If you have no fan or inadequate ventilation, steam from your daily shower will soften and degrade the paint and underlying drywall. High humidity and moisture is the most common reason bathroom paint peels. Painting over oil-based paint with water-based paint or painting over dirty walls also results in peeling paint, especially if you use budget-priced, low-quality paint. To stop paint peeling, you have to address both the immediate problem by preparing, priming and repainting, as well as the underlying cause of the peeling paint problem.
Remove everything possible from the bathroom, such as shower curtains, towel bars, clutter on the counter top and bathroom rugs. Depending on the extent of the peeling, this could be a messy job. Open windows or use fans for ventilation.
Scrape loose and peeling paint from the surface using a chisel-edged paint scraper.
Clean the walls and ceiling with mild cleanser and clean, lint-free rags or a sponge to remove hairspray, soap scum and fingerprints. The Paint Quality Institute recommends a mixture of three parts water to one part bleach to remove mildew.
Sand all painted surfaces with 120-grit sandpaper or a sanding sponge.
Prime the peeled areas with oil- or shellac-based stain-blocking primer. If the entire bathroom was peeling, prime the entire bathroom. Allow it to dry according to label directions and apply two coats of high-quality bathroom paint.
Turn on the bathroom vent fan every time you take a shower or use the bathroom. If you do not have a fan, keep the window or doors open or use a fan to direct the humid air out of a window or door.
Don't apply paint too thickly. This can contribute to peeling paint. Count on doing two thin, even coats over the primed surface.
Never use ammonia-based cleaners with bleach. You can create toxic chlorine gas. If your home was built before 1980, the bathroom may have been painted with lead-based paint. If you're not sure, call a professional who is certified in working with lead-based paint.