Hydroquinone is a skin-bleaching or skin lightening ingredient that may be used anywhere on the face or body to lighten areas of darkened or hyper-pigmented skin such as freckles, chloasma (skin darkening caused by hormones), melasma (general skin darkening) and age spots (sometimes referred to as solar lentigenes).
Preparations containing hydroquinone are only available in certain countries. In most countries including the USA and New Zealand a 2% preparation is available without a prescription. In Canada, however, hydroquinone is available as a 2% or 4% cream for topical application without a prescription and may be purchased from most pharmacies.
Hydroquinone works by decreasing the production and increasing the breakdown of melanosomes
(melanin pigment granules) in the skin's pigment cells (melanocytes). Melanin and melanocytes are responsible for skin coloring. Hydroquinone does this by inhibiting the activity of tyrosinase, the enzyme needed to make melanin.
In most cases, some skin lightening will be apparent after 4 weeks of treatment. Though it may take longer to see complete results, generally within 8 to 12 weeks. If no skin lightening effect is seen after using a hydroquinone product after 3 months, then treatment should be discontinued.
You can maximize the effectiveness of hydroquinone by staying out of the sun, wearing protective clothing or using a broad spectrum UVA/UVB SPF 15 or higher sunscreen when outdoors. Because protection from the sun is so important when using a hydroquinone preparation, you may want to consider purchasing a hydroquinone preparation with UVA/UVB protection for use during the day and one without for use at night. Alternatively, you may purchase one product without SPF and combine it with a really good sun blocker that contains active ingredients like Mexoryl SX, Mexoryl XL, Titanium dioxide, Avobenzone, Tinosorb .
Hydroquinone should be used regularly until desired results are achieved. Use after that should be as required to maintain results. If no improvement is seen within 4 to 6 months, treatment should be discontinued.