Conditions · Pigment

Dark Underarms

Axillary hyperpigmentation is usually post-inflammatory, driven by friction, shaving and irritation — not by lack of washing.

Mechanism

What is actually happening

Repeated mechanical and chemical irritation produces low-grade inflammation, which stimulates melanocytes. Acanthosis nigricans is a separate, thicker, velvety change with different implications.

The distinction

How it is told apart

Post-inflammatory darkening is flat. Acanthosis nigricans is thickened and velvety, and is associated with insulin resistance — so the texture, not just the colour, is what is assessed.

Assessment

What is established first

Texture as well as colour, hair removal method, deodorant and product history, friction from clothing, and BMI or metabolic history where acanthosis is suspected.

Approach

What is typically done

Removing the source of irritation is the part that lasts. Where treatment is appropriate, gentle pigment-directed approaches are used, with settings adjusted for a thin, frequently irritated site.

When treatment waits

When it is deferred

If the change is velvety and thickened rather than flat, the metabolic question is raised before any cosmetic treatment.

Frequently asked

What is dark underarms?

Axillary hyperpigmentation is usually post-inflammatory, driven by friction, shaving and irritation — not by lack of washing.

How is dark underarms told apart from similar conditions?

Post-inflammatory darkening is flat. Acanthosis nigricans is thickened and velvety, and is associated with insulin resistance — so the texture, not just the colour, is what is assessed.

What is assessed before treating dark underarms?

Texture as well as colour, hair removal method, deodorant and product history, friction from clothing, and BMI or metabolic history where acanthosis is suspected.

When is treatment deferred?

If the change is velvety and thickened rather than flat, the metabolic question is raised before any cosmetic treatment.

Have this assessed

Every assessment is carried out personally by Dr Sin Yong, Medical Director. 9 Scotts Road, #12-01 Pacific Plaza.

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