<p>Thulium is a heavy lanthanide and the second-least abundant rare-earth element in the lanthanide series. Out of 35 isotopes of thulium, only two isotopes, ¹⁷¹Tm and ¹⁷⁰Tm, have relatively longer half-lives of 701 days and 128 days, respectively, and ¹⁶⁹Tm is the most stable isotope of thulium. The longest half-life of ¹⁷⁰Tm provides its logistical benefit to supply thulium worldwide without losing its activity. ¹⁷⁰Tm is expected to cause low bone marrow toxicity because it has lower beta energy than other radionuclides. Thulium can be a promising radionuclide for bone pain palliation, considering its half-life as well as beta and gamma radiation. A thulium-based laser is used in the resection of tumours and has limited application as a diagnostic agent in the military, medicine, and meteorology. The well-tolerated dose of the thulium-EDTMP complex is 370 MBq in a patient having bone pain associated with skeletal metastasis. This article aims to review and discuss the current state of knowledge on the ecotoxicological, toxicological, and pharmacological properties of thulium and provide a foundation for further research on thulium as a bone pain palliator.</p>