Stop shaving too closely; use a clean, sharp razor and shaving gel
Switch to waxing, trimming, or laser hair removal if shaving causes irritation
Avoid deodorants or antiperspirants with alcohol, fragrance, or harsh chemicals
Use gentle, fragrance-free cleansers on the underarms
Exfoliate lightly 1–2 times per week with a mild chemical exfoliant like lactic acid or glycolic acid
Moisturize daily with a gentle, non-irritating lotion
Apply niacinamide, azelaic acid, kojic acid, or vitamin C products to the area
Use a retinoid at night if tolerated
Wear loose, breathable clothing to reduce friction
Keep the area dry and reduce sweating when possible
Avoid frequent rubbing or scrubbing of the underarms
Treat any rash, infection, or ingrown hairs promptly
Maintain a healthy weight if friction from skin folds is contributing
Consider seeing a dermatologist if the darkening is sudden, severe, itchy, thickened, or persistent
Get checked for insulin resistance, diabetes, or hormonal issues if recommended by a doctor
Use sunscreen on exposed underarms when wearing sleeveless clothing
Be consistent with treatment for several weeks to months