Causes Of Underarm Hyperpigmentation + 9 Ways To Lighten Underarms, From Derms

Before we dive into the ins and outs of underarm hyperpigmentation, let's get one thing clear: Photoshopped ads may have you believe that everyone has perfectly smooth, even-toned underarms. The truth? Some people naturally have darker underarms as is—and that's perfectly normal.

Shaving with a dull razor is known to cause a plethora of problems, mainly because you're more likely to cut the skin and create a rash. This is because a dull razor will pull at the hairs and the skin.

Irritation under the arms can be caused by a few different factors. First up, we have tight clothing. If your shirt is rubbing back and forth on your underarm, you're more likely to experience a rash.

If your underarm hyperpigmentation just won't lighten up, it could be caused by an underlying disease or skin condition.

If you've tried time and time again to mitigate shaving irritation, you may consider opting for laser hair removal instead. "Laser hair removal is the best way in the long run but may cause some short-term irritation," Irwin explains.

If you're using a single- or double-blade razor, that may be the cause of your underarm irritation—especially if it's on the older side. In order to optimize your shaving routine, "use a hypoallergenic shave cream (not soap or body wash)," Irwin recommends. Further, never let your razor go dull.

Again, your irritation may be caused by a topical deodorant or antiperspirant—especially if it's new. "Ideally avoiding products with baking soda (if you are sensitive), fragrance, and other possible irritants," Boakye recommends. "This is very individualized," she continues.

"Niacinamide is anti-inflammatory and able to inhibit the transfer of melanosomes to keratinocytes1," Boakye explains. "Therefore, it is able to brighten the skin at the right concentration over time." 

Since it’s a very sensitive area, you’ll want to avoid many of the common brightening ingredients (AHAs, vitamin C, physical exfoliants) as these will likely only cause more damage. However, there are many other brightening ingredients that may help the area without the irritation baggage.

Kojic acid (which is a byproduct from fermenting mushrooms) is most known for its skin-lightening properties, as studies echo its ability to brighten skin and fade dark spots.2

Alpha arbutin also helps correct hyperpigmentation and dark spots, notes board-certified dermatologist Keira Barr, M.D.: "Arbutin is a naturally occurring compound in the leaves of a variety of different plants, including pear trees and the bearberry plant, that prevents the formation of melanin."

As stated, underarm hyperpigmentation can be a sign of a plethora of other skin conditions and underlying diseases. If this hyperpigmentation is bothering you, it's best to see your derm.

While we normally support at-home treatments when available, the underarms are very sensitive and prone to irritation (as we’ve noted throughout the article). For this reason, you should really proceed with caution before doing any DIY mask, scrub, or tonic to lighten underarm hyperpigmentation. 

In fact, most of the at-home underarm treatments you see on the web are likely too harsh for the skin (looking at you, lemon juice and baking soda). 

If you’d like to experiment with at-home remedies, please stick to soothing ingredients such as aloe or honey. 

Not only does aloe have anti-inflammatory properties4, it can help with pigment production too. Aloesin, a natural compound in the aloe plant, has brightening capabilities that can help speed up this fading process. In one study, when aloe was applied to skin four times per day for two weeks, aloesin was shown to effectively fade post-acne hyperpigmentation5. Another report showed that topical application of aloesin can directly inhibit hyperpigmented skin from producing more melanin.