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Author: Vanessa Ngan, Staff Writer, 2005.
In New Zealand, hydroquinone is registered as a Pharmacy Only medicine in creams containing hydroquinone in concentrations up to 2%. Some doctors' offices may sell other brands with concentrations up to 4%.
Hydroquinone works by decreasing the production and increasing the breakdown of melanosomes in melanocytes. It does this by inhibiting the activity of tyrosinase, the enzyme needed to make melanin.
In most cases, lightening of skin should be seen after four weeks of treatment. Sometimes it may take longer to see any change, but if no bleaching effect is seen after three months of treatment, you should stop using hydroquinone.
It is important to use hydroquinone regularly as directed until you achieve the desired bleaching, after which use as needed to maintain results.
Hydroquinone cream is usually well tolerated. Some users may experience minor and temporary skin irritations including mild itching or stinging and reddening of the skin (irritant contact dermatitis). If these do not subside, stop using the cream.
Side effects that should warrant stopping the cream and seeking medical advice immediately include severe burning, itching, crusting, or swelling of treated areas (possible allergic contact dermatitis) and any unusual skin discolouration.
Prolonged use of hydroquinone has been associated with the development of exogenous ochronosis (a persistent blue-black pigmentation), especially in Africa, but this is rare. It might be due to other ingredients such as phenol, resorcinol and antimalarial agents, which are known to cause ochronosis.
Do not use benzoyl peroxide, hydrogen peroxide, or other peroxide products when using hydroquinone. Temporary dark staining of the skin may occur. If accidentally used together, wash the skin with soap and water to remove the staining.
Hydroquinone creams may contain sodium metabisulphite that may cause serious allergic reactions (including anaphylaxis) in certain susceptible people.
Hydroquinone should not be used in pregnancy or when breastfeeding.
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