Wash the neck daily with a gentle cleanser
Exfoliate 1–2 times per week with a mild chemical exfoliant
Use a moisturizer with urea, lactic acid, or glycolic acid
Apply sunscreen to the neck every day
Avoid friction from tight collars, necklaces, or harsh scrubbing
Keep the area dry and clean
Use topical products with niacinamide, vitamin C, or retinoids
Maintain a healthy weight if excess weight is a factor
Check blood sugar levels if darkening is sudden or persistent
See a dermatologist if the darkening does not improve or spreads