What is hydroquinone?

Hydroquinone is a skin lightening agent, usually used in preparations to help treat areas of skin with “hyperpigmentation” (dark patches), such as in melasma. This is a skin condition in which areas of brown or greyish patches appear, mainly on areas of the face exposed to the sun, such as the cheeks, forehead, upper lip, bridge of the nose and chin. It can occasionally also affect other areas of the body, such as the neck and forearms. Although men can also experience it, it’s more common in women, especially during pregnancy, hence the name “mask of pregnancy”. The exact cause of melasma is not known, but it is thought to be caused by melanocytes – the pigment-generating cells in the skin – producing too much melanin. Melanin is the natural pigment which gives skin its colour, and helps protect it from the sun.

Hydroquinone is the most commonly used treatment of melasma and is the gold standard treatment in hyperpigmentation skin conditions. It can either be used alone or in combination with other ingredients such as steroids and retinoids (retinoic acid and tretinoin – derivatives of vitamin A). It should not be used during pregnancy, as it can harm the unborn baby.

Hydroquinone is a prescription only medicine, so it should only be prescribed by a medical doctor. Over the counter products containing hydroquinone are illegal in the UK, as they can result in serious side effects if used incorrectly. These products can also contain harmful substances, such as mercury. Make sure you read the ingredients of any products before you buy it over the counter and avoid buying it if it contains hydroquinone.

How does hydroquinone work?

Hydroquinone helps lighten the skin by stopping melanocytes from producing melanin. By controlling melanin levels, the skin becomes more evenly toned.

How to use hydroquinone?

Your doctor will advise you on the correct use of your hydroquinone-containing cream. It’s usually recommended to apply a thin layer to the affected area of the skin twice a day.  You should avoid any of the surrounding skin getting into contact with the cream and be sure to wash your hands before and after application. Hydroquinone should only be used for limited periods of time, usually three or four months and no more than six months of continuous use. Your doctor will advise you on how long your treatment should last for.

As sun exposure causes skin affected by hyperpigmentation to darken more than the surrounding skin, it’s also important to help protect your skin by avoiding the sun where possible, wearing protective clothing and using a sunscreen. This should be a broad-spectrum sunscreen, effective against both UVA and UVB, with a sun protection factor (SPF) of at least 30 or preferably 50.

Is hydroquinone safe?

In 1982, the US Food and Drug Administration (FDA) established hydroquinone as an ingredient that is generally safe and effective. However, in 2006 the FDA proposed to ban over the counter products containing hydroquinone from the market over safety concerns, pending further investigations. One of the reasons for the proposed ban include reports of cases of ochronosis, a medical condition in which the skin becomes darker. Another reason is that some studies showed that hydroquinone can cause cancer in rodents, such as rats and mice, when given via the oral route over a long period of time. 

Hydroquinone use has been widespread for decades, and no cases of skin cancer have been reported to date. Its link to other types of cancer reported in rodents, hasn’t been proven or reproduced in humans either. In terms of ochronosis, data from the US shows a very low incidence of 22 cases over a period of 50 years. The majority of the other reported cases originate from Africa, where there are several factors which can amplify reports of ochronosis. The formulations (the mixture of ingredients used to make a product) used often contain agents which increase the absorption of hydroquinone, making side effects more likely.  The products can also contain other ingredients which are known to cause ochronosis, such as resorcinol. Some studies have suggested that many of the side effects experienced are due to misuse, excessive use and the application of multiple products at the same time. Moreover, many of the products used contain contaminants, such as mercury, which is toxic and can cause several ill effects to human health. 

13 years on, it’s still not known whether the FDA will implement the ban, as hydroquinone products are still available over the counter in the US. These can contain up to 2% hydroquinone without a prescription. Products on prescription can contain up to 4% hydroquinone. 

In the EU, hydroquinone use in cosmetics has been banned in 2001 based on concerns over side effects to the skin, such as the already mentioned ochronosis. This ban in cosmetics is appropriate as hydroquinone can lead to serious side effects if used inappropriately. Hydroquinone is a medicinal product in the UK, which should only be prescribed and used under the supervision of a medical doctor. 

So, if you choose to use hydroquinone, make sure you avoid any over the counter products, as these are illegal in the UK and can contain other contaminants such as mercury and steroids. Speak to your doctor instead, they can prescribe a suitable hydroquinone product and advise you on how to use it appropriately.   

Hydroquinone side effects

As with all medicines, hydroquinone can cause side effects, but this doesn’t mean that everyone will get them. Possible side effects include mild skin irritation, stinging, redness and itching. In rare cases, it can cause ochronosis, causing the skin to become darker, which is the reason hydroquinone should only be used for a few months at a time. 

How effective is hydroquinone?

Hydroquinone is effective in the treatment of hyperpigmentation conditions, such as melasma. A study of patients with melasma found that 79% of those treated with 4% hydroquinone showed an improvement after a duration of 12 weeks treatment. 
You may start seeing an improvement after four weeks of consistent use. Though, it can take several months before the product starts working. If you haven’t seen any improvement within three months of treatment, it’s unlikely that it’ll work for you and you should discuss this with your doctor.

Can I use hydroquinone if I’m pregnant or breastfeeding?

You shouldn’t use hydroquinone if you’re pregnant, as it could harm the unborn baby.There isn’t enough information on the use of hydroquinone whilst breastfeeding. You should therefore avoid using it if you’re nursing. Speak to your doctor for further advice.

What else can I do to help protect my skin?

So, if you have dark patches on your skin, the most important thing you can do is to try and avoid excessive exposure to sunlight, as well as protect your skin from UV radiation. Make sure you also avoid using sun lamps and sun beds.

Exposure to sunlight can reverse the effects of hydroquinone. So, protecting yourself from the sun will also help your treatment be more effective.
Here are some top tips to stay safe in the sun:

• Spend time in the shade when the sun’s rays are at their strongest. This is between 11am and 3pm in the UK
• Cover your skin with loose-fitting cotton clothing 
• Wear a wide brim hat and sunglasses
• Use a broad-spectrum sunscreen with an SPF of at least 30 against UVB and a UVA star rating of 4 or 5
• Sunscreen is not an alternative to protective clothing and staying in the shade but an additional protection measure

Sources

• Gupta AK et al. The treatment of melasma: A review of clinical trials Journal of the American Academy of Dermatology 2006; 55(6): 1048-1065
• J. Levitt. The safety of hydroquinone: A dermatologist’s response to the 2006 Federal Register. Journal of the American Academy of Dermatology 2007;57(5):854-72
• https://www.who.int/ipcs/assessment/public_health/mercury_flyer.pdf
• https://www.ncbi.nlm.nih.gov/pubmed/18027166
• https://ec.europa.eu/health/scientific_committees/consumer_safety/docs/sccs_o_169.pdfhttps://ntp.niehs.nih.gov/ntp/noms/support_docs/hydroquinone_may2009.pdf
• https://www.theguardian.com/world/2018/apr/23/skin-lightening-creams-are-dangerous-yet-business-is-booming-can-the-trade-be-stopped
• https://www.govinfo.gov/content/pkg/FR-2006-08-29/pdf/E6-14263.pdf
• http://www.bad.org.uk/shared/get-file.ashx?id=169&itemtype=document
• https://www.guysandstthomas.nhs.uk/resources/patient-information/pharmacy/creams-to-depigment-your-skin.pdf
• https://www.nhs.uk/conditions/cosmetic-procedures/skin-lightening/