Precautions and Contraindications
Hydroquinone is a skin bleaching agent that may produce unwanted cosmetic effects if not used as directed. The physician should be thoroughly familiar with the use, adverse effects, and precautions and contraindications of hydroquinone before prescribing or dispensing the drug. Hydroquinone should not be used for the prevention of sunburn.
Hydroquinone should not be applied near the eyes; to cut, abraded, or sunburned skin; after shaving or using a depilatory agent; or over miliaria rubra (prickly heat). One manufacturer recommends that small amounts of the commercially available 2 or 4% hydroquinone preparations be applied to an area of unbroken skin about 25 mm in diameter prior to depigmentation therapy with the drug to assess the risk of irritation or allergic reactions. The test site is examined after 24 hours; minor redness is not a contraindication, but if itching, vesicle formation, or excessive inflammation occurs, treatment with the drug is not advised. Alternatively, some clinicians recommend use of an extemporaneously prepared 1% hydroquinone in petrolatum ointment to test for allergy. If rash or irritation develops during hydroquinone therapy, treatment should be discontinued, the drug washed off, and a physician consulted.
Since minimal exposure to sunlight may reverse the bleaching effect of hydroquinone, unnecessary exposure to sunlight should be avoided during and after therapy. If hydroquinone preparations which do not contain sunscreen agents are used during the daytime, sunscreen agents and/or protective clothing should be used to minimize exposure and prevent repigmentation of treated areas; alternatively, these preparations should be used only at night (and the usual preventive measures employed during the daytime), or daytime use of preparations containing sunscreen agents may be considered. After reduction of hyperpigmentation and during maintenance therapy, use of sunscreen agents and/or protective clothing should continue.
Some commercially available topical formulations of hydroquinone contain sulfites that may cause allergic-type reactions, including anaphylaxis and life-threatening or less severe asthmatic episodes, in certain susceptible individuals. The overall prevalence of sulfite sensitivity in the general population is unknown but probably low; such sensitivity appears to occur more frequently in asthmatic than in nonasthmatic individuals.
Hydroquinone is contraindicated in patients with a history of sensitivity or allergic reaction to the drug or any ingredients in the commercially available preparations.