"I hear this all the time," says New York dermatologist Debra Jaliman, M.D., author of "Skin Rules." Proponents of the sunscreen-cancer link say that oxybenzone, an active ingredient in chemical sunscreens, creates free radicals, which, in theory, cause melanoma.

Engelman and Jaliman both say there isn't proof that sunscreen causes cancer; on the other hand, there is a lot of evidence that sun protection prevents it.

If certain ingredients make you wary, Engelman recommends physical sunscreen over chemical sunscreen. Physical sunscreen, containing ingredients like zinc oxide and titanium dioxide, forms a layer of protection over your skin to block sunlight, whereas chemical sunscreen sinks into your skin and absorbs UV light. "There is nothing more organic than zinc and titanium," points out Engelman. "They're on the periodic table."

"Patients think [skin care] products are magic potions," says board-certified dermatologist Jessica Krant, M.D. and founder of Art of Dermatology. "They use something for a week, but stop because they think it's not doing anything." Krant says good products take months (or more) to produce results that might not even be visible to the naked eye.

"Some work so subtly that they really only slow aging, so to you it seems like nothing is happening. You'd only be able to tell [the difference] if you could look at yourself 10 years in the future: One version of you having used the product, and one not."

And by "something," patients usually mean 10 different suspicious spots on their body, says Engelman. Often, patients don't want to do a full body check because they're embarrassed to undress or don't have time, but a single spot check is not even effective for the one funny-looking mole you're pointing out, Engelman stresses. "I need to be able to assess every mole and take into consideration the kind of moles a body produces." She says that a single mole might look normal at first glance, but if it looks nothing like the other moles on your body, it might be a problem.

Plus, unless you're a seriously bendy gymnast, you simply can't see areas of your body like the upper back or the backs of the knees -- and even if you are, you might not recognize what you see as dangerous. "The cancerous moles are never the ones patients point out to me," says Jaliman. "It's always something they didn't think looked bad, or couldn't see."

"It's always, 'one more thing,' as I'm walking out the door," laughs Jaliman. "That 'one last thing' usually takes up another hour."

Engelman says patients stop her as she's leaving with the phrase, "Oh, and I'm losing my hair."

"That'd be like stopping your general practitioner after he's given you a checkup, saying, 'One last thing -- I've been having some chest pains.' It's not going to be a quick diagnosis. Your GP would need to evaluate you, run tests, ask questions. It's the same for hair loss," says Engelman.

The best thing to do is tell the nurse upfront all the things you're in for, so the doctor can devote time to the issue and not be rushed, says Engelman.

"Some patients would rather listen to a hippie in Oregon who's made their own patchouli paste than take my recommendation," says Engelman, who says that some patients tell her they don't believe in Western medicine. "It makes me wonder, 'why are you here?' I went to school for 13 years to be a skin specialist, but some people think whatever they read on the Internet is doctrine," she says.

The Internet can be a great resource, but Jaliman says it's pointed more than one of her patients in the wrong direction.

"I had one patient who tried to do an at-home lemon peel, but used a high concentration of lemon juice. Lemon is highly acidic and will burn your face if you expose it to sunlight, causing a lot of brown discoloration. She probably spent $1 on the lemon, but ended up spending $2,000 on laser procedures to fix the damage," recalls Jaliman.