HQ has a 12-h half-life and therefore the recommended application is twice a day. While it can be used to treat focal areas, it is often best to apply this agent to the whole face and apply a heavier amount over the darkest regions.
Based on an oxidation rate constant for the reaction of hydroquinones with alkylperoxy radicals (RO2•) of 1*10^6 (M*sec)^(-1) and an average environmental concentration of RO2• near surface of 1*10^(-9) M, the half-life of hydroquinone in sunlight exposed natural waters is calculated to be 12 minutes.
Hydroquinone is applied topically just to the hyperpigmented skin only, twice daily for 3 months, after which time many patients maintain their improvement by using it twice each week. If there has been no benefit after 3 months of treatment, then the hydroquinone should be stopped.
Hydroquinone may prove beneficial for a maximum of five to six months. Once you stop using it, you may experience irritation on the affected parts of your body. This may lead to inflammation. This inflammation may be dangerous as your skin then begins to build resistance to the treatment after a certain time.
► Hydroquinone may cause a skin allergy. ► Long term exposure may affect the liver and kidneys. OSHA: The legal airborne permissible exposure limit (PEL) is 2 mg/m3 averaged over an 8-hour workshift.
Side effects that you should report to your doctor or health care professional as soon as possible: severe burning, itching, crusting, or swelling of the treated areas. unusual skin discoloration.
We recommend taking a 2 month break after 3 months of application. Since hydroquinone is a photosensitive agent, It is also important to use SPF 30 or higher daily when on hydroquinone.
It's not meant for long-term use, as it might actually make the skin darker, which is a strange effect. It's recommended to take breaks from using it to prevent overuse and a side effect called exogenous ochronosis.
Worse still, ochronosis is particulary hard to treat and in some cases may not be reversible. This is one of the reasons that hydroquinone is a prescription only medicine in many countries.
Hydroquinone has a pretty short shelf life. After a couple of months, it can start to break down and lose its potency, meaning it becomes less effective.
Apply hydroquinone in a thin layer to affected areas of the face. Do not apply it to other areas of the face; otherwise, it will bleach that skin.
Alternative lightening agents including mequinol, arbutin, kojic acid, and others have shown comparable efficacy to hydroquinone in treating hyperpigmentation with less concerning side effects.
HQ is most often used at concentrations of 2-4% [16]. Studies have demonstrated that hyperpigmentation conditions respond very well to 2% HQ, and while higher concentrations are effective, they may cause adverse effects such as skin irritation [16].
Hydroquinone is a skin-bleaching agent that is used to lighten areas of skin. Hydroquinone works by decreasing the production and increasing the breakdown of melanosomes in melanocytes. In most cases, lightening of skin should be seen after four weeks of treatment.
Hydroquinone (HQ), a hydroxyphenolic derivative of benzene, occurs naturally as an ingredient in various plant-derived foods and beverages, such as vegetables (e.g., onions), fruits (particularly cranberries, blueberries, and pears), grains (especially wheat, wheat germ, and rice), coffee, tea, beer, and red wine.
The hydroquinone should be applied twice daily for 2–6 months. If no results are seen after 2 months, it should be discontinued. Therapy beyond 6 months is not expected to yield additional improvement when positive results are seen.
This disease entity may be first noticed in newborns as their urine may be darker than normal. People are often without symptoms until later in life when the skin, sclera (white part of the eye), ears, and nose may develop pigmentary changes. Ear wax of a person with ochronosis will also be dark in color.
The effect of hydroquinone on skin pigmentation is reversible. If you stop, the melanocytes affected by treatment start to resume normal activity, causing the blemishes or spots to gradually reappear.
Melasma is a symmetric progressive hyperpigmentation of the facial skin that has a predilection for darker skin phenotypes. [1] Exogenous ochronosis (EO) is an uncommon disorder characterized by the deposition of microscopic, ochre-colored pigment in the dermis, giving rise to a blue-black hue in the skin.
Rarely ochronosis - ochronosis is a blue-black or gray-blue discoloration; it is rare and more commonly seen in patients that use a high concentration of hydroquinone for a long period on large areas of the body.
Even worse, inappropriate use can cause paradoxical darkening called ochronosis. Additionally, hydroquinone rebound hyperpigmentation can occur if treatment is stopped too early (its best to stay on it for at least 3 months) or when there is sudden cessation or reduction of hydroquinone use.
To reduce this risk, doctors often recommend “cycling” Hydroquinone. This means using it for a limited period followed by a break.
Although it was originally believed that only high concentrations of hydroquinone were causal, there have been reports of ochronosis after use of 2% hydroquinone preparations.
Duration of hydroquinone use is considered the most important factor for the development of ochronosis [2,12], with EO reported to develop after the extended use of hydroquinone [1,13-15]. Lazar et al. reported that patients used topical hydroquinone for an average of 9.2 years before developing EO [11].