What are the side effects of Gabapentin (Neurontin)?

From the Guidelines

Gabapentin commonly causes side effects such as sedation and edema of the lower extremities, which are the most frequently reported adverse effects, as noted in a recent study published in the Mayo Clinic Proceedings 1.

Common Side Effects

The most common side effects of gabapentin include:

• Sedation
• Edema of the lower extremities
• Dizziness
• Drowsiness
• Fatigue
• Unsteadiness These side effects typically appear within the first few weeks of treatment and often diminish over time.

Serious Side Effects

More serious but rare side effects include:

• Mood changes
• Suicidal thoughts
• Severe allergic reactions
• Respiratory depression, particularly when combined with opioids or other central nervous system depressants

Management of Side Effects

Starting with a low dose (typically 100-300mg) and gradually increasing can help minimize side effects, as recommended in a study published in the Mayo Clinic Proceedings 1. Patients should never stop gabapentin abruptly as this can cause withdrawal symptoms; instead, the medication should be tapered slowly under medical supervision. Elderly patients and those with kidney problems may need lower doses as they're more susceptible to side effects, as noted in a study published in Diabetes/Metabolism Research and Reviews 1.

Mechanism of Action

Gabapentin works by modulating calcium channels in the nervous system, which explains its sedative effects.

Dosage Recommendations

The conventional dosing regimen for initiation of oral gabapentin is 300 mg 3 times daily, although alternative dosing regimens may be considered, and doses may be gradually increased to achieve the desired effect, as recommended in a study published in the Mayo Clinic Proceedings 1.

From the FDA Drug Label

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 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 Gabapentin may cause serious side effects including: suicidal thoughts or actions, changes in behavior and thinking, and serious or life-threatening allergic reactions The most common side effects of gabapentin tablets include: lack of coordination, viral infection, feeling drowsy, nausea and vomiting, difficulty with speaking, tremor, swelling, usually of legs and feet, feeling tired, fever, jerky movements, difficulty with coordination, double vision, unusual eye movement

Common side effects of gabapentin include:

• Dizziness
• Somnolence
• Peripheral edema
• Ataxia
• Fatigue
• Nystagmus
• Viral infection
• Fever
• Nausea and/or vomiting
• Hostility
• Lack of coordination
• Tremor
• Swelling
• Feeling tired
• Jerky movements
• Difficulty with coordination
• Double vision
• Unusual eye movement

Serious side effects of gabapentin include:

• Suicidal thoughts or actions
• Changes in behavior and thinking
• Serious or life-threatening allergic reactions 2 2 2

From the Research

Gabapentin Side Effects

• The side effects of gabapentin tend to be mild to moderate in intensity, most frequently affect the central nervous system, and resolve with time in many individuals 3.
• Common side effects associated with gabapentin include dizziness and somnolence, with a frequency of 21%-26% 4.
• Other side effects caused by gabapentin include teratogenicity, hypoventilation, respiratory failure, and myopathy 5.
• Gabapentin has been labeled category C on the basis of effects on rodent fetuses, and experience with use in pregnant women is limited 3.
• The medication is well tolerated, in general, but lack of significant binding to plasma proteins and lack of liver metabolism contribute to the absence of known limiting drug-drug interactions, particularly with other AEDs 3.

Comparison with Pregabalin

• Pregabalin showed superior results compared to gabapentin in the Visual Analog Scale (VAS) at various time intervals up to 12-14 weeks 6.
• Pregabalin resulted in lower opioid consumption and had a higher incidence of nausea and vomiting compared to gabapentin 6.
• Gabapentin had a higher incidence of dose reductions due to adverse effects compared to pregabalin 7.
• The average number of pills per day was higher in the gabapentin group compared to the pregabalin group 7.

Interactions and Contraindications

• Gabapentin has potential interactions with other drugs, including morphine, caffeine, losartan, ethacrynic acid, phenytoin, mefloquine, and magnesium oxide 5.
• Gabapentin is contraindicated in conditions such as myasthenia gravis and myoclonus 5.
• The risks of gabapentin misuse are increased due to the higher level of prescriptions, related fatalities, recreational misuse, and higher doses of self-administration 5.