While approved for use in the UK, US, EU, Japan and Australia, hydroquinone is banned as an ingredient to be purchased over-the-counter and doctors are only allowed to prescribe a concentration less than 2% due to the medical implications it can have on the skin and body.

“Hydroquinone is ‘cyto-toxic’ meaning it lightens skin by killing melanin-producing cells within the skin cells,” explains Ada Ooi, facialist and skin expert. “This process can be dangerous, making your skin extremely fragile, and in some cases photosensitive, leading to reverse hyperpigmentation.”

“With prolonged use (or at a concentration over 2%), some may also develop ochronosis (brown pigments that spread and accumulate in connective tissue, creating patches with blueish-black caviar like lesions), which can be further worsened with any sun exposure. Studies have also shown that traces of hydroquinone can be found in the liver and kidneys while some formulations also contain mercury, leading to a higher risk of toxicity.”

It’s important to note that hydroquinone’s dangerous reputation is due to unregulated use – use tied in to high percentages, a prolonged use over a period of months and insufficient SPF protection to prevent sun damage and re-pigmentation in the skin.

Hydroquinone: the return of skincare’s most controversial ingredient