Ryan Turner, MD, of Turner Dermatology in NYC, says that melasma will be the most difficult of the hyperpigmentation types to treat because it's linked to hormones. "Melasma is a difficult type of hyperpigmentation to treat because it is caused by certain hormonal influences and chronic sun exposure," he says. "The hormonal changes of pregnancy and the use of oral contraceptives can bring on or worsen melasma." Post-inflammatory hyperpigmentation results from physical trauma to the skin like a scrape, rash, or stubborn acne breakout. It may even appear following certain in-office treatments like strong lasers and peels. Sun-induced hyperpigmentation, or sunspots as they're not-so-lovingly known to the layman, is the result of photoaging from chronic sun damage.