You need to find the cause of the mould first. Once that issue is solved you will have to wait until the ceiling dries out. Remove the mould, then add a sealer and re paint.
I used this solution and it worked good for me.
Use a Borax solution for a natural mold remover. Borax is a natural insecticide and fungicide. Mix together 1 cup (204 g) of Borax with 1 US gal (3.8 L)of water and then pour the solution into a spray bottle. Simply spray the solution directly on the surface you want to clean. Borax doesn’t need to be rinsed off, as it can prevent more mold from growing in the future.
You can find Borax in the laundry section of grocery stores. It is a white mineral powder.
Borax is dangerous to consume, but unlike bleach, it doesn't release toxic fumes.
Hire a pro. Mold is not only deadly but insidious....much of it is not visible. Don't risk your health.
Hi Maria - There are several ways to get rid of mold, but most importantly, you need to address the root cause to keep it from returning. This article focuses on the bathroom, but is an overall great article that covers methods of how to remove mold, if bleach is safe to use, and how to prevent it from coming back. Hope this helps! Hugs, Holly
If just surface mold, vinegar is your go to. It kills mold spores.
If a serious infestation, then you need to call in the pros. To keep from recurring, install an exhaust fan, open a window or even a portable fan will work. One of my bathrooms has a window. It is never closed, always open at least a couple inches, and fully open when showering. The other bathroom is an interior with an exhaust fan. Not used often, so no issues there.