Introduction Severe sialorrhoea is a common, distressing problem in children/adolescents with neurodisabilities, which has adverse health and social consequences. The SALIVA trial is designed to evaluate the efficacy and safety of a paediatric-specific oral solution of glycopyrronium along with its impact on quality-of-life (QoL), which has been lacking from previous trials of sialorrhoea treatments. Methods and analysis A double-blind, placebo-controlled, randomised phase IV trial is ongoing in several centres across France. Eighty children aged 3–17 years with severe sialorrhoea (≥6 on the modified Teachers Drooling Scale) related to chronic neurological disorders in whom non-pharmacological standard of care has already been implemented or has failed, will be recruited. Patients will be randomised 1:1 to receive a 2 mg/5 mL solution of glycopyrronium bromide (Sialanar 320 µg/mL glycopyrronium) or placebo three times daily during a 3-month blinded period. After Day 84, participants will be invited into a 6-month, open-label study extension period, where they will all receive glycopyrronium. The primary endpoint of the double-blind period will be the change from baseline to Day 84 in the Drooling Impact Scale (DIS), a validated measure to assess sialorrhoea. A series of secondary efficacy endpoints involving change in total DIS, specific DIS items and response (DIS improvement ≥13.6 points) will be analysed in a prespecified hierarchy. QoL data will be collected from parents, caregivers and patients where possible using specific DIS questions and DISABKIDS questionnaires. Safety endpoints, including adverse events, will be assessed throughout the trial periods. Ethics and dissemination In total, 87 children have been recruited and recruitment is now complete. Final results are expected by the end of 2023. Findings will be presented at conferences and published in peer-reviewed journals. Trial registration number EudraCT 2020-005534-15