what paint to use for rising damp?

[KatM]

I heard there is a specific paint to use for rising damp, when painting the plaster on walls. What specific paint or product is it? 

At what stage do you pop this on? I.e. do you do undercoat, top paint then rising damp paint? Or the other way around - rising damp paint, undercoat, top coat? 

Is it worth painting the whole house with this? Or even just the wet areas, e.g bathroom. The reason I ask is because my home is a 1939 home where there is minimal rising damp visible on the inside and not really any moisture (Ive had to checked), however the outter bricks, some mortar is coming off so I'm worried that down the track it may appear internally. Although I have lived in my place for 17 years now, it's been pretty good, but I will be renting my place out shortly so I also want to prepare and make sure it doesn't pop up when renters are in. TIA