I've always been told, or notice others being told, or hear it in popular media, that squeezing pimples or blackheads is somehow "bad" for you. Certainly, when there is a chance that the skin breaks, we have to worry about introducing infections and a whole host of other things.
What I wish to know is, can squeezing pimples cause any detrimental effect other than the obvious? Can the pimples mysteriously spread? Can one break out in a rash? Can one develop lumps under the skin?
Is there any kind of evidence to support the claim that squeezing pimples is bad for you?