There are some skincare ingredients that the body can build a resistance to over time. One of these ingredients is hydroquinone, which is considered the gold standard for lightening hyperpigmentation.
Hydroquinone, a tyrosinase inhibitor, can stop working when your body gets used to it. The body regulates enzyme production, and after about three months, the body increases tyrosinase production to essentially override the intended effects of the hydroquinone.
Dermatologists recommend giving your skin a break from hydroquinone every three to four months so you can continue to see spot-lightening results.