What are the effects of long-term hydroquinone use?

The effects of hydroquinone include difficulty breathing, hives, inflammation of body parts such as the tongue and lips, blisters, and skin discoloration, according to Everyday Health. Users of hydroquinone may also experience a severe skin-burning sensation on the skin, and severe skin dryness and cracking.

Patients should cease using hydroquinone and seek immediate medical attention when these side effects appear, notes Everyday Health. Using hydroquinone according to doctor's instructions may help to avoid bad results.

Hydroquinone is a medication that lightens the dark skin resulting from conditions such as old age, melasma and chloasma, and works by disrupting the melanin production process. However, it is not safe for people who are allergic to peroxide or hydroquinone.