Anticonvulsant / Neuropathic Analgesic Pregnancy: Should not be used during pregnancy unless the potential benefit to the mother clearly outweighs the potential risk to the foetus; gabapentin crosses the human placenta and neonatal withdrawal syndrome has been reported (risk increased with co-exposure to opioids). Excreted in human milk — use while breast-feeding only if benefits clearly outweigh risks.

Gabapentin

Brand names: Neurontin

Gabapentin is an antiepileptic and neuropathic-pain agent used for neuropathic pain and as adjunctive seizure therapy; in older people sedation, falls and renal dosing are central concerns.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: 900 mg daily in three divided doses, reached by titration (Day 1: 300 mg once daily; Day 2: 300 mg twice daily; Day 3: 300 mg three times daily), then increased if needed in 300 mg/day increments every 2-3 days

Route: Oral

Frequency: Three times daily — the total daily dose must be divided into three single doses and the maximum interval between doses should not exceed 12 hours

Max: 3600 mg/day

The same titration scheme applies to all indications in adults and adolescents aged 12 years and above. Epilepsy: effective dosing range in clinical trials was 900 to 3600 mg/day; therapy may start with the Day 1-3 titration or with 300 mg three times a day on Day 1. Minimum time to reach 1800 mg/day is one week, 2400 mg/day two weeks and 3600 mg/day three weeks; slower titration may be appropriate for individual patients. Peripheral neuropathic pain: start at 900 mg/day in three equally divided doses (or use the titration table) and increase in 300 mg/day increments every 2-3 days to a maximum of 3600 mg/day; efficacy and safety beyond 5 months of treatment have not been examined. ELDERLY: patients over 65 years may require dosage adjustment because of declining renal function with age (see renal dosing table) — somnolence, peripheral oedema and asthenia may be more frequent in elderly patients, and gabapentin-associated dizziness and somnolence could increase the occurrence of accidental injury (falls). In patients with poor general health (e.g. low body weight, after organ transplantation) titrate more slowly, using smaller dosage strengths or longer intervals between increases. Discontinuation should be gradual over a minimum of 1 week, whatever the indication. Plasma concentration monitoring is not required. Take with or without food, swallowed whole with sufficient fluid. Haemodialysis: for anuric patients never previously given gabapentin, a loading dose of 300 to 400 mg then 200 to 300 mg after each 4 hours of haemodialysis, with no treatment on dialysis-free days; renally impaired patients on haemodialysis take their Table 2 maintenance dose plus an additional 200 to 300 mg after each 4-hour session.

Paediatric dose

Route: Oral

Frequency: Total daily dose divided into three single doses; maximum interval between doses should not exceed 12 hours

Epilepsy, children aged 6 years and above (UK SPC): starting dose 10 to 15 mg/kg/day, with the effective dose reached by upward titration over approximately three days; effective dose 25 to 35 mg/kg/day. Dosages up to 50 mg/kg/day have been well tolerated in a long-term clinical study. Ranges rather than a single per-kg figure are given, so dosePerKg is left null. The US label in the bundle differs — it covers ages 3 to 11 years with 10 to 15 mg/kg/day starting, 40 mg/kg/day maintenance at 3 to 4 years and 25 to 35 mg/kg/day at 5 to 11 years. Verify against a children's formulary before use.

Dose adjustments

Renal

Dosage adjustment is required by creatinine clearance (total daily dose given in three divided doses): CrCl 80 mL/min or above, 900-3600 mg/day; 50-79 mL/min, 600-1800 mg/day; 30-49 mL/min, 300-900 mg/day; 15-29 mL/min, 150-600 mg/day (150 mg to be given as 300 mg every other day); below 15 mL/min, 150-300 mg/day, with the daily dose reduced in proportion to creatinine clearance (e.g. a patient with CrCl 7.5 mL/min receives half the dose of a patient with CrCl 15 mL/min).

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Hypersensitivity to gabapentin or to any of the excipients

Side effects

Somnolence, dizziness and ataxia (very common)
Viral infection (very common); pneumonia, respiratory infection, urinary tract infection, otitis media
Peripheral/facial oedema, fatigue and asthenia
Nausea, vomiting, diarrhoea, abdominal pain, dyspepsia, constipation and dry mouth
Confusion, emotional lability, depression, anxiety, nervousness and abnormal thinking; suicidal ideation and behaviour reported

Interactions

Opioids (morphine, hydrocodone, oxycodone, buprenorphine) and other CNS depressants — respiratory depression and sedation, sometimes fatal; observe closely for CNS depression
Hydrocodone exposure is decreased by co-administered gabapentin; consider when starting or stopping gabapentin
Antacids containing aluminium and magnesium hydroxide reduce gabapentin bioavailability by about 20% — take gabapentin at least 2 hours after the antacid
No appreciable interaction with commonly co-administered antiepileptic medicinal products; plasma level monitoring is not needed

Clinical monograph

How it works

It binds the alpha-2-delta subunit of voltage-gated calcium channels, reducing excitatory neurotransmitter release and modulating neuronal excitability.

Prescribing in practice

It is renally cleared, so reduce the dose in renal impairment common in older people, and titrate slowly to limit dizziness, sedation and falls.
Gabapentin is a controlled drug with potential for misuse and dependence; the combination with opioids increases the risk of respiratory depression and sedation.
Withdraw gradually to avoid withdrawal symptoms and, in epilepsy, the risk of rebound seizures.

Monitoring

Monitor for sedation, dizziness, mood changes and falls, and review renal function as a guide to dosing.

Counselling the patient

Drowsiness and dizziness are common at first; take care with driving and avoid falls.
Do not stop suddenly, as this can cause withdrawal effects.
Tell your team about opioid painkillers, as the combination can dangerously slow breathing.

Evidence & guidelines

MHRA guidance reclassified gabapentin as a controlled drug and warns of respiratory depression with concomitant opioids or in those with reduced respiratory reserve, including older patients.

Reference: NICE CG173 (Neuropathic Pain); MHRA Drug Safety Update 2017; AGS Beers Criteria 2023; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Drugs

Pathways