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What do you think are the best skin-brightening ingredients in skin care products?
Brightening the skin means addressing all kinds of potential problems: hyperpigmentation, melasma, dark age spots, dullness, and general discolorations. Provided that someone is otherwise healthy, some ingredients that will brighten the skin include:
What hydroquinone is used for: Since 1982, hydroquinone has been FDA-approved for the treatment of freckles, melasma, and general brown patching. Today, hydroquinone is the most commonly used bleaching agent in the United States.
How hydroquinone works: Hydroquinone works in two distinct ways: 1.) inhibiting tyrosinase, the rate-limiting enzyme of melanin (i.e., pigment) production, and 2.) increasing the cytotoxicity of melanocytes, the melanin producing-cells.
Risks: Unfortunately, hydroquinone has been banned in some countries, including France and South Africa, for concerns about increased cancer risk and ochronosis (darkening of the skin) with its use. Yet I have yet to encounter an American dermatologist who believes hydroquinone in skin care products increases cancer risk. Dr. Susan C. Taylor, M.D., a Philadelphia-based dermatologist, states, ”The maximum levels of hydroquinone currently allowed (2 percent for over the counter, 4 percent for prescription) aren’t dangerous. At worst, it might cause redness or irritation, but only if your skin is sensitive or allergic to the medication.” (Elle, October 2007). Dr. Jacob Levitt, M.D. also reviewed the existing studies on hydroquinone and concluded “topical applications of hydroquinone in standard product concentrations are not carcinogenic to humans” (Journal of the American Academy of Dermatology, 2006), and Dr. David J. Goldberg, a clinical professor of dermatology at the Mount Sinai School of Medicine, agrees, “Over 100 scientific articles confirm it is a safe topical for humans; no independent studies prove the opposite.” (Elle, October 2007).
As for ochronosis, a paradoxical darkening of the skin that is caused by a build-up of phenylalanine or tyrosine, that may be a small, though legitimate, concern for those with darker skin tones (American Journal of Clinical Dermatology, 2001). Dr. Jacob Levitt reviewed 10,000 cases of hydroquinone use over the course of 50 years, and found just 22 cases of ochronosis amongst them, yet all involved patients of color (Journal of the American Academy of Dermatology, 2006). The reasons for ochronosis occurrence in patients with darker skin are not clear. However, increased risk of ochronosis have been linked to using hydroquinone with resorcinol (an agent often used to treat postinflammatory inflammation) and to excess sun exposure while using hydroquinone. As such, always use hydroquinone without resorcinol and with a sunscreen.
Where to find hydroquinone: Tri-Luma, a prescription strength retinoid (0.5% tretinoin) steroid (0.01% fluocinolone acetonide) and hydroquinone (4%) has been shown to be effective in treating melasma and general darkening of the skin over the course of eight weeks. According to Dr. Audrey Kunin, M.D., a Kansas-City based dermatologist, Tri-Luma should not be used for longer than eight weeks, as the steroid component may cause the skin to become thinner (and hence more photosensitive and prone to sun-induced signs of aging, etc.). Some other prescription hydroquinone treatments available in the U.S. are Lustra (4% hydroquinone, 4% glycolic acid), Lustra-AF (4% hydroquinone, 4% glycolic acid, SPF 15), and Alustra (4% hydroquinone and retinol).
2. Kojic acid
What kojic acid is used for: Kojic acid is used for similar purposes as hydroquinone: freckles, melasma, and general brown patching. In fact, kojic acid is often used in cycles with hydroquinone (four weeks of kojic acid only, four weeks hydroquinone only).
How kojic acid works: Kojic acid lightens the skin solely by inhibiting the activity of tyrosinase in a unique pathway involving catecholase inhibition. It has been found to be less effective than 2% hydroquinone (Journal of Cosmetic Dermatology, 2001) and more effective than arbutin (Medscape, 2009).
Risks: Kojic acid has been found to be associated with contact allergy, as it has a high sensitizing potential (Dermatologic Surgery, 2001). Despite the fact many companies reduce manufacturing of kojic acid to 1%, kojic acid still has sensitizing effects at 1% (Contact Dermatitis, 2006).
The good news is when we are living in an age when we want skin care ingredients “safe enough to eat,” kojic acid is regularly ingested as a component of soy sauce, miso, sake, or as a food additive preventing the browning of strawberries. The strange news is, kojic acid produces convulsions when it is injected into the skin (Regulatory Toxicology and Pharmacology, 2001). So don’t be expecting kojic acid injections any time soon!
Last word of note: kojic acid will break down upon exposure to heat and light, so store yours in a cool, dark place.
3. Glycolic acid
What glycolic acid is used for: mottled pigmentation, skin dullness, fine lines, surface roughness, freckles, lentigines, and to treat actinic and seborrehic keratosis
How glycolic acid works: As the most commonly used alpha hydroxy acid, glycolic acid advance desquamation and exfoliation of the top layer of the skin. As a result, glycolic acid quickens the rate of cell turnover, decreases small wrinkles and increase fibroblast proliferation of collagen. It does not specifically inhibit melanin production, like hydroquinone or kojic acid.
Risks: A lot of people experience irritation after at-home glycolic acid peels, for two main reasons. First, glycolic acid sensitizes the skin, such that the skin is more likely to be irritated by other ingredients used in conjunction with glycolic acid (Skin Therapy Letter, 1998). Second, glycolic acid has been associated with skin burns and ulcerations, so it is important to speak with a dermatologist first to see which strength is appropriate for you (International Journal of Cosmetic Science, 2007).
4. Vitamin C
What vitamin C is used for: Sunspots, skin dullness, UV-induced erythema and sunburn, increase skin firmness (mild effect), decrease wrinkle depth (mild effect).
How vitamin C works: Vitamin C inhibits tyrosinase, an enzyme in melanin production (Cosmetic Dermatology, Burgess, 2008).
Risks: Risks associated with topical vitamin C use are rare and few side effects have been reported. Probably the biggest risk is not storing vitamin C properly. While most of the ingredients listed on this page are sensitive to light and heat, vitamin C in particular becomes far less ineffective when exposed to air, light, and heat. Another risk of using vitamin C is not selecting the right form of vitamin C. Different forms include L-ascorbic acid, ascorbyl glucoside, magnesium ascorbyl palmitate, and ascorbyl glucosamine. My favorites are L-ascorbic acid (high concentrations are available) and ascorbyl glucoside (found to be absorbed well into the skin).
I choose azelaic acid over ascorbyl glucosamine for hyperpigmentation, as 20% azelaic acid has been shown to be more effective than 5% ascorbyl glucosamine in treating solar lengitines (Dermatology, 2002). For more on the different forms of vitamin C, please see my Spotlight On: Vitamin C post.
What LumixylTM is used for: freckles, melasma, and general brown patching
How LumixylTM works: Stanford University researchers recently developed LumixylTM, a complex of oligopeptides (0.1% w/w) that has been found to significantly inhibit tyrosinase, the rate-limiting enzyme in melanin production. According to a 2009 study in The Journal of Drugs in Dermatology, LumixylTM improved melasma and overall facial aesthetics in five female participants – a significant finding in such a well-controlled study, though the sample size was small.
Risks: The product was released in 2009, so very few studies of noted side effects have been conducted thus far.
Where to find Lumixyl: Participating physicians’ offices; please visit the official LumixylTM website.
Required FTC Disclosure: I was mailed a sample of Lumixyl in August 2011. However, my original glowing review of Lumixyl was in September 2009, so that’s proof I don’t let samples influence my written opinions.
6. Azelaic acid
What azelaic acid is used for: Same as hydroquinone – freckles, melasma, and general brown patching. Sometimes azelaic acid is used in place of kojic acid in hydroquinone four-week alternating periods. Azelaic acid works as an acne treatment, and, to a lesser extent, a rosacea treatment.
How azelaic acid works: Take a guess – yep, you got it, azelaic acid also inhibits tyrosinase. According to a double-blind study in the International Journal of Dermatology, over the course of six months, a 20% azelaic acid cream yielded good or excellent results in 65% of patients.
In fact, according to the same study, 20% azelaic acid had “no significant treatment differences” observed when compared to 4% hydroquinone (the prescription level) with regard to overall rating, reduction in lesion size, and pigmentary intensity.
Risks: Side effects, such as allergic sensitization or exogenous ochronosis (associated with hydroquinone) were not observed with 20% azelaic acid (International Journal of Dermatology, 2007).
Other Posts You May Enjoy
- What are the Best Skin Brightening Cosmetics?
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- Spotlight On: Azelaic Acid
- Spotlight On: Vitamin C
- Brazilian Peel Review
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