking Abnormal  1.7  1.3
 Twitching  1.3  0.5
 Coordination Abnormal  1.1  0.3
 Respiratory System    
 Rhinitis  4.1  3.7
 Pharyngitis  2.8  1.6
 Coughing  1.8  1.3
 Skin and Appendages    
 Abrasion  1.3  0.0
 Pruritus  1.3  0.5
 Urogenital System    
 Impotence  1.5  1.1
 Special Senses    
 Diplopia  5.9  1.9
 Amblyopiab  4.2  1.1
 Laboratory Deviations    
 WBC Decreased  1.1  0.5

Other events in more than 1% of patients > 12 years of age but equally or more frequent in the placebo group included: headache, viral infection, fever, nausea and/or vomiting, abdominal pain, diarrhea, convulsions, confusion, insomnia, emotional lability, rash, acne.

Among the treatment-emergent adverse events occurring at an incidence of at least 10% of Gabapentin Capsules-treated patients, somnolence and ataxia appeared to exhibit a positive dose-response relationship.

The overall incidence of adverse events and the types of adverse events seen were similar among men and women treated with Gabapentin Capsules. The incidence of adverse events increased slightly with increasing age in patients treated with either Gabapentin Capsules 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 events by race.

TABLE 5lists treatment-emergent signs and symptoms that occurred in at least 2% of Gabapentin Capsules-treated patients age 3 to 12 years of age with epilepsy participating in placebo-controlled trials and were numerically more common in the Gabapentin Capsules group. Adverse events were usually mild to moderate in intensity.

TABLE 5. Treatment-Emergent Adverse Event Incidence in Pediatric Patients Age 3 to 12 Years in a Controlled Add-On Trial (Events in at least 2% of Gabapentin Capsules patients and numerically more frequent than in the placebo group)
 a Plus background antiepileptic drug therapy
 Body System/ Adverse Event  Gabapentin Capsulesa  Placeboa
   N = 119  N = 128
   %  %
 Body As A Whole    
 Viral Infection  10.9  3.1
 Fever  10.1  3.1
 Weight Increase  3.4  0.8
 Fatigue  3.4  1.6
 Digestive System    
 Nausea and/or Vomiting  8.4  7.0
 Nervous System    
 Somnolence  8.4  4.7
 Hostility  7.6  2.3
 Emotional Lability  4.2  1.6
 Dizziness  2.5  1.6
 Hyperkinesia  2.5  0.8
 Respiratory System    
 Bronchitis  3.4  0.8
 Respiratory Infection  2.5  0.8

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

Other Adverse Events Observed During All Clinical Trials

Clinical Trials in Adults and Adolescents (Except Clinical Trials in Neuropathic Pain)

Gabapentin Capsules have been administered to 4717 patients > 12 years of age during all adjunctive therapy clinical trials (except clinical trials in patients with neuropathic pain), only some of which were placebo-controlled. During these trials, all adverse events were recorded by the clinical investigators using terminology of their own choosing. To provide a meaningful estimate of the proportion of individuals having adverse events, similar types of events were grouped into a smaller number of standardized categories using modified COSTART dictionary terminology. These categories are used in the listing below. The frequencies presented represent the proportion of the 4717 patients > 12 years of age exposed to Gabapentin Capsules who experienced an event of the type cited on at least one occasion while receiving Gabapentin Capsules. All reported events are included except those already listed in Table 4, those too general to be informative, and those not reasonably associated with the use of the drug.

Events are further classified within body system categories and enumerated in order of decreasing frequency using the following definitions: frequent adverse events are defined as those occurring in at least 1/100 patients; infrequent adverse events are those occurring in 1/100 to 1/1000 patients; rare events are those occurring in fewer than 1/1000 patients.

Body As A Whole: Frequent: asthenia, malaise, face edema; Infrequent: allergy, generalized edema, weight decrease, chill; Rare: strange feelings, lassitude, alcohol intolerance, hangover effect.

Cardiovascular System: Frequent: hypertension; Infrequent: hypotension, angina pectoris, peripheral vascular disorder, palpitation, tachycardia, migraine, murmur; Rare: atrial fibrillation, heart failure, thrombophlebitis, deep thrombophlebitis, myocardial infarction, cerebrovascular accident, pulmonary thrombosis, ventricular extrasystoles, bradycardia, premature atrial contraction, pericardial rub, heart block, pulmonary embolus, hyperlipidemia, hypercholesterolemia, pericardial effusion, pericarditis.

Digestive System: Frequent: anorexia, flatulence, gingivitis; Infrequent: glossitis, gum hemorrhage, thirst, stomatitis, increased salivation, gastroenteritis, hemorrhoids, bloody stools, fecal incontinence, hepatomegaly; Rare: dysphagia, eructation, pancreatitis, peptic ulcer, colitis, blisters in mouth, tooth discolor, perlèche, salivary gland enlarged, lip hemorrhage, esophagitis, hiatal hernia, hematemesis, proctitis, irritable bowel syndrome, rectal hemorrhage, esophageal spasm.

Endocrine System: Rare: hyperthyroid, hypothyroid, goiter, hypoestrogen, ovarian failure, epididymitis, swollen testicle, cushingoid appearance.

Hematologic and Lymphatic System: Frequent: purpura most often described as bruises resulting from physical trauma; Infrequent: anemia, thrombocytopenia, lymphadenopathy; Rare: WBC count increased, lymphocytosis, non-Hodgkin’s lymphoma, bleeding time increased.

Musculoskeletal System: Frequent: arthralgia; Infrequent: tendinitis, arthritis, joint stiffness, joint swelling, positive Romberg test; Rare: costochondritis, osteoporosis, bursitis, contracture.

Nervous System: Frequent: vertigo, hyperkinesia, paresthesia, decreased or absent reflexes, increased reflexes, anxiety, hostility; Infrequent: CNS tumors, syncope, dreaming abnormal, aphasia, hypesthesia, intracranial hemorrhage, hypotonia, dysesthesia, paresis, dystonia, hemiplegia, facial paralysis, stupor, cerebellar dysfunction, positive Babinski sign, decreased position sense, subdural hematoma, apathy, hallucination, decrease or loss of libido, agitation, paranoia, depersonalization, euphoria, feeling high, doped-up sensation, psychosis; Rare: choreoathetosis, orofacial dyskinesia, encephalopathy, nerve palsy, personality disorder, increased libido, subdued temperament, apraxia, fine motor control disorder, meningismus, local myoclonus, hyperesthesia, hypokinesia, mania, neurosis, hysteria, antisocial reaction.

Respiratory System: Frequent: pneumonia; Infrequent: epistaxis, dyspnea, apnea; Rare: mucositis, aspiration pneumonia, hyperventilation, hiccup, laryngitis, nasal obstruction, snoring, bronchospasm, hypoventilation, lung edema.

Dermatological: Infrequent: alopecia, eczema, dry skin, increased sweating, urticaria, hirsutism, seborrhea, cyst, herpes simplex; Rare: herpes zoster, skin discolor, skin papules, photosensitive reaction, leg ulcer, scalp seborrhea, psoriasis, desquamation, maceration, skin nodules, subcutaneous nodule, melanosis, skin necrosis, local swelling.

Urogenital System: Infrequent: hematuria, dysuria, urination frequency, cystitis, urinary retention, urinary incontinence, vaginal hemorrhage, amenorrhea, dysmenorrhea, menorrhagia, breast cancer, unable to climax, ejaculation abnormal; Rare: kidney pain, leukorrhea, pruritus genital, renal stone, acute renal failure, anuria, glycosuria, nephrosis, nocturia, pyuria, urination urgency, vaginal pain, breast pain, testicle pain.

Special Senses: Frequent: abnormal vision; Infrequent: cataract, conjunctivitis, eyes dry, eye pain, visual field defect, photophobia, bilateral or unilateral ptosis, eye hemorrhage, hordeolum, hearing loss, earache, tinnitus, inner ear infection, otitis, taste loss, unusual taste, eye twitching, ear fullness; Rare: eye itching, abnormal accommodation, perforated ear drum, sensitivity to noise, eye focusing problem, watery eyes, retinopathy, glaucoma, iritis, corneal disorders, lacrimal dysfunction, degenerative eye changes, blindness, retinal degeneration, miosis, chorioretinitis, strabismus, eustachian tube dysfunction, labyrinthitis, otitis externa, odd smell.

Clinical Trials in Pediatric Patients With Epilepsy

Adverse events occurring during epilepsy clinical trials in 449 pediatric patients 3 to 12 years of age treated with Gabapentin that were not reported in adjunctive trials in adults are:

Body as a Whole: dehydration, infectious mononucleosis

Digestive System: hepatitis

Hemic and Lymphatic System: coagulation defect

Nervous System: aura disappeared, occipital neuralgia

Psychobiologic Function: sleepwalking

Respiratory System: pseudocroup, hoarseness

Clinical Trials in Adults With Neuropathic Pain of Various Etiologies

Safety information was obtained in 1173 patients during double-blind and open-label clinical trials including neuropathic pain conditions for which efficacy has not been demonstrated. Adverse events reported by investigators were grouped into standardized categories using modified COSTART IV terminology. Listed below are all reported events except those already listed in Table 3 and those not reasonably associated with the use of the drug.

Events are further classified within body system categories and enumerated in order of decreasing frequency using the following definitions: frequent adverse events are defined as those occurring in at least 1/100 patients; infrequent adverse events are those occurring in 1/100 to 1/1000 patients; rare events are those occurring in fewer than 1/1000 patients.

Body as a Whole: Infrequent: chest pain, cellulitis, malaise, neck pain, face edema, allergic reaction, abscess, chills, chills and fever, mucous membrane disorder; Rare: body odor, cyst, fever, hernia, abnormal BUN value, lump in neck, pelvic pain, sepsis, viral infection.

Cardiovascular System: Infrequent: hypertension, syncope, palpitation, migraine, hypotension, peripheral vascular disorder, cardiovascular disorder, cerebrovascular accident, congestive heart failure, myocardial infarction, vasodilatation; Rare: angina pectoris, heart failure, increased capillary fragility, phlebitis, thrombophlebitis, varicose vein.

Digestive System: Infrequent: gastroenteritis, increased appetite, gastrointestinal disorder, oral moniliasis, gastritis, tongue disorder, thirst, tooth disorder, abnormal stools, anorexia, liver function tests abnormal, periodontal abscess; Rare: cholecystitis, cholelithiasis, duodenal ulcer, fecal incontinence, gamma glutamyl transpeptidase increased, gingivitis, intestinal obstruction, intestinal ulcer, melena, mouth ulceration, rectal disorder, rectal hemorrhage, stomatitis.

Endocrine System: Infrequent: diabetes mellitus.

Hemic and Lymphatic System: Infrequent: ecchymosis, anemia; Rare: lymphadenopathy, lymphoma-like reaction, prothrombin decreased.

Metabolic and Nutritional: Infrequent: edema, gout, hypoglycemia, weight loss; Rare: alkaline phosphatase increased, diabetic ketoacidosis, lactic dehydrogenase increased.

Musculoskeletal: Infrequent: arthritis, arthralgia, myalgia, arthrosis, leg cramps, myasthenia; Rare: shin bone pain, joint disorder, tendon disorder.

Nervous System: Frequent: confusion, depression; Infrequent: vertigo, nervousness, paresthesia, insomnia, neuropathy, libido decreased, anxiety, depersonalization, reflexes decreased, speech disorder, abnormal dreams, dysarthria, emotional lability, nystagmus, stupor, circumoral paresthesia, euphoria, hyperesthesia, hypokinesia; Rare: agitation, hypertonia, libido increased, movement disorder, myoclonus, vestibular disorder.

Respiratory System: Infrequent: cough increased, bronchitis, rhinitis, sinusitis, pneumonia, asthma, lung disorder, epistaxis; Rare: hemoptysis, voice alteration.

Skin and Appendages: Infrequent: pruritus, skin ulcer, dry skin, herpes zoster, skin disorder, fungal dermatitis, furunculosis, herpes simplex, psoriasis, sweating, urticaria, vesiculobullous rash; Rare: acne, hair disorder, maculopapular rash, nail disorder, skin carcinoma, skin discoloration, skin hypertrophy.

Special Senses: Infrequent: abnormal vision, ear pain, eye disorder, taste perversion, deafness; Rare: conjunctival hyperemia, diabetic retinopathy, eye pain, fundi with microhemorrhage, retinal vein thrombosis, taste loss.

Urogenital System: Infrequent: urinary tract infection, dysuria, impotence, urinary incontinence, vaginal moniliasis, breast pain, menstrual disorder, polyuria, urinary retention; Rare: cystitis, ejaculation abnormal, swollen penis, gynecomastia, nocturia, pyelonephritis, swollen scrotum, urinary frequency, urinary urgency, urine abnormality.

Postmarketing and Other Experience

In addition to the adverse experiences reported during clinical testing of Gabapentin Capsules, the following adverse experiences have been reported in patients receiving marketed Gabapentin Capsules. These adverse experiences have not been listed above and data are insufficient to support an estimate of their incidence or to establish causation. The listing is alphabetized: angioedema, blood glucose fluctuation, erythema multiforme, elevated liver function tests, fever, hyponatremia, jaundice, movement disorder, Stevens-Johnson syndrome.

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

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Side Effects by Body System

Nervous system

Nervous system side effects have been common. Somnolence, dizziness, ataxia, headache, and fatigue have been reported to occur in more than 10% of treated patients. Vertigo, hyperkinesia, paresthesia, decreased or absent reflexes, increased reflexes, anxiety, and hostility have been reported frequently. CNS tumors, syncope, dreaming abnormal, aphasia, hypesthesia, intracranial hemorrhage, hypotonia, dysesthesia, paresis, dystonia, hemiplegia, facial paralysis, stupor, cerebellar dysfunction, positive Babinski sign, decreased position sense, subdural hematoma, apathy, hallucination, decrease or loss of libido, agitation, paranoia, depersonalization, euphoria, feeling high, doped-up sensation, suicide attempt, and psychosis have been reported infrequently. Choreoathetosis, orofacial dyskinesia, encephalopathy, nerve palsy, personality disorder, increased libido, subdued temperament, apraxia, fine motor control disorder, meningismus, local myoclonus, hyperesthesia, hypokinesia, mania, neurosis, hysteria, antisocial reaction, and suicide have been reported rarely. Nystagmus, tremor, nervousness, amnesia, dysarthria and depression have also been reported. A small number of cases of absence status and status epilepticus have occurred in patients taking gabapentin. Cases of delirium tremens have been reported upon gabapentin withdrawal.

Gastrointestinal

Gastrointestinal side effects have been reported in one to three percent of treated patients. Anorexia, flatulence, and gingivitis have been reported frequently. Glossitis, gum hemorrhage, thirst, stomatitis, increased salivation, gastroenteritis, hemorrhoids, bloody stools, and fecal incontinence have been reported infrequently. Dysphagia, eructation, pancreatitis, peptic ulcer, colitis, blisters in mouth, tooth discolor, perlèche, salivary gland enlarged, lip hemorrhage, esophagitis, hiatal hernia, hematemesis, proctitis, irritable bowel syndrome, rectal hemorrhage, and esophageal spasm have been reported rarely. Dyspepsia, dry mouth, constipation, dental abnormalities, flatulence, increased appetite, and weight gain have also been reported.

Other

Other side effects have been reported to include withdrawal effects. Withdrawal of gabapentin therapy has been reported to cause the following effects in less than 2% of treated patients: somnolence, ataxia, fatigue, nausea, vomiting, and dizziness.

Hearing loss, earache, tinnitus, inner ear infection, otitis, taste loss, unusual taste, ear fullness, perforated ear drum, sensitivity to noise, eustachian tube dysfunction, otitis externa, odd smell, and labyrinthitis have also been reported.

Hematologic

The patients reported to have decreased white blood cell counts were also taking carbamazepine.

Hematologic side effects have frequently been reported to include purpura. Anemia, thrombocytopenia, and lymphadenopathy have been reported infrequently. Increased WBC count, lymphocytosis, non-Hodgkin's lymphoma, and increased bleeding time have been reported rarely. Isolated cases of decreased white blood cell counts have also been reported.

Cardiovascular

Cardiovascular side effects including hypertension have been reported to occur in more than one percent of patients taking gabapentin. Hypotension, angina pectoris, peripheral vascular disorder, palpitation, tachycardia, and murmur have been reported infrequently. Atrial fibrillation, heart failure, thrombophlebitis, deep thrombophlebitis, myocardial infarction, cerebrovascular accident, pulmonary thrombosis, ventricular extrasystoles, bradycardia, premature atrial contraction, pericardial rub, heart block, pulmonary embolus, hyperlipidemia, hypercholesterolemia, pericardial effusion, and pericarditis have been reported rarely. A case of gabapentin induced edema has also been reported.

Ocular

Ocular side effects including abnormal vision have been reported frequently. Cataract, conjunctivitis, dry eyes, eye pain, visual field defect, photophobia, bilateral or unilateral ptosis, eye hemorrhage, hordeolum, eye twitching, diplopia and blurred vision have been reported infrequently. Eye itching, abnormal accommodation, eye focusing problem, watery eyes, retinopathy, glaucoma, iritis, corneal disorders, lacrimal dysfunction, degenerative eye changes, blindness, retinal degeneration, miosis, chorioretinitis, and strabismus have been reported rarely. A case of oculogyric crisis has also been reported.

Psychiatric

Psychiatric side effects including two cases of intolerable aggressive behavior have been reported. One case of hypomania has also been reported.

Dermatologic

Dermatologic side effects including alopecia, eczema, dry skin, increased sweating, urticaria, hirsutism, seborrhea, cyst, and herpes simplex have been reported infrequently. Herpes zoster, skin discolor, skin papules, photosensitive reaction, leg ulcer, scalp seborrhea, psoriasis, desquamation, maceration, skin nodules, subcutaneous nodule, melanosis, skin necrosis, and local swelling have been reported rarely. One case of alopecia and one case of leukocytoclastic vasculitis have been reported.

Hypersensitivity

Hypersensitivity side effects including a case of hypersensitivity syndrome have been reported.

Genitourinary

Genitourinary side effects including hematuria, dysuria, urination frequency, cystitis, urinary retention, urinary incontinence, vaginal hemorrhage, amenorrhea, dysmenorrhea, menorrhagia, breast cancer, inability to climax, and abnormal ejaculation have been reported infrequently. Kidney pain, leukorrhea, pruritus genital, renal stone, acute renal failure, anuria, glycosuria, nephrosis, nocturia, pyuria, urination urgency, vaginal pain, breast pain, and testicle pain have been reported rarely.

Musculoskeletal

Musculoskeletal side effects including arthralgia have been reported frequently. Tendinitis, arthritis, joint stiffness, joint swelling, and positive Romberg test have been reported infrequently. Costochondritis, osteoporosis, bursitis, and contracture have been reported rarely. Myoclonus has also been reported.

General

General side effects have included asthenia, malaise, and facial edema which have been reported frequently. Generalized edema, weight decrease, and chill have been reported infrequently. Lassitude, "strange feelings", alcohol intolerance, and hangover effect have been reported rarely.

Endocrine

Endocrine side effects including hyperthyroid, hypothyroid, swollen testicle, goiter, hypoestrogen, ovarian failure, epididymitis, and cushingoid appearance have been reported rarely.

Respiratory

Respiratory side effects including pneumonia have been reported frequently. Epistaxis, dyspnea, and apnea have been reported infrequently. Mucositis, aspiration pneumonia, hyperventilation, hiccup, laryngitis, nasal obstruction, snoring, bronchospasm, hypoventilation, and lung edema have been reported rarely.

Hepatic

Hepatic side effects including hepatomegaly have been reported infrequently. Several cases of hepatotoxicity have also been reported.

Oncologic

Male rats receiving doses of gabapentin of up to 2000 mg/kg for 2 years have developed acinar cell carcinoma of the pancreas.

Oncologic side effects have been reported in animal studies.

Renal

Renal side effects including two cases of marked increase in serum creatinine measurements following the introduction of gabapentin have been reported.

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