How do I paint a peeling particle board bathroom vanity?

Peeling paper off will cause a bigger problem. The vanity is deteriorating due to moisture or water damage. It really should be replaced. But in mean time remove any loose paper and try to sand down. May crumble but try, paint with oil based primer, (not latex, don't need to add any more water to cabinet) lightly sand any rough areas, paint 2 coats of oil based paint.

Good luck.

Hi Elizabeth. I'm Cindy. The contact paper really should be removed. Put your hair drier on it's highest setting. Hold it a couple inches from the paper. Continually move it over the entire area that you want to remove. Carefully peel off the contact paper as you heat it until all of it comes off. After that sand it and paint it. Good luck Elizabeth. Happy holidays.

Cut off any lifting paper. Sand the edges smooth. Prime with Kilz primer. Then paint you color. You can use acrylic latex paint. Then seal with at least three coats of a water based polyurethane to protect the finish..

It is difficult to get paint to adhere to a slick surface. If the plastic won't peel off you may need to rough it up with a sander. Contact paper and its adhesive can really gum up your sandpaper. Once you get it all off, remember that particle board is very porous and will just suck up the paint. You will need to use specific primers as an undercoat. Check out the websites below for information on using primers before painting.

Laminate:

http://www.washingtonpost.com/wp-dyn/content/article/2005/09/21/AR2005092100593.html

Contact Paper:

https://www.naturalhandyman.com/qa/qapaintcontactpaper.html