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%.
How does hydroquinone work?
Hydroquinone works by decreasing the production and increasing the breakdown of melanosomes (melanin pigment granules) in the skin's pigment cells (melanocytes). It does this by inhibiting the activity of tyrosinase, the enzyme needed to make melanin.
How effective is hydroquinone?
In most cases, lightening of skin should be seen after 4 weeks of treatment. Sometimes it may take longer to see any change but if no bleaching effect is seen after 3 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 only as needed to maintain results.
How to use hydroquinone
- Test for skin sensitivity before using by applying the cream to a small patch of hyperpigmented skin. If no redness or itching occurs within 24 hours, begin treatment.
- Clean and dry the skin before applying a thin film of cream twice daily to the area(s) in need of bleaching. Rub into the skin well.
- Apply just enough to cover the affected areas and avoid applying to normal skin, as this will lighten as well. Hence wash your hands after applying unless these are areas of treatment.
- Do not apply near the eyes, mouth, and other mucous membranes.
- Avoid using other medicated topical products (particularly peroxide products) on the same area at the same time unless directed to do so by your doctor.
- When using non-medicated cosmetics, sunscreens, and moisturising lotions, apply hydroquinone first, then wait several minutes before applying them over the top.
Side effects of hydroquinone products
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. A 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.