It depends in part on how large an area it is applied to (exposure dose) and tends to run in families.

I used to use it all the time as an initial application on cuts and packed ingrown toenails with it. The last time I used it was when the dermatologist told me to use Vaseline where he had removed a mole. Applied it to an area about the size of a pencil eraser & put a band-aid over it. The next day, it had raised an itchy red/purple welt bigger than a quarter. Looking back, I had been showing more minor reactions to it for several years. Both my paternal grandfather and mother are allergic to it.

edit to add PS
P.S.
It's becoming more frequent to the point that the dermatologist told me when I saw him to find out what the reaction was that they had changed they're recommendation to Vaseline because of it.