Do i really need to replaster a wall if rising damp is only 50mm above skirting? can i just inject the bricks?

I think i have a mild case of rising damp in my house which effects my gable wall, the water mark or tide mark is showing approx 50mm above my skirting and i want to know if i can just get away with injecting chemicals from the putside and do away with re-plastering as it is only 50mm, any ideas people?