What are the risks of using bleaching creams?

Bleaching Creams. Common reactions to topical hyrdoquinone include contact dermatitis which is an allergic reaction, dryness, fissuring, erythema, burning, and irritation. Exogenous ochronosis, is a condition in which bluish black pigmentation of sun exposed skin has been seen after long term exposure to hydroquinone. Many doctors feel it should not be used more than 6 months.
Mercury. Some creams may contain mercury or other toxic substances.