get it all the time :(
once you have rinsed well with water to get rid of non imbedded (surface) fibres, then lightly wash with a green scotchbrite kinda scourer. Just enough to scratch...
If still itchy, sand the area with a 80grit ish as it will remove the top layer of skin and thus the fibres (as they don't penetrate far).
Then wash as above.
Single strand carbon fibres with RESIN on them, as a splinter, half an inch deep, different story.

