Dark Armpit Causes and Treatments, According to Dermatologists

Dermatologists share four common causes of darkened armpits, and how to address the issue if it's causing you concern.

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Finding dark patches of skin on your armpits is super common and often not all that noticeable. But many people who experience darkness in their underarm region (🙋🏻‍♀️) will tell you that it can still be a source of insecurity, especially as the weather gets warmer and tops become smaller.

The good news is that dark armpits are usually an aesthetic concern that's harmless, according to experts. And even then, if the shadows in your underarm area are stopping you from wearing tank tops, there are steps you can take to combat the common issue.

Why Are My Armpits Dark?

Before you jump in to trying treatments, it's key that you understand the common causes of dark armpits.

Hyperpigmentation

The most common cause of dark armpits is hyperpigmentation, which is a typically harmless condition in which skin produces extra melanin (pigment), creating the appearance of brown, gray, black, or pink spots on the body, explains Tiffany Clay, M.D., a board-certified dermatologist. (Related: 7 Causes of Dark Circles Under Eyes, According to Dermatologists)

Generally speaking, many factors can lead to hyperpigmentation. The risk factors that can cause darkening in the underarms are genetics, hormonal changes such as puberty or pregnancy, and injury to the skin, according to Dr. Clay.

One of the most common causes of hyperpigmentation in the underarm area is inflammation due to an injury from shaving, which is infamous for causing irritation, cuts, and pesky ingrown hairs. (This tends to result in smaller dark spots rather than darkening your entire armpit.) "Any injury or trauma to the skin from a rash or ingrown hair is going to produce more melanin leading to hyperpigmentation," explains Dr. Clay.

Acanthosis Nigricans

Another potential cause of dark spots under your arms is a skin condition called acanthosis nigricans. "Acanthosis nigricans is the thickening and darkening of the skin that occurs most commonly around the folds of the skin on the neck," explains Dr. Clay. "It occurs more often in obese and diabetic [people] because they are likely to be in a state of insulin resistance, which increases skin thickness." The excess insulin causes the skin to produce cells at a rapid rate, which includes the production of pigmented cells, explains Dr. Clay.

Other common areas that will show symptoms of acanthosis nigricans are the groin and — you guessed it — armpits, according to the Mayo Clinic. Those with acanthosis nigricans may also notice their skin is itchy, has an odor, or is prone to developing skin tags, which are small, benign skin growths.

Infections

Little did you know yeast infections aren't limited to down there. The infections can occur in other areas of the body and can cause hyperpigmentation. "Underlying yeast infections may cause darkening of the skin, especially where skin touches the skin, for example, the groin and underarms," says Rina Allawh, M.D., a board-certified dermatologist at Schweiger Dermatology Group in King of Prussia, Pennsylvania. "This is typically caused by a normal skin yeast that overgrows during the hot and humid climates."

Typically the infections will begin as pink, scaly, itchy patches that look like rash. The overgrowth of yeast interferes with your skin's pigment production, results in discoloration, according to the Mayo Clinic. To treat a yeast infection, it's best to consult with a doctor to ensure you're treating the actual fungal infection instead of the hyperpigmentation, which is a symptom, says Dr. Allawh.

Allergic Reactions

Some ingredients found in deodorants or body cleansers may cause a skin reaction, such as burning, rashes, or itchiness that results in darkening of the skin if you're allergic to the ingredients, explains Dr. Allawh. "Common culprits are fragrance and dyes in clothing that may cause a skin reaction," she says. Allergic reactions, such as rashes, can cause trauma or injury to the skin when you scratch, resulting in inflammation and hyperpigmentation. "Skin allergy testing called patch testing may be helpful to really narrow down the potential causes and avoiding those skin allergens is helpful to prevent worsening of the skin irritation and hyperpigmentation."

How to Get Rid of Dark Armpits

If you have dark armpits, it's best to visit a dermatologist who can help you figure out the underlying cause and an appropriate treatment.

As for how to lighten dark armpits that aren't caused by a more serious issue, over-the-counter skin-care products formulated with retinol or adapalene can be helpful, since they fight discoloration by promoting cell turnover, says Dr. Allawh. Fresh cells can replace the older, pigmented cells. (Related: Kojic Acid Is the Hyperpigmentation-Fighting Ingredient Your Skin-Care Routine's Missing)

You can shop for deodorants that are formulated to promote a more even skin tone, such as the Dove Even Tone Antiperspirant Deodorant Restoring Powder, which is made with dark spot-fighting niacinamide. You can also reach for brightening leave-on products, such as Bushbalm Bermuda Dark Spot Oil, which incorporates lemon peel oil to exfoliate dead skin cells. (Related: Azelaic Acid Is the Hero Ingredient You Should Be Using for Acne and Dark Spots)

If you suspect the cause of your underarm darkness is due to injuries from shaving, consider switching to laser hair removal, which "may be helpful to prevent further ingrown hairs and to prevent further darkening of the skin," says Dr. Allawh. Other in-office treatments can fight existing hyperpigmentation. "Some laser treatments may be able to help lighten the darkened skin and allow you to feel more confident," says Dr. Allawh.

Often, dark armpits are nothing to worry about. Once you've ruled out a larger issue, you can address them with a few adjustments to your routine, if you feel so inclined.

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