This manual summarizes key issues related to the safety of NTD medicines and their administration, with a focus on essential medicines used in mass drug administration (MDA), also called preventive chemotherapy. It can be used as a standalone reference manual, but is intended to be used in conjunction with the accompanying training modules, which provide practical instruction, and the aide-mémoires. Versions of the aide-mémoires and training modules are available respectively for both (i) programme managers and district-level health officials and (ii) community drug distributors and community health workers