A multicenter randomized controlled trial across five Chinese hospitals tested whether transcutaneous auricular vagal nerve stimulation (taVNS) — a non-invasive ear-based neuromodulation technique — could improve chronic constipation in 106 adults. Patients received either real taVNS (tragus stimulation) or sham taVNS (earlobe stimulation) twice daily for 30 minutes over 4 weeks. The primary outcome — achieving three or more complete spontaneous bowel movements per week — was met by only 17% of the taVNS group versus 19% of the sham group, a non-significant difference. The trial was stopped early after an interim analysis confirmed futility. No serious adverse events occurred. The findings do not support 25 Hz taVNS as an effective standalone treatment for chronic constipation.
