Reader question: Can I use Kojic acid cream to treat my facial skin hyperpigmentation, after I stop using hydroquinone and tretinoin in combination? Will it cause any problems? Like, can it be bad for skin of colour? Will skin become black because of stopping hydroquinone?
Both have their primary mechanism of action in common: Hydroquinone works by inhibiting the activity of tyrosinase (an enzyme necessary for melanin production), and so does kojic acid.
But HOW hydroquinone and kojic acid stop tyrosinase from working is drastically different. Hydroquinone acts as a melanocyte cytotoxic inhibitor and increases the cytotoxicity of melanocytes (melanin-producing cells). In other words, hydroquinone works by increasing cell death amongst cells that produce melanin.
On the other hand, kojic acid incites the skin cells to form a complex. In turn, this skin cell complex stops tyrosinase from working.
Getting Similar Results from Kojic Acid and Hydroquinone
If you want to get similar results from kojic acid as you have been getting from hydroquinone, you want to use 4% kojic acid in conjunction with 10% glycolic acid. According to a study by scientists Ellis and Garcia, 4% kojic acid combined with 10% glycolic acid was more effective than 4% hydroquinone alone for the treatment of hyperpigmentation.
For best results, I recommend using a glycolic acid cleanser, toner, or serum, followed by a kojic acid serum or moisturizer. I am particularly liking Peter Thomas Roth 10% Glycolic Solutions Moisturizer or our own FutureDerm Customizable Day Serum with 10% glycolic acid plus 4% kojic acid.
If You’re Worried About Ochronosis…
If you’re concerned about ochronosis, or the darkening of the skin from hydroquinone use that is caused by a build-up of phenylalanine or tyrosine, you are likely to notice it WHILE you are using hydroquinone — not after its discontinuation.
Ochronosis is also rare in general. A literature review by Dr. Jacob Levitt of exogenous ochronosis and clinical studies employing hydroquinone (involving over 10,000 exposures under careful clinical supervision) reveal an incidence of just 22 cases in the U.S. in more than 50 years.
One thing to keep in mind when transitioning off of hydroquinone is you do NOT want to transition straight to resorcinol. Combining the two has been associated with ochronosis.
Ochronosis may also be the result of excess sun exposure while using hydroquinone, as hydroquinone tends to thin the skin, making it more photosensitive, but the sun in turn increases melanin production, reducing the effects of hydroquinone. As such, hydroquinone should always be used with a sunscreen.