Recently we looked closely at the most famous of the whitening agents, hydroquinone – it’s the most studied and very effective, but has some serious (though often overstated) side effects, is irritating to the skin, and has been heavily restricted in some countries as well. Today let’s have a look at some of the other whitening agents on the market – how do they work, and what are the side effects?

The most commonly used topical treatments for treating hyperpigmentation are usually hydroquinone or retinoids, which are quite irritating to the skin. Therefore a lot of people turn to alternative whitening agents. Although many of these haven’t been studied extensively, they appear in many products and appear to be quite safe.

Note that clinical studies are almost always done on patients who have quite severe hyperpigmentation, such as melasmas and dyschromias – not the target audience of this post (if your hyperpigmentation is severe, you should discuss your specific situation and treatment options with a dermatologist). This means that the results mightn’t entirely translate to the mild freckling, acne scarring and sun damage that the average beauty junkie is looking to reduce.

How do lightening products work?

Whitening agents work in a number of different ways, and some work in more than one way. Lightening products generally slow down melanin production.

Most treatments for hyperpigmentation act on the first step of melanin synthesis – the conversion of tyrosine into DOPA and dopaquinone by an enzyme called tyrosinase. They can either:

1. act as a mimic of tyrosine, essentially keeping tyrosinase too busy to produce as much melanin as before (hydroquinone, mequinol, azelaic acid, arbutin, licorice extract)
2. block off the important copper ions in tyrosinase, preventing the enzyme from working (kojic acid)

Some other ways ingredients reverse or slow down hyperpigmentation are:

• slowing down the production of tyrosinase enzyme (N-acetylglucosamine)
• undoing the reaction that tyrosinase does (ascorbic acid)
• slowing down maturation of melanosomes (pigment producing organelles) (arbutin and derivatives)
• preventing melanin pigment from travelling from the melanocytes where it’s made, to the keratinocyte skin cells (soy, niacinamide, retinoids)
• dispersing pigment (licorice extract)
• increasing skin turnover, meaning there are more skin cells being produced, and less pigment to go around (alpha and beta hydroxy acids, retinoids)

In general, side effects are less of a concern for the less effective ingredients; however, combining different whitening agents results in a more potent product without too much irritation.

Mequinol (4-Hydroxyanisole)

Mequinol is the main alternative prescription alternative to hydroquinone. It’s also known as methoxyphenol, hydroquinone monomethyl ether, and p-hydroxyanisole.

How it works: It’s not entirely clear how mequinol works, but it seems that it’s similar to hydroquinone in that it mimics tyrosine and decreases tyrosinase’s ability to make melanin pigment.

Strength: Mequinol usually comes at a concentration of 2%, sometimes in combination with 0.01% tretinoin and ascorbic acid to enhance penetration. It’s been found to be as effective as hydroquinone.

Irritation potential and side effects: It’s supposed to be less irritating than hydroquinone, but can sometimes cause temporary postinflammatory hyperpigmentation. There has also been some instances of reversible depigmentation.

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