Underarm hyperpigmentation is one of the most common pigmentation concerns in Indian patients — and one that is frequently not brought up in consultations because patients consider it cosmetic or inevitable. It is neither. In most cases it has a treatable underlying cause, and the pigmentation itself responds well to appropriate treatment.

Why It Happens

The most common cause is post-inflammatory hyperpigmentation from repeated friction and irritation — from shaving, depilatory creams, tight clothing, and the natural friction of the skin fold. Each minor insult triggers a small inflammatory response that, in Indian skin with its high melanocyte activity, translates into pigmentation over time. Acanthosis nigricans — a velvety, diffuse darkening associated with insulin resistance — is another frequent cause, particularly in patients who are overweight or have PCOS or prediabetes. In these cases, addressing the underlying metabolic condition is as important as treating the skin itself. Deodorants and antiperspirants containing alcohol, fragrances, or baking soda can also cause chronic contact irritation and secondary pigmentation.

What Works

The first step is addressing the cause: switch to a gentle depilatory method (laser hair reduction is the most effective long-term solution for friction-based pigmentation as it eliminates the primary insult), switch to a fragrance-free, alcohol-free deodorant, and wear breathable, non-restrictive clothing. Topical treatments — azelaic acid, kojic acid, tranexamic acid, and niacinamide — reduce melanin production in the area. Retinoids accelerate cell turnover and enhance depigmentation. Superficial chemical peels applied to the underarm produce faster clearance for established pigmentation. For acanthosis nigricans, metabolic management must accompany skin treatment or results will be temporary. Laser treatments — Q-switched laser and fractional laser — are options for treatment-resistant cases.

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— Dr. Nishita Ranka | Consultant Dermatologist | Dr. Nishita’s Clinic for Skin, Hair & Aesthetics, Hyderabad