Can a registered nurse inject Botox or filler in Mississippi?

Short answer
Yes — an RN may administer medications and treatments prescribed by a licensed or legally authorized physician or dentist, as execution of the medical regimen; diagnosing and prescribing stay outside RN practice except as Board of Nursing rules provide.

The nursing sections cited here define each level of nursing by the order it follows and tie the advanced practice registered nurse to a collaborating physician. Registered-nurse practice includes executing the medical regimen, including administering medications and treatments prescribed by a licensed physician or dentist, and excludes medical diagnosis and prescribing except as the Board of Nursing provides by rule; licensed practical nursing is performed under the direction of a registered nurse, physician, or dentist using standardized procedures. An advanced practice registered nurse may diagnose, treat, and manage medical conditions and may hold prescriptive authority, but must practice in a collaborative/consultative relationship with a physician or dentist holding an unrestricted Mississippi license, within a board-approved protocol filed with the board, and may not practice as an APRN without that relationship and protocol; the Board of Nursing requires reliable communication with the collaborating physician and a formal collaborative agreement submitted before practice, and lets an authorized APRN prescribe Schedules II through V. Nurse practitioners may engage in that nursing practice without a physician’s license. The medical board files each collaboration and reviews protocols for practices more than seventy-five miles from the physician. Physician assistants are licensed and regulated by the medical board and supervised by a physician who practices in Mississippi at least twenty hours a week and is approved to supervise. None of the sections cited here mentions injectables, neuromodulators, or fillers by name.