How long does 100mg of gabapentin take to work for pain? The onset of action for 100mg of gabapentin can vary depending on individual factors. Generally, gabapentin may start working within 1 to 2 hours after ingestion, with its peak effects typically achieved within 2 to 3 hours. However, the full pain-relieving effects may take a few days to a week to be fully realized as the medication needs time to build up in the body. It is essential to follow the prescribed dosage and dosing schedule provided by a healthcare professional to ensure optimal pain management and minimize the risk of side effects associated with gabapentin. visit:https://healthcurepills.com/product/gabapentin-100mg/