How to get rid of dark underarms

What causes dark underarms?

One common cause is post inflammatory hyperpigmentation, meaning extra pigment left after irritation or inflammation. Skin produces more melanin, the substance that gives skin its color, in response to that trigger. Shaving, hair plucking, friction in skin folds, deodorants and even lightening products can contribute. Underarm skin has a weaker barrier than skin in some other areas, making irritation a particular concern.34

Another possibility is acanthosis nigricans: darker, thicker patches that feel dry and velvety, often in the armpits, neck or groin. Patches usually appear gradually and sometimes itch or have small skin tags. Obesity is the most common cause, but diabetes, hormone conditions and certain medicines can also be involved. Healthy people can develop it too, particularly people with black or brown skin.2

How do you lighten underarms?

1. 1Get new or unexplained patches checked. A doctor can examine the skin and arrange tests if needed.
2. 2Reduce the products you apply. Choose gentle products labeled for sensitive skin or fragrance free, and reduce rubbing from tight clothes.
3. 3Address the trigger before adding a fading treatment. A rash or another skin condition needs treatment first; continuing irritation can keep producing new pigment.
4. 4Discuss a lightening treatment if discoloration remains. There is no standard underarm treatment, so the choice should fit the cause rather than simply the darkest patch.

Use fewer products on your underarms, which is one skincare task that does not require buying more skincare.1

Which lightening treatments are worth considering?

Niacinamide has some direct evidence for underarm pigmentation. In a small trial involving 24 women, 4% niacinamide was applied every night for nine weeks and worked better than placebo. A good to excellent response occurred in 24% of niacinamide cases, compared with 6% for placebo. That makes niacinamide an option to discuss, not a reason to expect complete clearance. There is no single established strength or application schedule for all dark underarms.3

A doctor can consider creams containing niacinamide, retinol, kojic acid or hydroquinone. Urea or ammonium lactate can help with an abnormally thick outer skin layer. Chemical peels and other procedures are additional options. Laser treatment is not a common first choice for dark underarms, although small underarm studies have found improvement with laser and intense pulsed light treatments. These options belong after assessment of the cause, not in place of it.13

Can shaving cause dark underarms?

Yes. Shaving can irritate or injure skin, triggering extra pigment. If shaving repeatedly irritates your underarms, reducing that irritation is part of fading the marks. Plucking can also contribute, so switching hair removal methods is not automatically the solution.3

Can deodorant cause dark underarms?

Yes, if deodorant causes irritation or an allergic rash. Fragrances, dyes and preservatives in deodorants and shaving creams can be triggers. Try a gentler alternative if your current deodorant causes a rash. A 'natural' label does not mean a product is gentler, because an adjective is not a treatment plan. Naturally derived fragrances, dyes and preservatives can still be present.1

How long does fading take?

For general hyperpigmentation, a patch a few shades darker than your usual skin color often fades within six to twelve months after the trigger stops. Deeper pigment can take years. These are general fading times, not a deadline for underarms. Treatment can speed fading, but new marks can develop if irritation continues. With acanthosis nigricans, patches should fade over time once the underlying cause is treated.24

What should you stop or avoid?

Stop a skincare product that burns or stings. Never apply liquid bleach to skin. Some lightening products have contained unlisted mercury or steroids, so choose products carefully with a dermatologist's help. Do not stop prescribed medicine because you suspect it caused discoloration; ask the prescriber about alternatives. If underarm skin is exposed outdoors, protect it with sunscreen, just as you would other uncovered skin.4

When should you see a doctor?

Book an appointment for new dark patches or skin changes you cannot explain. Acanthosis nigricans can signal prediabetes, diabetes or a hormonal condition such as polycystic ovarian syndrome. Medicines including birth control pills, strong corticosteroids and niacin can also cause it. Rapidly developing thick, dark patches need assessment: rarely, acanthosis nigricans is associated with cancer. Persistent itching or inflammation after changing deodorant also needs medical attention.15