| Drug Name: | Gabapentin / Neurontin |
| Dosage: | 100 – 800 mg |
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What are the most common adverse effects reported by patients taking gabapentin?
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At what dosage does gabapentin show the greatest effectiveness for chronic neuropathic pain?
Background
Gabapentin is widely prescribed for managing neuropathic pain caused by nerve damage. This publication updates earlier reviews from 2024, 2021, 2015, and 2010, reflecting the most recent evidence on its effectiveness.
Objectives
The aim of this review is to evaluate how effective gabapentin is in relieving chronic neuropathic pain in adults, as well as to examine its potential side effects.
Search Methods
To compile this update, researchers searched CENTRAL, MEDLINE, and Embase databases for randomized controlled trials published between January 2014 and January 2017. Additional sources included reference lists from relevant studies and reviews, along with online clinical trial registries.
Selection Criteria
Included studies were randomized, double-blind trials lasting at least two weeks. All compared gabapentin—regardless of how it was administered—with either a placebo or another active treatment. Pain levels were assessed based on participant self-reports.
Data Collection and Analysis
Two independent reviewers extracted the data and assessed the methodological quality of each trial, including risk of bias. The primary outcomes were the proportion of participants achieving substantial pain relief (defined as at least 50% reduction in pain from baseline or “very much improved” on the Patient Global Impression of Change [PGIC]) and moderate relief (at least 30% pain reduction or “much”/“very much improved” on PGIC). When possible, results were pooled to estimate overall treatment effects. Dichotomous data were used to calculate risk ratios (RR) and the number needed to treat (NNT) for one additional positive or negative outcome. The certainty of evidence was rated using GRADE methodology, and summary tables were prepared.
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| 270 pills | $0.57 | $68.45 | $222.23 $153.78 | |
| 360 pills | $0.55 | $97.78 | $296.31 $198.53 |
Main Results
The review included four new studies (530 participants) and excluded three previously included trials (126 participants). In total, 37 studies with 5,914 participants were analyzed. Most trials evaluated oral gabapentin or gabapentin enacarbil at daily doses of 1200 mg or more, targeting various forms of neuropathic pain—mainly postherpetic neuralgia and painful diabetic neuropathy. Study durations ranged from four to twelve weeks. Several studies did not report all relevant clinical outcomes. The main sources of bias were small sample sizes, especially in crossover trials, and poor handling of data following participant withdrawal.
In postherpetic neuralgia, 32% of participants receiving gabapentin (≥1200 mg/day) achieved substantial pain relief, compared to 17% on placebo (RR 1.8; 95% CI 1.5 to 2.1; NNT 6.7 [range 5.4–8.7]; 8 studies, 2260 participants; moderate-certainty evidence). Moderate relief was reported in 46% of the gabapentin group versus 25% of the placebo group (RR 1.8; 95% CI 1.6 to 2.0; NNT 4.8 [range 4.1–6.0]; 8 studies; moderate-certainty evidence).
Results in Painful Diabetic Neuropathy
In cases of painful diabetic neuropathy, 38% of participants taking gabapentin at a daily dose of 1200 mg or higher reported substantial pain relief (defined as at least 50% reduction in pain or “very much improved” on the PGIC scale), compared to 23% in the placebo group (RR 1.7; 95% CI 1.4 to 2.0; NNT 6.6 [range 5.0–10]; 6 studies, 1331 participants; moderate-certainty evidence). Moderate pain relief (≥30% reduction or “much”/“very much improved” on PGIC) was reported by 52% of those on gabapentin versus 37% on placebo (RR 1.4; 95% CI 1.3 to 1.6; NNT 6.6 [range 4.9–9.9]; 7 studies, 1439 participants; moderate-certainty evidence).
Adverse Events and Tolerability
Across all neuropathic pain conditions, withdrawals due to adverse effects occurred more frequently with gabapentin (11%) than with placebo (8.2%) (RR 1.4; 95% CI 1.1 to 1.7; NNH 30 [range 20–65]; 22 studies, 4346 participants; high-certainty evidence). Serious adverse events were reported at similar rates between groups—3.2% for gabapentin and 2.8% for placebo (RR 1.2; 95% CI 0.8 to 1.7; 19 studies, 3948 participants; moderate-certainty evidence). A total of eight deaths were reported, but the evidence quality was very low.
Mild to moderate side effects were more common with gabapentin: 63% of participants experienced at least one adverse event, compared to 49% on placebo (RR 1.3; 95% CI 1.2 to 1.4; NNH 7.5 [range 6.1–9.6]; 18 studies, 4279 participants; moderate-certainty evidence). The most frequently reported symptoms included dizziness (19%), drowsiness (14%), peripheral swelling (7%), and balance or gait problems (14%).
Authors’ Conclusions
Gabapentin, at doses ranging from 1800 mg to 3600 mg daily (or 1200 mg to 3600 mg for gabapentin enacarbil), may offer meaningful pain relief for some individuals with postherpetic neuralgia or painful diabetic neuropathy. Evidence supporting its use in other neuropathic conditions remains limited.
A reduction of 50% or more in pain intensity is often considered a clinically significant outcome by patients, typically associated with improvements in sleep, energy levels, mood, quality of life, daily functioning, and ability to work. Approximately 30% to 40% of those treated with gabapentin reached this level of pain relief, compared to 10% to 20% receiving placebo. However, more than half of patients may not achieve a meaningful benefit and could experience side effects. These conclusions remain consistent with previous versions of this review.
Introduction
Gabapentin is prescribed as monotherapy or as an add-on treatment for both simple and complex partial seizures in adults and children. In adults, it is also approved for the management of neuropathic pain. Beyond these approved indications, medical literature documents its potential benefits in a range of other clinical conditions.
Aim of the Study
This review aims to summarize current findings from the literature on the use of gabapentin in various fields of medicine, including toxicology, dermatology, gynecology, and psychiatry. The overview also highlights the potential for misuse or abuse of the drug.
Materials and Methods
A literature review was conducted using the PubMed database. Search terms were selected to identify studies evaluating the clinical use of gabapentin across different medical domains.
Results
Gabapentin is an anticonvulsant structurally related to gamma-aminobutyric acid (GABA). Although it is classified as a GABA analog, its mechanism of action differs from that of other GABAergic agents. Its approved uses include the treatment of partial seizures and neuropathic pain. Published data also report off-label applications, such as management of alcohol withdrawal symptoms, treatment of chronic itching (pruritus), relief of menopausal hot flashes, and use in anxiety disorders.
Summary
Gabapentin shows therapeutic potential across multiple medical areas. However, due to variability in reported outcomes and limited sample sizes in many studies, further research on larger patient populations is necessary to validate these findings and clarify its safety profile.