Hydroquinone is another skin-lightening ingredient that can lighten your overall skin tone. Dr. Imahiyerobo-Ip calls it a "gold standard for addressing hyperpigmentation" because it works well on stubborn skin discoloration. "It decreases the formation of melanin in the skin that is responsible for your skin's pigment," said Dr. Nussbaum. "Hydroquinone-based products are typically used to lighten areas of darkened skin such as freckles, age spots, and melasma (caused by hormones, sun, and genetic factors)."
But with the effectiveness of this powerful ingredient comes a few risks. "Because it inhibits all pigment production, it may result in unwanted lightening on normal skin," said Dr. Imahiyerobo-Ip. The safety of hydroquinone has long been debated by the FDA but in 1982 it was deemed OK to be sold over the counter in concentrations up to two percent — anything higher than that requires a prescription.
Still, the ingredient is controversial to say the least.