Want To Lighten Your Underarms? Dermatologists Say This Is The Safe Way To Do It. (2025)

When it comes to annoying skincare woes like butt acne or keratosis pilaris (those little bumps you sometimes get on the backs of your arms), dark spots and hyperpigmentation rank right up there. And while the idea of flawless, even skin sounds nice, it's completely normal to have certain parts of the body that are darker (or lighter) than others. One area that comes up frequently in the conversation: underarms.

So why is this area prone to discoloration? "Skin that's subject to chronic friction is typically not monochromatic—there's usually a bit of variation there," says Deeptej Singh, MD, a board-certified dermatologist based in New Mexico. "Genetics may also be at play—ethnicities with naturally darker skin may be at greater risk." For that reason, having even-toned skin in the underarm is a completely unrealistic beauty standard.

Meet the experts: Courtney Rubin, MD, is a board-certified dermatologist and co-founder of the skincare brand Fig 1. Deeptej Singh, MD, is a board-certified dermatologist based in New Mexico.

But while there's nothing wrong with having a little hyperpigmentation under the arms, that doesn't mean there aren't some people who want to lighten the area. That's why I chatted with Dr. Singh and another top dermatologist to answer some of your burning questions about how to lighten your underarms and what causes dark pits anyway.

Read on for all the details.

What causes dark underarms?

Genetics and friction aside, there are other reasons why someone may have dark underarms. The most common one, is known as post-inflammatory hyperpigmentation (PIH), a term refers to discoloration that shows up on the skin as a result of an inflammatory response to some form of trauma. Common causes of post-inflammatory hyperpigmentation include plucking and waxing, putting too much pressure on your skin when you shave, eczema flares, fungal infections, yeast infections, and contact dermatitis, says Courtney Rubin, MD, a board-certified dermatologist and co-founder of the skincare brand Fig 1.

Skincare products like deodorants and moisturizers may also be to blame. The underarm area is super sensitive, as is any area of skin that's folded and subject to constant friction, so "anything that's applied there has a higher chance of causing irritation that on, say, the face or the back," Dr. Rubin says. Common irritants found in natural deodorants include botanical extracts, tea tree oil, lavender, and preservatives like isothiazolinone.

Dark underarms can also be the result of acanthosis nigricans (a common skin pigmentation condition that causes darkening in creases on the body), which is caused by insulin resistance. "We have receptors in the skin that can tell us when our pancreas is producing more insulin, and those areas tend to be at the back of the neck and the underarms," explains Dr. Singh. "That may prompt a dermatologist to do a fasting insulin or hemoglobin A1C test for diabetes or prediabetes."

Rarer culprits for dark underarms include malignant acanthosis nigricans, Lichen planopilaris, and Addison's disease.

How to lighten dark underarms

There are many ways you can try to lighten your darker underarms at home, from easy-to-find OTC products to simple lifestyle swaps. They include:

• Skip intense exfoliation. You may be tempted to lighten your underarms with intense physical exfoliation, but that can make things worse. "Intense scrubbing can break down the skin barrier, causing inflammation and, in turn, post-inflammatory hyperpigmentation," explains Dr. Rubin.
• Stop using products with harsh ingredients. Botanical extracts, harsh acids, lemon juice, or other preservatives can cause irritation. That said, you may have to stop using any products containing them to see if the skin heals itself.
• Change your deodorant. The deodorant you're using may contain ingredients that are irritating your skin and causing the change in pigmentation. Try switching to a gentle deodorant "specifically formulated to be non irritating to those with sensitive skin," says Dr. Rubin. "Vanicream makes a great one with only a few ingredients that is less likely to cause irritant dermatitis."
• Reconsider your hair removal methods. If you usually wax your underarms or have a habit of shaving too hard, consider other options like laser hair removal.
• Try using retinol. Rubin says that retinol, in addition to other ingredients like niacinamide and kojic acid, can be used on the underarms since it promotes even skin tone. You can start out with an over-the-counter formula or check in with your doctor about using retinoids instead.

What in-office treatments are recommended for lightening dark underarms?

The kind of in-office treatment that will be recommended depends on the cause. If you have naturally dark underarms, Dr. Singh notes that a light chemical peel can be useful because it turns over the skin cells and releases some of the melanosomes (which, he says can be thought of as buckets of pigment).

You can also do laser hair reduction instead of shaving if the hair is causing itching or irritation. Plus, if you have darker hair, Dr. Singh says this method can be helpful if stubble contributes to the appearance of dark underarms. Your provider might also prescribe bleaching creams for temporary use.

Still, Dr. Rubin calls out that in-office treatments will work for those who have post-inflammatory pigmentation if the underlying cause of darker underarms is addressed. "It's sort of like playing whack-a-mole—you treat it, but then the underlying inflammation is still happening, so it's leaving behind more pigmentation," she says. "In general, we have the most success with either light chemical peels or laser [treatments] that help address pigment and even tone."

Side effects of lightening dark underarms

If you decide to do an in-office treatment, make sure the provider is experienced with the procedure. Working with someone who isn't well-versed in treating dark underarms increases the risk of it being done incorrectly and making the problem worse, says Dr. Rubin.

Lightening and bleaching creams also have side effects to consider before trying them. While these creams will lighten the skin, Dr. Singh warns that, if abused or used incorrectly, they can cause skin thinning, steroid acne, and permanent stretch marks. Additionally, it was found by the FDA in 2022 that there may be traces of mercury and hydroquinone (an active drug ingredient) in some skin-lightening brands. The FDA currently does not allow mercury in cosmetic products unless it's under specific conditions. Hydroquinone is also not considered safe by the FDA.

"Those creams must be prescribed by a dermatologist or another physician," says Dr. Rubin. "It's not safe if someone is pregnant, breastfeeding, or trying to conceive and usually has to be used only for a limited time period because if it's used for months without any breaks in the skin, it can actually cause worsening of the pigmentation."

Bottom line: Dark skin under the arms is totally normal and totally nature, but if you choose to lighten the area, there are plenty of options at your disposal. Just do your research—the wrong moves can do more harm than good.