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.

The underarm skin is more sensitive, so clipping it with a razor or causing a rub rash happens to the best of us, too. So if you do want to lighten underarm hyperpigmentation, we asked the experts for their best tips and tricks and why it happens in the first place. But remember: Nobody's underarm skin is perfect, contrary to what you may see online.

As we said hyperpigmentation in the area is extremely common. Here are the reasons it might occur:

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.

This is especially true for those with darker skin tones. Skin color can affect hyperpigmentation as a whole—underarms included. "The theory is that POC melanocytes are more sensitive, and therefore any type of injury can cause post-inflammatory hyperpigmentation," board-certified dermatologist Naana Boakye, M.D., MPH, tells mbg.

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.

The same goes for deodorant or antiperspirant. If you just started using a new product under your arms and a rash has followed, it's probably due to an irritating ingredient. This could be fragrances, exfoliants, or just an allergic reaction.

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

"Things like new-onset diabetes and metabolic syndrome (acanthosis nigricans), a type of psoriasis (inverse psoriasis), certain genetic disorders and infections with fungi, bacteria and/or yeasts can also cause underarm hyperpigmentation," board-certified dermatologist Brandith Irwin, M.D., FAAD, tells mbg.

Gently exfoliating the underarms before shaving may help prevent hyperpigmentation by decreasing the risk of injured skin. "This can give you a smoother shave and lower the likelihood of razor bumps or irritation," board-certified dermatologist Joshua Zeichner, M.D., once told mbg.

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.

Waxing is another option but may cause more irritation to the underarm if it's done too often or using too hot wax. In essence, waxing correctly in this delicate area can be more complicated, so if you choose to do so, proceed with caution.

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.

Some razors are specifically designed for sensitive skin—here are 11 top picks if you're ready to make the switch.

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.

Here are natural deodorants free of baking soda if you're on the hunt.

To get rid of hyperpigmentation anywhere on the skin, "Microneedling, chemical peels, and lasers are great options," Boakye says. However, these procedures should be conducted by a trained professional.

As mentioned above, friction is often to blame for underarm irritation. Try to limit tightfitting clothing (at least for the time being). This kind of irritation is especially likely to occur during exercise or anytime you're moving your arms up and down. Check out some of our favorite yoga clothing here, in case you need to find new options that are more comfortable to move in.

"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." 

This method may not provide instant results, but it is one safe path for those with sensitive skin. Opt for a simple niacinamide serum rather than a complex multi-ingredient blend.

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."

Licorice root3 is another ingredient that’s shown to help with pigmentation concerns.

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.

"Seeing a dermatologist is usually a good idea if it's lasted more than a month or two," Irwin reiterates.

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.

Honey, especially of the Manuka variety, has anti-inflammatory6 abilities. Plus it makes for a great base to blend other brightening agents, such as turmeric. For simple honey masks to try, check these out.

With all of the Photoshop in the world, it's easy to assume that everyone has smooth, spot-free underarms. However, hyperpigmentation in this area is extremely common given that the underarms are more prone to sensitivity. If you try one of these DIY remedies for a few months with few to no results, it's best to consult your dermatologist. If it's dark spots on the face you're worried about, read this.