Underarm whitening treatments: what works?

What is making your underarms darker?

A common cause is postinflammatory hyperpigmentation, meaning extra pigment left after inflammation or injury. Shaving, plucking, friction in skin folds and deodorants can trigger it. Underarm skin has a weaker barrier than skin in some other areas, and whitening products can themselves contribute to irritation and darkening. There is no standard treatment for dark underarms, despite how confidently a jar can name itself.34

Not every dark patch is the same problem. Genetics, a rash and other skin conditions can also cause underarm discoloration. Acanthosis nigricans is a condition that produces darker, thicker, velvety skin, often in the armpits, neck or groin. Lightening creams come after identifying the cause, which gives the word "whitening" less authority than the packaging intended.15

When should you get dark underarms checked?

Book an appointment for new dark patches or changes you cannot explain. Acanthosis nigricans can be associated with obesity, type 2 diabetes, hormone conditions and certain medicines. It also occurs in otherwise healthy people. A clinician can usually recognize it by examining the skin and can arrange tests to investigate the cause.2

Dark, velvety skin does not automatically mean diabetes. In darker skin tones, acanthosis nigricans can occur without insulin resistance, where the body responds poorly to insulin. Your medical history, medicines and other symptoms help determine what needs checking.6

Arrange a medical assessment if thick, dark patches develop rapidly or become widespread. Rarely, rapidly developing acanthosis nigricans is associated with cancer. Treating an underlying medical problem takes priority over changing the skin's appearance; the patches often improve when their cause is treated.5

How to start an underarm lightening routine

1. 1Identify the trigger first. Look at whether darkening followed shaving, plucking, rubbing from tight clothes or a product that caused irritation.
2. 2Reduce the number of products applied to the area. Choose products intended for sensitive skin and look for fragrance free options. Consider changing deodorant if it causes a rash or irritation.
3. 3Address ongoing inflammation before adding a lightening treatment. Repeated injury can keep pigmentation going, even while you are trying to fade it.
4. 4Choose a treatment suited to the cause. A dermatologist can help select a cream or procedure if product changes are not enough.

Which treatments are worth considering?

How do you use niacinamide for dark underarms?

A 4% niacinamide cream applied at night for nine weeks improved underarm pigmentation in a small trial of 24 women. A good to excellent response occurred in 24% of niacinamide treated underarms, compared with 6% receiving the cream without niacinamide. These results concern healthy women with medium to darker skin tones, not people with acanthosis nigricans or an underlying systemic condition.34

The tested routine was nightly treatment, with an antiperspirant allowed in the morning. The formulation was a moisturizing cream containing 4% niacinamide, so a stronger facial serum is not the same treatment. Pregnancy and breastfeeding were excluded from the trial; have a clinician choose a suitable treatment in those situations rather than copying this regimen.3

Desonide 0.05% produced more lightening than niacinamide in the same trial, with a good to excellent response in 30% of treated underarms. Because desonide is a steroid medicine, discuss it with a clinician rather than using it as an everyday whitening product.3

Are peels or lasers better than creams?

Small underarm studies have reported improvement with Q switched Nd:YAG lasers and intense pulsed light, or IPL. One comparison found IPL better than an alpha hydroxy acid treatment for lightening and texture. Both laser and IPL treatments had reported side effects, with pain reported more often with the laser. There is no single established best treatment.4

Chemical peels, dermabrasion and microdermabrasion are other professional options. Laser treatment is an option rather than the usual starting point, even if a machine makes the appointment sound more decisive. For acanthosis nigricans, managing the underlying condition remains the main treatment; a dermatologist can consider creams or procedures to improve appearance afterward.16

How long does underarm lightening take?

Think in weeks to months, not days. The niacinamide and desonide treatments were assessed over nine weeks. For postinflammatory pigmentation generally, a patch a few shades darker than your usual skin tone often fades within six to twelve months after the trigger stops. Deeper pigment can take years. Treatment can speed fading, but continued irritation can produce new patches.37

What should you avoid?

• Stop a product that burns or stings. Seek medical advice if inflammation or itching persists after changing the suspected deodorant.
• Do not overexfoliate. Lemon and other acidic home treatments can irritate skin, so discuss them with a doctor before trying them.
• Never apply liquid bleach to skin. Some imported lightening products have contained mercury or steroids missing from their labels; choose a product made in the United States or recommended by a dermatologist.
• Do not stop prescribed medicine because you suspect it caused pigmentation. Ask the prescriber about the side effect and possible alternatives.
• Protect underarm skin if clothing leaves it exposed outdoors. General pigmentation care includes tinted sunscreen with iron oxide, SPF 30 or higher, broad spectrum protection and water resistance.