- Mechanism of action: hydroquinone inhibits activated tyrosinase activity (therefore it does not act on normal skin).
- A word on available concentrations:
- 2%: often ineffective
- 3-5%: good bleaching agent
- 6-10%: higher concentrations can cause irritation
- Side effects:
- Contact dermatitis (Both Allergic and Irritant)
- Nail Discoloration
- Exogenous Ochrnosis can rarely occur in dark skin individuals only (reports show exogenous ochronosis in Chinese patients of lighter skin types)
- How does Exogenous Ochronosis occur ?
- Hydroquinone (HQ) inhibits homogentisic oxidase
- This leads to the accumulation of homogentisic acid
- Dangers with Hydroquinone (HQ) usage:
- Systemic absorption
- Exogenous ochronosis
- Carcinogenesis
- Occupational Vitiligo
Bibliography: Katsambas A (Conflicts of Interest: Abbott, Janssen-Cilag, Leo Pharma, Merck, Schering-Plough). Melasma: Pathogenesis and Treatment. 70e Réunion annuelle de l’AAD (American Academy of Dermatology) – San Diego, California, United States of America (USA)
Source of information: here