Did Gabapentin Help Unexplained Pelvic Pain in GaPP2?

A prescription review should start with the condition being treated. Chronic pelvic pain without an obvious surgical finding, pain from an identified disease and touch-provoked vulvar pain are different clinical questions.

What did GaPP2 test?

The UK double-blind trial randomized 306 women with pelvic pain lasting at least three months and no obvious pathology at laparoscopy. Eligible ages were 18–50; pain occurring only during periods was excluded. Gabapentin was increased as tolerated, up to 2,700 mg daily, over a 16-week course.¹

At weeks 13–16, adjusted gabapentin–placebo differences were −0.20 points for worst pain and −0.18 for average pain, on 0–10 scales. The 97.5% confidence intervals were −0.81 to 0.42 and −0.71 to 0.35, respectively, excluding the prespecified one-point meaningful benefit. About 80% supplied primary outcome data.¹

Serious adverse events affected 10/153 versus 3/153 women; these were not necessarily drug-caused. Dizziness, drowsiness and visual disturbances were more common with gabapentin. UK public funding supported the trial.¹

How does that affect a prescribing discussion?

The result concerns the population enrolled. It does not establish how to treat every cause of pelvic pain or replace a diagnosis. Our vulvodynia trial review covers a separate experiment using extended-release gabapentin for localized, touch-provoked vulvar pain.

If your clinician diagnoses chronic primary pain, NICE² recommends against starting gabapentinoids for that purpose. Chronic primary pain and pain attributable to an underlying condition can coexist; the guidance calls for clinical judgment when they do.²

For someone already taking these medicines, NICE² recommends reviewing benefit and harm together. It allows a shared plan to continue safely when benefit occurs at a safe dose with few harms, or supported reduction when benefit is small or harms substantial.²

Bring your current dose, the changes you have noticed and the activities pain still prevents. Ask which diagnosis supports the prescription and what would justify continuing it.

Should you stop because of this result?

Do not stop gabapentin abruptly. The US Neurontin label calls for gradual reduction over at least one week, sometimes longer at the prescriber’s discretion. It warns about withdrawal effects and serious breathing suppression with opioids, other sedating medicines or underlying breathing impairment. Mention these combinations and any excessive sleepiness at the review.³

The UK’s January 2026 MHRA update emphasizes individualized tapering; reducing a high dose can take weeks or months. Physical dependence does not automatically mean addiction. Ask the prescriber for the schedule appropriate to your prescription.⁴

Down There, Decoded includes “When Sex Hurts,” with prompts to record where pain occurs, its triggers, duration and how long it has persisted. Use those details to prepare the assessment conversation. See the book.