8 bad skin habits they'll shock you

8 BAD SKIN HABITS THEY'LL SHOCK YOU

SKIN SIN NO. 1: NOT USING OIL ON YOUR FACE

Does simply hearing the word "oil" make you break out? While you may balk at the idea of applying oil on your face -- especially if you have oily skin -- using it can actually decrease your skin's oil production. Sounds crazy, but hear us out: Over-cleansing stimulates the sebum glands, which prompts more oil production, says Lori Cahitas, an esthetician for Murad, Inc. in Los Angeles. Introducing oil to the skin can have the opposite effect and actually slow oil production, making you less shiny. And contrary to popular belief, face oils can even improve acne. "Essential oils are anti-bacterial and anti-fungal, so they're very good at killing bacteria that's causing the breakouts."

Keep in mind that using oil on your face isn't just beneficial for those with oily skin; even normal and mature skin can benefit from this skin care habit. The key is to get high quality oil with a "molecular structure that's so small it can penetrate into your skin without sitting on top and clogging your pores," says Cahitas. One we love: Eve Taylor Essential Oils, $29.50. Use it after you cleanse at night, when you don't mind looking a little greasy.

sKIN SIN NO. 2: EATING DAIRY AND OTHER INFLAMMATORY FOODS

Turns out that glass of milk your mother may have forced you to drink as a kid may actually be harmful to your skin and health. Dr. Jessica Wu, M.D., Los Angeles-based dermatologist and author of "Feed Your Face" says cow's milk -- even organic -- contains its own hormones and growth factors that are absorbed into the bloodstream. These hormones have androgenic effects that can cause acne in women. Dairy products are also pro-inflammatory, which means they can worsen acne issues and also accelerate aging, says dermatologist Nicholas Perricone, M.D. So find your calcium in other forms, such as dark leafy greens and tofu.

Speaking of tofu and other protein-packed foods, it's a good idea to limit your consumption of protein and not consume more than one type at a time. "Protein takes the most digestive work, as the foods have to be broken down into amino acids from complex chains," says celebrity nutritionist Kimberly Snyder. This energy spent on digesting protein takes away from what Snyder calls your "Beauty Energy," which she describes as "energy that can be redirected away from digestion to grow thick, healthy hair, clear up dark under-eye circles, repair the collagen in our skin, etc."

SKIN SIN NO. 3: USING TOO MUCH CORTISONE

Cortisone is one of those products in your home's first-aid kit that you most likely use to treat rashes and bug bites. While mild, over-the-counter forms like Cortaid and cortizone-10 can relieve redness, swelling, and flaking, it's easy to forget that cortisone is a type of steroid, and continual long-term use can lead to tachyphylaxis. That's medical speak for cortisone addiction, says Wu. "[When] the skin gets so used to having cortisone around to control any inflammation, it reacts if you suddenly stop using it," she says. "The skin 'rebounds' by becoming angrier and itchier than ever."

Overusing cortisone cream also causes collagen to break down, which leads to thinning of the skin and -- worst-case scenario -- stretch marks. So, how to use this product safely? Wu says to only use it when you really need it, and for a max of two weeks at a time. Also, use the mildest form and apply a very thin layer on areas with thin skin, such as the groin, face, and underarms.

SKIN SIN NO. 4: NOT AIRING OUT YOUR MAKEUP BRUSHES

While we know we should wash our makeup brushes once a week (or at least once a month -- we know how unrealistic it is to give them a good scrub-down every week), Wu says a common mistake is not letting them breathe after washing them.

Need a good reason to take this extra, time-consuming step? "I had a patient who developed a rare skin infection normally seen in aquarium workers and those who work with fish," says Wu. "We traced it back to her makeup brush that she'd been using twice a day but never aired out [after washing]." The lesson: Wash your brushes and don't stash 'em until they're bone dry. And of course, see your doc if you develop a new rash.

SKIN SIN NO. 5: USING RECREATIONAL DRUGS

While there are obvious health reasons to avoid recreational drugs, now there's another (disgusting) consequence that can result if you just say yes: You could find crusty, purplish areas of dead skin on your body that have a good chance of getting infected. Gross.

A recent study in the "Journal of the American Academy of Dermatology" found that patients with this rare disorder, Purpura, all had traces of levamisole in their blood -- a de-worming drug that was found in 70 percent of confiscated cocaine in 2009, according to the U.S. Drug Enforcement Administration.

"We believe these cases of skin reactions and illnesses linked to contaminated cocaine are just the tip of the iceberg in a looming public health problem posed by levamisole," say the study authors. While the de-wormer has been found in cocaine since 2003, drug enforcement officials have found its levels in recreational drugs have risen in recent years due to its efficacy as a diluting agent. As we learned during our elementary school days, the clear message here is don't do drugs. Especially if you don't want ugly, painful purple sores.

SKIN SIN NO. 6: TAKING SUPPLEMENTS WITHOUT A DOC'S APPROVAL

Be wary of miracle supplements that are sold over-the-counter and not recommended by your dermatologist or primary care physician, says Wu, as they can interfere with prescribed medications. For example, calcium supplements can reduce the efficacy of medications like antibiotics or thyroid hormone pills. And vitamin D supplements can make Lipitor (a cholesterol-lowering medicine) less effective.

Wu says, even if you're not on any meds, "mixing supplements can be hazardous to your health." For example, mixing omega-3 fish oil supplements with other supplements like ginger, gingko, or even Advil, can lead to an increased risk of bleeding, which is especially dangerous if you're undergoing surgery or even a teeth cleaning.

SKIN SIN NO. 7: DRINKING YOUR WATER INSTEAD OF EATING IT

You've heard the eight glasses a day rule a trillion times, we know. But it turns out your body doesn't retain a lot of that water, since it goes right through you during your frequent bathroom breaks. The secret to retaining water is by eating it, says Dr. Howard Murad, M.D., founder of Murad, Inc. and author of "The Water Secret."

Murad suggests noshing on foods that have large quantities of H2O, such as watermelon (97 percent water) and zucchini (95 percent water). Cells can more easily absorb the water in food since it comes along with other nutrients that the body needs to absorb. As a general rule, start eating more fruits and vegetables, which have higher percentages of water than processed foods and meat.

SKIN SIN NO. 8: GETTING REFILLS OF PRESCRIPTION PILLS WITHOUT SEEING YOUR DOCTOR

Your dermatologist can prescribe medication for various skin ailments like acne and rosacea, and the prescription can be good for several months at a time. However, Wu says it's a good idea to see your derm again before you refill an Rx. "Some medications need to be monitored closely, such as isotretinoin (formerly known as Accutane)," she says. "[Others] can be harmful to your liver, drop your blood pressure, or cause electrolyte imbalances. I usually see my patients at least every couple of months, or even more frequently [if they're on] isotretinoin."