Some people use the towel bar in their bathroom simply for displaying decorative towels or towel sets. If you use the towel bar in your bathroom this way, you will probably never have any problems with it. If you use your towel bar for air drying heavy, damp towels, then sooner or later the screws in the towel bar will become loose, causing the towel bar to wobble or even fall from the wall.
Tightening Your Towel Bar
A towel bar usually comes loose because the screws have failed. The screws for your towel bar are usually found under the end holder piece on either end of the towel bar. On some towel bars, you can actually see the screws that hold the bar in place. Others have a decorative cover that hides the screws.
Most the time, simply taking a screwdriver and tightening the screws will re-secure the towel bar and keep it from wobbling or coming loose. In the event that tightening the screws does not help, you may need to remove the wall mounts and reinstall the towel bar.