Kitchens and bathrooms are both high moisture areas, especially if your bathroom has a lack of ventilation and airflow. If your bathroom does not have a fan or window, paint failure is almost bound to happen. Common ways to combat high moisture areas and keep them dry include:
Having good sources of ventilation like a high powered vent in bathrooms without a window. Opening windows in smaller bathrooms will also help to prevent moisture build-up
Upgrading bathroom wall and ceiling paint to a high-grade latex enamel or paint
Adding mildewcide to paint and primer to ensure mold blocking