Body Care

Ask a Derm: What’s Causing My Dark Underarms?

how to lighten dark underarms

Dark underarms may seem like a niche concern, but that’s only if you don’t have them. For others, particularly people of color, discoloration of the armpits can be frustrating, especially in the summer and when taking photos. As it is, armpits aren’t exactly anyone’s best feature. But, usually, dark underarms are perfectly normal, and that discoloration is just a side effect of the area being, well, the armpit.

However, while the expectation that our skin should be even in tone everywhere is flat-out unrealistic, visible discoloration or a shadow can make some people feel self-conscious. And, if it does impact bigger things in your life, like whether you wear a sleeveless dress and how you pose for photos, then there’s no harm in addressing it.

First, know that dark armpits are usually completely normal. “It’s [typically] not a problem,” says Alicia Barba, MD, a board-certified dermatologist in Miami, Florida. “It [can be a] genetic predisposition to have a bit more pigment in areas that are constantly under friction, like under the arms — friction from skin against skin, skin against clothes, and our beauty practices, like shaving, being too harsh with the razor, over-exfoliation, [and] waxing, [can all cause darkened skin].”

Friction in a specific area from constant rubbing can give rise to chronic inflammation. “It’s more of a subtle, very low-grade inflammation over long periods of time,” says Dr. Barba. “You may not even perceive it.” And that can set off a domino effect in skin — primarily in the melanocytes, which are the cells that churn out the pigment in your skin. The effect is similar to the brown marks some people experience after, say, a breakout, but more gradual and subtle.

On top of the everyday friction caused by skin against skin or skin against clothes, those aforementioned grooming habits can only worsen matters. ”Could you maybe be using the wrong product? Were you burned by a laser? Are you using very hot wax?” Dr. Barba asks her patients. Just as common are mistakes made when you’re shaving your underarms, whether you’re doing a dry shave in a hurry, working with a dull blade, or skipping a shaving gel or cream altogether. “At the very least, lather up with some soap, because you’re exfoliating,” she says. “And we’re constantly doing that to [underarm] skin, which is always exfoliated from the friction of skin against skin, so it’s like a double whammy.”

The resulting hyperpigmentation can be vexing to treat. Dr. Barba gives this visual to her patients: Imagine the melanocyte as an octopus. Each tentacle is busy tossing bundles of melanin up to the epidermis, where it appears as dark pigment. While some treatments, such as exfoliation and retinoids, work to improve the appearance of the skin, they don’t stop the melanocyte from spreading pigment. Rather, “the majority [of treatments] just slough off the top layer of epidermal cells that have already picked up the pigment,” she explains. To get to the source, look for “actives that treat it at all different levels — minimizing the production, blocking the transfer, and sloughing off the epidermal cells that have the pigment.”

Editor's Note

 As always, talk to your doctor before starting any new treatment. Retinol shouldn't be used by women who are pregnant, considering getting pregnant, or nursing. Please consult with your doctor before use.

Those melanin-inhibiting ingredients include hydroquinone, alpha-arbutin, and niacinamide (a.k.a. vitamin B3). But, you have to balance the strength of the ingredients with the sensitive skin of the underarms, which makes niacinamide an especially good option — it’s able to walk the line between effective and gentle. That’s why it’s one of the main ingredients in Dove’s® Even ToneTM Antiperspirant ($6). “There are clinical studies that show an evening out of the skin tone after [four] weeks of daily [niacinamide] use,” says Dr. Barba.

Editor's Note

Hydroquinone has not been FDA-approved. Talk to your doctor before starting any treatment with it.

In Even Tone Antiperspirant, niacinamide is paired with moisturizing ingredients and 12-HSA, which, Dr. Barba explains, “is a wonderful emollient that’s protecting the stratum corneum, so the barrier is maintained.” In fortifying the protective barrier, it gives skin a chance to restore itself, from the basal cells, which are at the bottom of the epidermis, to the corneocytes at the skin's surface.

On top of that, it’s essential to minimize damage inflicted on skin when you’re grooming. First up: shave with a sharp, clean razor designed for sensitive skin, such as Gillette Venus® Extra Smooth Sensitive Razor ($13). Also, always lather up with a shave cream or soap. Eos® Shave Cream ($4) delivers nourishing oils while lending an extra layer of protection between your razor and your skin.

What are absolutely not recommended are the usual heavyweights for discoloration, like lasers and peels. “I’m very cautious in using lasers in skin of color, for many reasons,” says Dr. Barba. Lasers deliver a controlled burn to skin, while peels remove its protective superficial layers in order to get rid of pigment. During the healing process, though, those with darker skin tones are at a higher risk of changes in pigmentation — so any efforts like that could backfire. When you’re dealing with dark underarms, slow and steady — and gentle — wins the race.

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