Commonly reported side effects of gabapentin include: ataxia, dizziness, drowsiness, fatigue, fever, nystagmus disorder, sedated state, and viral infection. Other side effects include: blurred vision, diplopia, peripheral edema, tremor, amblyopia, irritability, and xerostomia. See below for a comprehensive list of adverse effects.

Applies to gabapentin: oral capsule, oral solution, oral suspension, oral tablet

Along with its needed effects, gabapentin may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking gabapentin:

More common

• Clumsiness or unsteadiness
• continuous, uncontrolled, back-and-forth, or rolling eye movements

More common in children

• Aggressive behavior or other behavior problems
• anxiety
• concentration problems and change in school performance
• crying
• depression
• false sense of well-being
• hyperactivity or increase in body movements
• rapidly changing moods
• reacting too quickly, too emotional, or overreacting
• restlessness
• suspiciousness or distrust

Less common

• Black, tarry stools
• chest pain
• chills
• cough
• depression, irritability, or other mood or mental changes
• fever
• loss of memory
• pain or swelling in the arms or legs
• painful or difficult urination
• shortness of breath
• sore throat
• sores, ulcers, or white spots on the lips or in the mouth
• swollen glands
• unusual bleeding or bruising
• unusual tiredness or weakness

Incidence not known

• Abdominal or stomach pain
• blistering, peeling, or loosening of the skin
• clay-colored stools
• coma
• confusion
• convulsions
• dark urine
• decreased urine output
• diarrhea
• dizziness
• fast or irregular heartbeat
• headache
• increased thirst
• itching or skin rash
• joint pain
• large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or sex organs
• loss of appetite
• muscle ache or pain
• nausea
• red skin lesions, often with a purple center
• red, irritated eyes
• unpleasant breath odor
• vomiting of blood
• yellow eyes or skin

Some side effects of gabapentin may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

• Blurred vision
• cold or flu-like symptoms
• delusions
• dementia
• hoarseness
• lack or loss of strength
• lower back or side pain
• swelling of the hands, feet, or lower legs
• trembling or shaking

Less common or rare

• Accidental injury
• appetite increased
• back pain
• bloated or full feeling
• body aches or pain
• burning, dry, or itching eyes
• change in vision
• change in walking and balance
• clumsiness or unsteadiness
• congestion
• constipation
• cough producing mucus
• decrease in sexual desire or ability
• difficulty with breathing
• dryness of the mouth or throat
• earache
• excess air or gas in the stomach or intestines
• excessive tearing
• eye discharge
• feeling faint, dizzy, or lightheadedness
• feeling of warmth or heat
• flushed, dry skin
• flushing or redness of the skin, especially on the face and neck
• frequent urination
• fruit-like breath odor
• impaired vision
• incoordination
• increased hunger
• increased sensitivity to pain
• increased sensitivity to touch
• increased thirst
• indigestion
• noise in the ears
• pain, redness, rash, swelling, or bleeding where the skin is rubbed off
• passing gas
• redness or swelling in the ear
• redness, pain, swelling of the eye, eyelid, or inner lining of the eyelid
• runny nose
• sneezing
• sweating
• tender, swollen glands in the neck
• tightness in the chest
• tingling in the hands and feet
• trouble sleeping
• trouble swallowing
• trouble thinking
• twitching
• unexplained weight loss
• voice changes
• vomiting
• weakness or loss of strength
• weight gain

Applies to gabapentin: compounding powder, oral capsule, oral solution, oral tablet, oral tablet extended release

Common (1% to 10%): Peripheral edema, vasodilation, hypertension

Rare (less than 0.1%): Atrial fibrillation, heart failure, myocardial infarction, cerebrovascular accident, ventricular extrasystoles, bradycardia, premature atrial contraction, pericardial rub, heart block, pericardial effusion, pericarditis

Postmarketing reports: Cardiac arrest, chest pain, palpitation, tachycardia

Common (1% to 10%): Abrasion, facial edema, purpura, rash, pruritus, acne

Uncommon (0.1% to 1%): Alopecia, eczema, dry skin, increased sweating, urticaria, hirsutism, seborrhea, cyst, herpes simplex

Rare (less than 0.1%): Stevens-Johnson syndrome, angioedema, erythema multiforme, drug rash (with eosinophilia and systemic symptoms), herpes zoster, skin discolor, skin papules, photosensitive reaction, psoriasis, desquamation, maceration, skin nodules, subcutaneous nodule, melanosis, skin necrosis, local swelling

Frequency not reported: DRESS/multiorgan hypersensitivity

Rare (less than 0.1%): Hyperthyroid, hypothyroid, goiter, hypoestrogenism, ovarian failure, epididymitis, cushingoid appearance

Common (1% to 10%): Diarrhea, dry mouth or throat, constipation, nausea, vomiting, dyspepsia, dental abnormalities, gingivitis, abdominal pain, flatulence

Uncommon (0.1% to 1%): Glossitis, gum hemorrhage, thirst, stomatitis, increased salivation, gastroenteritis, hemorrhoids, bloody stools, fecal incontinence

Rare (less than 0.1%): Pancreatitis, dysphagia, eructation, pancreatitis, peptic ulcer, colitis, blisters in mouth, tooth discoloration, perlèche, salivary gland enlarged, lip hemorrhage, esophagitis, hiatal hernia, hematemesis, proctitis, irritable bowel syndrome, rectal hemorrhage, esophageal spasm

Frequency not reported: Dehydration

The most common adverse reactions associated with the use of this drug were dizziness, somnolence, and peripheral edema.

Common (1% to 10%): Incontinence, impotence

Uncommon (0.1% to 1%): Hematuria, dysuria, urinary frequency, cystitis, urinary retention, vaginal hemorrhage, amenorrhea, dysmenorrhea, menorrhagia

Frequency not reported: Breast hypertrophy, gynecomastia, sexual dysfunction (including changes in libido, ejaculation disorders, and anorgasmia)

Common (1% to 10%): Leucopenia, purpura

Uncommon (0.1% to 1%): Anemia, lymphadenopathy

Rare (less than 0.1%): Thrombocytopenia, thrombophlebitis, leukocytosis, lymphocytosis, increased bleeding time

Frequency not reported: Blood creatine phosphokinase increased, coagulation defect

Rare (less than 0.1%): Hepatitis, jaundice, elevated liver function tests SGOT (AST), SGPT (ALT), and bilirubin, hepatomegaly, hepatotoxicity

Very rare (less than 0.01%): Hypersensitivity syndrome, a systemic reaction with a variable presentation that can include fever, rash, hepatitis, lymphadenopathy, eosinophilia, and sometimes other signs and symptoms

Common (1% to 10%): Weight gain, hyperglycemia

Postmarketing reports: Hyponatremia

Common (1% to 10%): Back pain, arthralgia, myalgia, twitching

Uncommon (0.1% to 1%): Tendonitis, arthritis, joint stiffness, joint swelling

Frequency not reported: Rhabdomyolysis, myoclonus

Postmarketing reports: Elevated creatine kinase, rhabdomyolysis

Very common (10% or more): Somnolence (21%), dizziness (17%), ataxia (13%)

Common (1% to 10%): Abnormal gait, incoordination, neuralgia, tremor, dysarthria, hyperkinesia, seizures, dysarthria, paresthesia, hypesthesia, coordination abnormal, increased/decreased/absent reflexes, vertigo

Uncommon (less than 1%): Hypokinesia

Rare (less than 0.1%): Movement disorders (e.g., choreoathetosis, dyskinesia, dystonia), loss of consciousness

Frequency not reported: Withdrawal precipitated seizure/status epilepticus

Postmarketing reports: Movement disorder

Common (1% to 10%): Amblyopia, conjunctivitis, diplopia, nystagmus

Uncommon (0.1% to 1%): Cataract, dry eyes, eye pain, visual field defect, photophobia, bilateral or unilateral ptosis, eye hemorrhage, hordeolum, eye twitching

Rare (less than 0.1%): Eye itching, abnormal accommodation, eye focusing problem, watery eyes, retinopathy, glaucoma, iritis, corneal disorders, lacrimal dysfunction, degenerative eye changes, blindness, retinal degeneration, miosis, chorioretinitis, strabismus

Uncommon (0.1% to 1%): Breast cancer

Rare (less than 0.1%): Non-Hodgkin's lymphoma

Very common (10% or more): Fatigue (11%), fever (11%)

Common (1% to 10%): Asthenia, accidental injury, otitis media, tremor, pain

Rare (0.01% to 0.1%): Tinnitus

Very rare (less than 0.01%): Sudden unexplained death in patients with epilepsy

Frequency not reported: Sleepwalking, withdrawal symptoms, 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, labyrinthitis

Common (1% to 10%): Abnormal thinking, amnesia, depression, hostility, confusion, emotional liability, anxiety, nervousness, insomnia

Uncommon (0.1% to 1%): Mental impairment

Rare (less than 0.1%): Hallucinations

Frequency not reported: Suicidal behavior and ideation, hypomania

Rare (less than 0.1%): Acute renal failure

Common (1% to 10%): Pharyngitis, dyspnea, cough, bronchitis, respiratory infection, rhinitis

Rare (less than 0.1%): Pulmonary thrombosis, pulmonary embolism

Frequency not reported: Pseudo-croup, hoarseness