7 Things Every Woman Should Know About Her Skin

You probably don't realize it, but your skin is constantly reinventing itself: The outer layer regenerates every month. Your body's biggest organ needs to stay in tip-top shape because it has important jobs to do—like shielding you from pathogens, the elements, and everyday bumps and falls. You can help by giving your skin the TLC it deserves. That means eating the right nutrients, slathering on sunscreen, and checking for suspicious spots, says Jessica Wu, MD, professor of dermatology at the University of Southern California's Keck School of Medicine. Bonus: Those same healthy habits will keep your skin soft, smooth and gorgeous, too.

In order to understand how to keep your skin healthy, it helps to know these important terms:

The epidermis makes new skin and the pigment melanin. It also contains Langerhans cells, which help regulate your immune system.

The dermis holds the subepidermal structures of the skin in place.

Subcutaneous fat cushions and protects your body and helps you stay warm.

Sebaceous glands produce an oily substance to keep your skin smooth and soft.

Blood vessels remove waste (like CO2) and ferry nutrients through the layers of the skin.

Hair follicles attach to tiny muscles that cause your hair to stand up (giving you goose bumps) and trap heat when you're cold.

Sweat glands secrete perspiration to moisten the surface of the skin and cool you down.

Nerves send signals to your brain, so you know how something feels and react to it (e.g., you pull your hand back from a hot pot).

Got a lot of deep creases? You might be at a higher risk of developing low bone density postmenopause, according to a Yale School of Medicine study. That makes sense, says Debra Jaliman, MD, professor of dermatology at the Icahn School of Medicine at Mount Sinai in New York City, because skin and bone are made from the same type of collagen. Another study, from the Netherlands, found that women with saggier skin had higher blood pressure. "Wrinkles can signal that your body is not making enough of the protein elastin, which helps keep both your skin and blood vessels supple," notes Dr. Jaliman. Wrinkles could also be a hint that you need more shut-eye: Women who received five or fewer hours a night had more fine lines than those who logged a full night's sleep, according to a 2013 study. When you skimp on rest, your body has less time to do its nightly repair work on collagen and elastin, explains Dr. Jaliman.

It's important to alert your derm to any new growth. But it's especially vital if the mole exhibits one or more of the ABCDE signs of melanoma: asymmetry, border irregularity, color variations, a diameter that's larger than a pencil eraser's, and an evolving size, color or shape. You should also have your derm examine anything that looks like a pimple or ingrown hair and doesn't go away within three weeks. "It could be either basal or squamous cell carcinoma, the two nonmelanoma forms of skin cancer," says dermatologist Shawn Allen, MD, spokesperson for the Skin Cancer Foundation. These are much less likely to be deadly but still require removal; and the longer you wait, the larger they grow.

If you notice a suspicious spot, you may be tempted to use a skin cancer app that lets you submit a picture for either automated analysis or a dermatologist's opinion. "These are unreliable," cautions Dr. Allen. "It's hard enough to make the call as to whether something needs to be biopsied when the person is standing right in front of you." The better move is to always schedule a face-to-face appointment.

If you're unhappy with freckles, sunspots, or melasma (patches of gray-brown skin), these treatments can erase 'em.

Tri-luma: This Rx cream packs a triple punch: the skin bleacher hydroquinone, a skin-sloughing retinoid and a steroid to reduce irritation. Since high doses of hydroquinone have been linked to cancer in rats, many doctors recommend that you limit use. Cost: around $150 for a four-month supply.

Glycolic acid peels: These medical-strength peels contain at least 30 percent glycolic acid, and some dermatologists will mix in hydroquinone for extra potency. Most women require three to five peels before they see results. Cost: $200 to $250 per peel.

Lasers: They are very effective at zapping freckles and sunspots, says Heather D. Rogers, MD, professor of dermatology at the University of Washington School of Medicine in Seattle. Patients generally need three or more treatments. Cost: about $500 per session.

"As you enter perimenopause"—which can start as early as your 30s—"your estrogen levels drop, while male sex hormones, like testosterone, remain nearly constant," says Dr. Wu. That imbalance may send your oil glands into overdrive, causing you to break out like a teen. Look for OTC products with retinol, which fights both wrinkles (by increasing cell turnover) and pimples (by unblocking pores). Or ask your derm about a prescription retinoid, like Renova, which may be a good choice for aging skin. But if you're experiencing big, pustulelike cysts, you likely need something stronger: "I sometimes put patients on the blood pressure medication spironolactone, which restores hormonal balance," says Dr. Jaliman.

While some foods can help prevent UV damage, others can cause problems (from acne to aging). Here, three smart trades to try for healthier skin.

Instead of blended coffee drinks, drink plain iced coffee. Dairy can worsen acne; sugar helps break down collagen, says Dr. Wu, author of Feed Your Face. On the other hand, having four or more cups of coffee a day was associated with a 20 percent lower risk of melanoma in a 2015 Yale study.

Instead of grilled steak, eat salmon. Red meat that's cooked at high temps is more likely to form advanced glycation end products, which can play a role in aging. Salmon is rich in anti-inflammatory omega-3 fatty acids. A study published in 2009 suggests that a serving of oily fish every five days may protect against pre-cancerous changes.​

Instead of lots of citrus fruits, eat watermelon. Citrus contains substances called psoralens, which make your skin more sensitive to UV rays, and have been linked to an increased risk of melanoma. Like citrus fruits, watermelon are chock-full of skin-rejuvenating vitamin C—but they don't have any psoralens.

What you need to know about embarrassing perspiration issues.

First of all, why do we perspire? It's your body's way of regulating your temperature, says Dr. Jaliman. There are two types of sweat glands: eccrine, which are found all over your body, and apocrine, which are located in areas with a lot of hair follicles, like your armpits and groin. Your eccrine glands produce mostly odorless water and salt; your apocrine glands, however, churn out a milky fluid that combines with skin bacteria to create BO.

How can I prevent rashes and breakouts caused by sweat? Start by wearing looser workout gear, since rashes can be a result of friction from damp clothing, says Dr. Wu. And shower as soon as you can after each workout (or wipe down your face, chest and back with salicylic or glycolic acid pads). If the problem persists, try applying antiperspirant on your inner thighs and under your breasts to stave off rashes and chafing.

My palms drip when I'm nervous. What can I do? About 3 percent of people in the United States have hyperhidrosis, which means they sweat too much, often from one or two areas of the body (usually the underarms, palms, feet or head), according to Malcolm Brock, MD, director of the Johns Hopkins Center for Sweating Disorders. If you're diagnosed with the condition, there are a number of treatment options, including prescription deodorants and Botox.