Gabapentin (Neurontin)

What it's used for

Neuropathic pain (diabetic neuropathy, postherpetic neuralgia after shingles), partial seizures (as add-on therapy), restless legs syndrome, and sometimes off-label for anxiety, fibromyalgia, and alcohol withdrawal.

Typical dosing (adults)

• Neuropathic pain starting: 300 mg on day 1, 300 mg twice daily on day 2, 300 mg three times daily on day 3 (gradual titration).
• Effective range: 900–3,600 mg daily in three divided doses.
• Seizures: 900–1,800 mg daily in three divided doses.
• Doses must be reduced in kidney disease. Do not stop abruptly — taper gradually.

Key interactions

• Opioids (morphine, oxycodone, hydrocodone): major — increased risk of severe drowsiness and respiratory depression.
• Antacids (aluminum/magnesium-based): moderate — reduce gabapentin absorption by up to 20%; take gabapentin at least 2 hours after antacids.
• Alcohol: major — increased drowsiness, dizziness, and impaired coordination.
• Other CNS depressants (benzodiazepines, sleep aids): major — additive sedation and breathing risk.
• Morphine: moderate — morphine increases gabapentin blood levels.

Common side effects

Drowsiness and dizziness (very common, especially early on), fatigue, blurred vision, weight gain, swelling of hands/feet (peripheral edema), and unsteadiness. Most side effects improve after the first few weeks. Rare: mood changes, suicidal thoughts (FDA warning for all anticonvulsants).

Who should be cautious

• Kidney disease (dose must be reduced based on creatinine clearance).
• Elderly (higher risk of falls due to dizziness).
• History of substance use disorder (gabapentin misuse potential is recognized).
• Respiratory disease, especially if also taking opioids.

What to ask your pharmacist

• How quickly can I increase my dose if the pain is not controlled?
• Can I take gabapentin with my antacid or calcium supplement?
• What happens if I miss a dose — should I double up?
• How long does it take to feel the full pain-relief effect?