Post-inflammatory Hyperpigmentation appears as flat, discoloured spots. It is usually a result of excess Melanin production during the skin's healing process after inflammation or injury.
Ascorbic Acid, the purest form of Vitamin C is effective in inhibiting the enzyme Tyrosinase, which prevents Melanin production. It significantly lightens pigmentation and does not lighten normal skin. Check out The Ordinary - Vitamin C 23% + HA Suspension.