Taking Care of Your Skin

— Mary, Minnesota

Darkening of the armpit skin can be caused by a number of conditions. Since others in your family have the same problem, you may have acanthosis nigricans, which can be hereditary and is characterized by dark patches of thick, velvety skin on the underarms, thighs, and/or sides of the neck. It's often associated with insulin resistance or other hormonal imbalances. It's thought that elevated insulin levels can overstimulate skin cells, leading to thickening and darkening of the skin in certain areas. I strongly recommend a visit to your regular doctor to see whether you are at risk of diabetes. If this is the case, the dark patches may eventually fade when the underlying hormonal disorder is treated. You can also try topical creams containing lactic acid or glycolic acid to help exfoliate the dark patches, but the underarms can be very sensitive, so be sure to use these products sparingly and stop if you experience redness or irritation. You may also want to find a dermatologist who has experience in prescribing fading creams. Just be patient, because they can take several months to work.

Shaving can also make the armpits look dark. Underarm hair tends to be darker and coarser than hair elsewhere on your body. Stubble can be visible under the surface of the skin, especially if there are ingrown hairs. If this is the case, waxing can help because it removes the hairs from the root, leaving no stubble.

Finally, the bacterial infection erythrasma can produce dark brown patches in the underarms. It's caused by Corynebacterium minutissimum, which is normally found on the skin of the armpits and groin. When your body chemistry changes (when you perspire, for example), the bacteria overgrow, producing a localized infection. Your dermatologist can do a simple test by shining a Wood's lamp (an ultraviolet light) on the affected area; if you have the infection, the patches will glow a magenta color. This infection is usually treated with topical and oral antibiotics.

Regardless of the cause, there are ways to minimize the discoloration, so don't give up!

Q2. Are those home chemical peel treatments safe to use, and do they work as well as the ones done at a spa or the dermatologist?

In the right situation, home peel treatments can be safe and effective. However, peels that are done at home or at a spa are not as potent as the medical- strength peels that can be done by a dermatologist or plastic surgeon.

Most home peels consist of one or more alpha-hydroxy acids such as glycolic (up to 30 percent) or lactic acid. These acids work by dissolving and exfoliating the superficial layers of dead skin to reveal the new, fresh skin underneath. Some home peels contain salicylic acid, which is a beta-hydroxy acid. Salicylic acid is lipophilic, which means it’s attracted to the oil glands and helps to unclog pores. Other home peels contain enzymes, which are designed to exfoliate but are not as effective as the hydroxy acids. In general, at-home and spa peels can help improve mild acne and early sun damage. They can also temporarily improve skin texture and overall skin tone.

Medical-strength peels are stronger and penetrate more deeply into the skin, so they are more effective at treating pigmentation problems (like melasma), scarring, fine wrinkles, and deeper sun damage. However, they also require a longer recovery time. Physician-strength peels include glycolic acid (30 to 70 percent), trichloroacetic acid (TCA), or phenol solutions. These stronger solutions often require pre- and post-peel topical treatments to help ensure an even peel and a quicker recovery.

I would recommend a visit to your dermatologist, who can examine your skin and advise you on which strength of peel would be best for you. Even if you prefer to do home peels or see a facialist rather than a doctor, it’s important to discuss this with your dermatologist to make sure it’s safe to do a peel on your skin.

Here are some other situations in which you need to check with your dermatologist before doing a home peel:

If you have an underlying skin condition (such as eczema or psoriasis), it is especially important to check with your doctor because a peel could make your skin more sensitive.

If you’ve recently used a prescription-strength retinoid product (such as Retin A), this could make you more sensitive to the peel solution.

If you have a tan or have been in the sun recently, it may be best to wait for the tan to fade before doing a peel. Those with darker or more olive skin tones may develop blotchy discoloration after a peel.

If you have had cold sores in the past, a peel (even a home peel) could re- activate the herpes virus and trigger an outbreak that could spread to the entire face. If you have had cold sores, you should discuss this with you doctor before doing a home peel, since you may need to take a medication that helps suppress the virus and prevents the outbreak from spreading.

Lastly, I strongly urge you to avoid buying medical-strength chemical peel solutions over the Internet. I have seen several patients in my office who have been burned and even scarred from using these solutions. Be sure to discuss any type of peel with your dermatologist before doing it yourself, and if possible, bring the product with you to your visit so your doctor can check the ingredient list.

Q3. I have been using Dovonex (calcipotriene) for my genital psoriasis for 13 years. I also use lotions on a regular basis, particularly when I'm in a relationship, as the medicine is a bit inconvenient. My psoriasis is by no means as horrifying as it was when I was first diagnosed with it at 15, but it still peels lightly every morning and by the end of the day, is always slightly pink, and is of course a noticeable ring when I'm stressed. I've managed to hide it fairly well over the years, but in doing a bit of reading, it sounds like it should clear up for most people. Should it actually be nonexistent after all this time? Is there an alternative treatment I should consider? My new dermatologist is convinced I have an allergy (and doesn't believe the doctor's diagnosis from when I was a teen), but an allergy for 13 years seems kind of unbelievable – never mind the peeling. I would love your insight, thanks!

This is a tough scenario, when a patient is caught between the opinions of two physicians. Shows you how cut and dried “practicing” medicine is, right?

Psoriasis can come and go without good reason and could easily persist for 13 years or longer without clearing up. I tell my patients that we try to focus on control, not cure.

Dovonex is very safe to use long-term, but if you are looking to change things up, you could add a low-strength cortisone or a medication like Protopic 0.1 percent (tacrolimus). With appropriate follow-up, all of these would be safe options.

If you’re troubled by the possibility of an allergy, it might help you clarify your diagnosis by having patch tests for possible allergens in your environment. As a simple precaution, however, I would get rid of all fabric softeners and any products such as soaps, lotions and detergents that smell or look pretty (they come in bright colors like pink, green, or blue, for example) because these contain ingredients that can irritate the skin.

Q4. Is it any safer to get a tan in a tanning bed vs. tanning outside?

— Carly, Minnesota

Although many tanning salons advertise that their tanning beds will give you a “safe” tan, getting a salon tan can actually be deadlier than tanning outside. When you sit outside in the sun, you’re getting a combination of ultraviolet A and B (UVA and UVB rays). UVB (burning) rays cause sunburns, while UVA (aging) rays stimulate your skin’s pigment cells to produce a tan. UVA rays have also been linked to melanoma, the most deadly type of skin cancer.

When you go to the beach and after you’ve gotten a certain amount of sun exposure, your skin will start to burn, and you’ll either cover up or go indoors. The problem with so-called “safe” tanning beds is that they typically bombard your skin with UVA rays alone. While you usually won’t get sunburn in these beds, your skin is being invisibly damaged because these rays penetrate even deeper in the skin than the UVB rays. You may not even be aware of the extent of the damage until years later, when you develop signs of UVA damage. These can include brown spots, rough blotchy skin, precancers, and skin cancers. I’m currently treating several adult women who regularly visited tanning beds when they were in high school and college. Some of them have developed precancerous moles that I’ve surgically excised. Remember: The only safe tanning salon is one that sprays on your tan.

Q5. I have tried all sorts of medications to manage my severe psoriasis, most of them steroid creams. I find them inconvenient and messy. The only thing that seems to have worked is a tanning bed/UVB therapy. Do you have any suggestions other than the light therapy? I'm worried about too much UV exposure to my skin.

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