First and foremost that Hydroquinone should be used cyclically – not more than 4 months in one cycle. Your skin should rest of hydroquinone with such great ingredients like kojic acid, azelaic acid, arbutin, and other natural & healing lightening agents (especially if you have darker skin).
Hydroquinone works by blocking the tyrosinase enzyme, which is responsible for the melanin production – skin pigment. As long as you continue using hydroquinone, your tyrosinase enzyme blocked, and hence skin dark pigment production.
Never use simultaneously any other products containing benzoyl peroxide & resorcinol while you are using products containing hydroquinone.
Not allow hydroquinone to get anywhere near your eyes.
Hydroquinone has NOT been directly linked to cancer in humans — only mice, Hydroquinone is likely not a cancer-causing agent. Dr. David J. Goldberg, a clinical professor of dermatology at the Mount Sinai School of Medicine states, “Over 100 scientific articles confirm hydroquinone is a safe topical for humans; no independent studies prove the opposite.”