What Causes Dark Underarms? Here’s What We Know

dark underarms, what causes dark underarms

We’ve all had those big nights out that inevitably lead to dark undereye circles the next morning (ugh, aging). And we know how to deal with those pesky shadows—by pulling out our favorite undereye mask and laying right back down in bed for a little #selfcare.

But when it comes to dark underarms, we’re a little more baffled. What causes dark underarms, and is there a way to prevent them? Here’s everything we know about this skin condition (plus, how to treat dark underarms if you’ve already got ‘em).

What causes dark underarms?

First of all, if we’re being formal for a second, the proper term for that discoloration is hyperpigmentation, a.k.a. a totally harmless skin condition that causes parts of your skin to become a little darker than the skin surrounding it. Hyperpigmentation in itself isn’t dangerous at all, and it’s more often seen in people with darker skin, since they have more melanin already.

But back to the dark underarms specifically. The most likely cause of hyperpigmentation under your arms is irritation, either from shaving or using a deodorant that’s harsh on your particular skin type. Shaving, rubbing, and scratching can all irritate your delicate underarm skin, and that reaction can lead to hyperpigmentation. Remember, your skin is incredibly unique to you; for some people, some deodorant’s formulas might cause hyperpigmentation, especially if you happen to be genetically prone to skin darkening already.

In some cases, dark underarms might be a symptom of acanthosis nigricans, a skin disorder that causes skin to darken and thicken in your body’s folds (like your underarms, groin, neck, and other areas). You might consider talking to a dermatologist if you notice the skin in these areas darkening (especially if you notice the texture change to a more velvety feel, too), but if the darkening is limited to your underarms, it’s more likely to be related to irritation.

How can I prevent dark underarms?

Assuming your hyperpigmentation comes from irritation, your first move is to switch up your shaving routine and perhaps your deodorant too (especially if you’ve been meaning to try a safe, non-toxic deodorant anyway).

With shaving, there are several factors that might be leading to dark underarms. If you ever skip the shaving cream, for instance, the irritation might lead to a hyperpigmentation flare-up. Similarly, a dull razor could cause a skin reaction, as could shaving with too much pressure. Start by using a fresh razor, lathering up with a moisturizing shaving cream, and shaving with a lighter touch.

Deodorant-wise, if you’re still using the same chemical-laden deodorant that you bought at the drugstore when you were in high school, you maaaay be overdue for an upgrade. Switch to deodorant powered by natural, active ingredients. Look for a deodorant that uses known irritants (like baking soda) minimally and offsets them with ingredients like glycerin, which is an all-star skin soother.

How can I treat dark underarms?

If the dark shadows are really bugging you, there are a few things you can do to lighten dark underarms. Talk to your dermatologist; she may recommend skin lightening treatments you can do at home or in the derm’s office, like retinoids, alpha hydroxy acids, salicylic acids, hydroquinone lotion, or other topical treatments (bonus: your dermatologist can also ensure that there’s no underlying medical cause to your dark underarms, so you’ll sleep a little easier at night).

On your own, make sure to moisturize the area daily and again, be super gentle with yourself when shaving and applying non-toxic deodorant. Less irritation means less hyperpigmentation, and soon enough, you’ll be ready for that arms-wide, Insta-perfect pose.

Been using the same drugstore deodorant you bought back in high school? Then it's definitely time for an upgrade.


Written by Kristen Geil