"Creams and pills do not work by telepathy through their containers from the bathroom countertop," says Krant. A lot of patients nod and tell their dermatologist they did everything they were told, but face washes go unused and pills go untaken.

Jaliman says that sometimes she finds out patients don't even fill their prescriptions, but they're embarrassed to tell her. "It makes me hesitate to give someone something else if I think they haven't been using the first thing I gave them. Something stronger might end up ruining their skin."

And another thing -- the strong stuff isn't always the best. "I give my patients what I think will be best for them the first time around," says Engelman. She says that if a patient doesn't use a medicine correctly and wants something else, it's not going to be as good as the initial prescription. "I'm not hiding more powerful stuff in the back."

Let's be clear about one thing: It's very obvious to dermatologists when someone has been a little too hands-on with a skin issue.

"Please don't do surgery on yourself in your bathroom," says Krant. Your bathroom, says Krant, is where little pimples become scars, sun damage becomes infected skin, and mild skin fungus turns into tinea incognito, a deep and spreading mess.

Perhaps the worst outcome of self-inflicted surgery is when people cut off their own skin tags and moles, says Jaliman. "The results are terrible, and leave a lot of scarring." Plus, even if you do manage to cut off the growth (a difficult feat, since cancer cells can wrap around surrounding nerves), those cells need to be looked at under a microscope in a lab, says Engelman. Under the scrutiny of a professional, cancer cells can often be traced to their origin in the body -- meaning a doctor can tell you if you have cancer elsewhere that needs to be addressed immediately.