Neurontin (Gabapentin): Nerve Pain, Seizures and Safety

What the 300 mg capsule treats

Neurontin 300 mg is an oral hard capsule containing gabapentin. The reviewed US label covers postherpetic neuralgia in adults and add-on treatment of partial-onset seizures. The UK label also covers adult peripheral neuropathic pain, including painful diabetic neuropathy, and has different epilepsy age and monotherapy provisions. Approval for a particular condition or age must therefore be checked locally. This capsule profile should not be used as a conversion guide for other gabapentin formulations.

Common effects and ongoing monitoring

Sleepiness, dizziness, unsteadiness, fatigue and peripheral swelling are important effects. Driving or operating machinery may be unsafe until the individual response is known. Gabapentin is cleared through the kidneys; kidney impairment can increase exposure and requires a professional review of treatment. New depression, unusual behaviour or suicidal thoughts need prompt clinical attention. These symptoms can also be reported after discontinuation, so follow-up is relevant when treatment changes as well as when it starts.

Interactions and withdrawal precautions

Opioids such as morphine and other sedating medicines can increase sedation and the risk of respiratory depression. Underlying lung or breathing problems increase concern. Alcohol can worsen impairment. Aluminium- or magnesium-containing antacids reduce gabapentin absorption; a pharmacist can explain the separation required by the product leaflet without changing the prescribed regimen. Dependence and withdrawal can occur. Abrupt stopping or rapid reduction may increase seizure frequency and cause additional withdrawal symptoms; an individual discontinuation plan is needed rather than a schedule copied from a website.

Serious reactions and reproductive questions

A rash with fever, swollen glands or signs of organ illness may represent a severe hypersensitivity reaction; urgent assessment is needed even if the rash is not striking. Face or throat swelling, breathing difficulty, inability to wake normally or collapse are emergencies. Tell the prescriber promptly about pregnancy, pregnancy plans or breastfeeding. Gabapentin enters breast milk, and treatment decisions must consider the condition being treated and the infant. For epilepsy, changing medicine without professional support can itself create serious risk; this summary does not determine whether treatment should continue.

Sources and scope

• Neurontin 300 mg hard capsules - UK Summary of Product Characteristics - Text revised February 2026; emc updated 13 April 2026
• Neurontin gabapentin - US prescribing information and Medication Guide - US label revised April 2025; DailyMed updated 12 May 2026

Source check: 30 October 2026. This records a source check, not a clinical review by a doctor or pharmacist. This summary does not replace the current leaflet supplied with your medicine or an individual treatment review.