A loose implant is never normal, but it is often the crown or the abutment screw rather than the implant itself, and those can usually be re-tightened or replaced.
Movement of the implant in the bone is more serious and may need removal. Avoid chewing on it and book a check promptly.
A healthy dental implant should feel exactly like a natural tooth — completely solid, with no movement at all. So if your implant crown moves when you chew, rocks when you touch it, or makes a slight clicking sound, something needs attention. The important thing to understand is that "a loose implant" is not always the implant itself. An implant restoration has several components, and in many cases the loose part is repairable without touching the implant in your bone.
This guide explains the three places looseness can come from, how to tell how urgent your situation is, and what your dentist will do at each step. If you suspect the implant itself has failed, our guide to the signs of a failed dental implant covers the wider picture, and our dental implant removal (explant) service page explains what happens when an implant does need to come out.