Underarm Hyperpigmentation and the Everyday Habits Behind It

Straight answer

Underarm hyperpigmentation is most often the skin’s response to repeated low-grade irritation. Shaving, plucking, skin-on-skin friction and reactions to fragranced deodorants each cause small bouts of inflammation, and inflamed skin makes extra pigment. Finding and removing your personal trigger does more than any fade cream, and the AAD says mild discoloration usually fades within 6 to 12 months once the cause is gone.

A 2025 systematic review of underarm pigmentation lists the usual triggers in one line: body folds, friction, hair plucking, shaving and deodorants (Vahabi et al., 2025). Most people have more than one. This guide takes them one at a time, explains how each one leads to darker skin, and gives the specific change that helps. For a broader overview, including medical causes such as acanthosis nigricans, see our main guide to dark underarms.

How irritation turns into underarm hyperpigmentation

When skin is inflamed, pigment cells ramp up melanin production, and some of that pigment lingers after the inflammation settles. Doctors call it post-inflammatory hyperpigmentation (PIH). Biopsies from a trial of women with darkened underarms showed an inflammatory infiltrate and damage at the junction between the outer and deeper skin layers, both of which improved with treatment (Castanedo-Cazares et al., 2013). In other words, this is an inflammation problem that shows up as a color problem.

PIH is more common and more visible on medium and deep skin tones, and the 2025 review notes it is more prevalent in women, especially women with darker skin (Vahabi et al.). That’s why the same razor that leaves one person’s underarms unchanged leaves another’s noticeably darker.

Shaving and other hair removal

Why it darkens skin

The AAD notes that frequent shaving can irritate the skin and lead to ingrown hairs (AAD). In the underarm, where skin is thin and folded and hair often grows in several directions, every pass of a dull or dry blade adds friction. Plucking appears on the review’s trigger list too (Vahabi et al.). Waxing carries risks of burns and redness, according to the AAD.

What to change

• Shave on wet, softened skin, ideally at the end of a shower, with a shaving cream or gel (AAD).
• Shave in the direction the hair grows, rinse after each swipe, and change blades after 5 to 7 shaves (AAD).
• Map your growth pattern: underarm hair often grows in two or three directions, so shorter, gentler strokes work better than one long pull.
• Stop plucking stray hairs in the area.
• Consider laser hair removal if shaving irritation keeps coming back. Most people need 2 to 6 treatments, and the AAD stresses that the person treating darker skin must be highly experienced, because laser hair removal has to be done very carefully on those skin tones (AAD). Burns, blisters and dark spots are possible risks (AAD).

Deodorant and antiperspirant

Why it can darken skin

Deodorants are on the review’s list of irritants linked to underarm pigmentation (Vahabi et al.). The more established problem is allergy. In a Danish study of 17,716 people patch tested for allergies, deodorants were the leading cosmetic cause of fragrance allergy, especially in men (Heisterberg et al., 2011). A dermatology review of 107 deodorant and antiperspirant products found fragrance in 90% of them and propylene glycol in 47%, and noted that the underarm may be predisposed to allergic reactions because of prolonged occlusion (Zirwas and Moennich, 2008).

An allergic or irritant reaction shows up as itching, redness, burning or a rash where you apply the product. On deeper skin tones, redness can be subtle, and the first sign you notice may be darker, slightly rough skin.

What to change

• Switch to a fragrance-free product. The deodorant-allergy review recommends trying fragrance-free products as a first step, before formal testing (Zirwas and Moennich).
• Note that “unscented” can still contain masking fragrance; look for “fragrance-free” and check the ingredient list.
• Apply to dry, intact skin, and skip it on any day you’ve nicked yourself shaving.
• If a rash keeps coming back, ask a dermatologist about patch testing. Standard testing can miss some fragrance allergies, so bringing your own products can help (Zirwas and Moennich).

A note on marketing: deodorants sold as “for dark underarms” contain the same kinds of ingredients you’d find elsewhere. The most useful feature of any deodorant for discolored skin is that it doesn’t irritate you.

Friction, sweat and skin folds

Why it darkens skin

Skin rubbing on skin, in a warm, damp space, is a recipe for inflammation. DermNet describes intertrigo, a rash in skin folds including the underarms, as more common in people who are overweight, have diabetes or sweat heavily, and notes it can become infected with yeast or bacteria (DermNet). Even without a full-blown rash, daily friction from workouts and tight sleeves adds up.

What to change

• Dry the underarms thoroughly after showering and sweating. DermNet even suggests a hairdryer on a cool setting for skin folds (DermNet).
• Wear loose, breathable clothing, and choose workout tops that don’t saw at the armpit (DermNet).
• Change out of sweaty clothing soon after exercise.
• See a clinician for a red, raw, itchy or smelly rash in the fold, which may need specific treatment (DermNet).

Triggers compared

Trigger	Telltale signs	The fix
Shaving	Bumps, razor burn, nicks; darker after shaving streaks	Wet shave with gel, with the grain, fresh blades; consider laser
Plucking or waxing	Tender follicles, ingrown hairs	Stop plucking; switch methods
Fragranced deodorant	Itch, burning or rash where product goes	Fragrance-free product; patch testing if it persists
Friction and sweat	Worse with workouts, heat or tight sleeves; raw skin in the fold	Dry thoroughly, loose clothing, treat any rash

Sources: Vahabi et al., AAD, Zirwas and Moennich, DermNet.

What to change first

The AAD’s rule for any hyperpigmentation is to find the cause first: when it stops, many spots clear on their own and new ones stop forming (AAD). Change one thing at a time so you know what worked. A practical order:

1. Weeks 1 to 6: switch to a fragrance-free deodorant and fix your shaving technique. These two changes cost almost nothing.
2. Weeks 6 to 12: if things are calmer, add a fading ingredient. In a placebo-controlled trial, 4% niacinamide applied to the underarms improved color within 9 weeks, with a good to excellent response in about a quarter of women ({L(NIA,’Castanedo-Cazares et al.’)}).
3. After 3 months: if nothing has changed, see a dermatologist. Lasers and light devices, such as the Q-switched Nd:YAG laser and intense pulsed light, have the strongest data for stubborn cases (Vahabi et al.).

Expect slow progress. The AAD says a spot a few shades darker than your natural skin usually fades within 6 to 12 months once the trigger is gone (AAD).

Frequently asked questions

Can deodorant cause underarm hyperpigmentation?

It can contribute, mainly when a product irritates the skin or causes an allergic reaction. Deodorants are the leading cosmetic cause of fragrance allergy in patch-testing data (Heisterberg et al.), and inflamed skin can leave pigment behind.

Is shaving or waxing better for dark underarms?

Neither is ideal for irritation-prone skin. Careful wet shaving with a fresh blade is gentler than plucking (AAD); waxing carries a risk of burns and redness (AAD). Laser hair removal reduces the need for both, if done by someone experienced with your skin tone (AAD).

Does antiperspirant darken armpits?

Antiperspirants are classified as drugs and reduce sweat with aluminum-based ingredients; most also contain fragrance (Zirwas and Moennich). Fragrance, not aluminum, is the usual allergen, so a fragrance-free antiperspirant is a reasonable choice if you need sweat control.

How long does underarm hyperpigmentation take to fade?

Usually 6 to 12 months once the cause stops, and longer for deeper discoloration (AAD).

Can friction alone darken underarms?

Yes. Body folds and friction are listed causes of underarm pigmentation (Vahabi et al.), and moisture in the fold makes irritation more likely (DermNet).

Are natural deodorants better for dark underarms?

Not automatically. “Natural” products often get their scent from essential oils, which the deodorant-allergy review counted among the potential allergens in these products (Zirwas and Moennich). For irritation-prone underarms, “fragrance-free” on the label matters more than “natural,” and so does how your own skin reacts over a few weeks.

Sources

1. Vahabi SM, Sajjadi S, Kalantari Y, et al. “Axillary Hyperpigmentation Treatment: A Systematic Review of the Literature.” Journal of Cosmetic Dermatology, 2025. pmc.ncbi.nlm.nih.gov
2. Castanedo-Cazares JP, Lárraga-Piñones G, Ehnis-Pérez A, et al. “Topical niacinamide 4% and desonide 0.05% for treatment of axillary hyperpigmentation: a randomized, double-blind, placebo-controlled study.” Clinical, Cosmetic and Investigational Dermatology, 2013. pubmed.ncbi.nlm.nih.gov
3. Zirwas MJ, Moennich J. “Antiperspirant and deodorant allergy: diagnosis and management.” Journal of Clinical and Aesthetic Dermatology, 2008. pmc.ncbi.nlm.nih.gov
4. Heisterberg MV, Menné T, Andersen KE, et al. “Deodorants are the leading cause of allergic contact dermatitis to fragrance ingredients.” Contact Dermatitis, 2011. pubmed.ncbi.nlm.nih.gov
5. American Academy of Dermatology. “Hair removal: How to shave.” AAD. aad.org
6. American Academy of Dermatology. “6 ways to remove unwanted hair.” AAD. aad.org
7. American Academy of Dermatology. “Laser hair removal: FAQs.” AAD. aad.org
8. DermNet. “Intertrigo.” DermNet. dermnetnz.org
9. American Academy of Dermatology. “How to fade dark spots in darker skin tones.” AAD. aad.org
10. American Academy of Dermatology. “Acanthosis nigricans: Signs and symptoms.” AAD. aad.org

General information, not medical advice. For a spot that’s new, changing or bleeding, see a dermatologist.