Does Gabapentin (Gabapentin) cause weight gain?

From the Guidelines

Gabapentin is associated with weight gain, and clinicians should select therapies least likely to cause weight gain among options with similar efficacy, as stated in a recent study published in JAMA in 2023 1. When considering the use of gabapentin, it is essential to weigh the potential benefits against the risk of weight gain. The mechanism behind gabapentin-related weight gain is not fully understood but may involve increased appetite, fluid retention, and decreased energy expenditure. Some key points to consider:

• Gabapentin is listed as one of the medications that can promote weight gain, along with other antiepileptics, antipsychotics, and antidepressants 1.
• The risk of weight gain associated with gabapentin can be mitigated by selecting the lowest effective dose and monitoring weight trajectory closely 1.
• Alternative medications with lower risk of weight gain, such as pregabalin, may be considered in some cases, depending on the condition being treated 1.
• Lifestyle modifications, including dietary changes and regular exercise, can also help minimize the risk of weight gain associated with gabapentin use 1. In clinical practice, the decision to use gabapentin should be made on a case-by-case basis, taking into account the individual patient's risk factors for weight gain and the potential benefits of the medication. Clinicians should counsel patients on the risk of weight gain and monitor their weight trajectory closely when prescribing gabapentin, as recommended in a study published in Diabetes Care in 2025 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 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. Metabolic and Nutritional Disorders Peripheral edema 8 2 Weight gain 2 0 TABLE 4 Adverse Reactions in Pooled Placebo-Controlled Add-On Trials In Epilepsy Patients >12 years of age Body System/ Adverse Event GabapentinaN=543 % Placeboa N=378 % Body As A Whole Fatigue 11 5 Weight Increase 3 2

Weight gain is listed as an adverse reaction in the drug label, with an incidence of 2% in postherpetic neuralgia patients and 3% in epilepsy patients >12 years of age 2.

From the Research

Gabapentin and Weight Gain

• Gabapentin is associated with weight gain, although the exact mechanisms are not fully understood 3
• A study on pregabalin, a similar medication, found that one in six patients gained ≥7% weight from baseline, and generally exceeded 7%, 2-12 months after treatment onset 4
• Another study found that gabapentin and pregabalin were both effective in reducing pain score, but onset of pain relief was relatively faster with pregabalin, and weight gain was observed only with the use of pregabalin 5

Comparison with Pregabalin

• Pregabalin is known to cause weight gain, with a study finding that overall weight gainers experienced 1-year weight gain (median [% change]) of +6.20 kg [+9.12%] and 5.46 kg [+13.9%] 4
• A comparison of gabapentin and pregabalin found that both medications were effective in treating fibromyalgia, but pregabalin was associated with more adverse events, including weight gain 6

Clinical Efficacy and Tolerability

• A study on the clinical efficacy and tolerability of gabapentinoids found that dizziness, drowsiness, and somnolence were frequent adverse effects, and weight gain was observed only with the use of pregabalin 5
• The study also found that gabapentin and pregabalin were both effective in reducing pain score, but the onset of pain relief was relatively faster with pregabalin 5

Real-World Evidence

• A review of real-world evidence on the utilization, clinical and comparative effectiveness, and adverse effects of newer weight-loss therapies did not provide direct evidence on gabapentin and weight gain, but highlighted the importance of considering individual patient factors, such as the ability to stick to treatment plans and manage side effects 7