Ingredient Spotlight: Phenylethyl Resorcinol (SymWhite)

• It’s a phenolic compound derived from pine bark
• The skin benefits of phenylethyl resorcinol include antioxidant and brightening effects
• It addresses uneven tone, dark spots, melasma and post-acne marks
• Phenylethyl resorcinol works by inhibiting tyrosinase activity
• It is safe for skin when used in concentrations below 1%
• It can be paired with most skincare actives including vitamin C

If you have fought dark spots and uneven tone, chances are you came across an ingredient called phenylethyl resorcinol, which also goes by Symwhite 377. According to research, this hard to pronounce guy is thought to be one of the highest melanin suppressors used in skincare formulations, having skin whitening effects twenty times more potent than kojic acid.^[1]

Even more, this resorcinol derivative serves as the primary selling pitch in lots of brightening products coming from the most notable brands like SkinMedica, La Roche-Posay, and Sesderma. Nothing so praiseworthy can pass us by without being noticed. That’s why we scoured the internet and did plenty of research to find everything about phenylethyl resorcinol for skin, its benefits, how safe it is, and the best products containing it.

Intrigued? Keep scrolling.

What is phenylethyl resorcinol?

Phenylethyl resorcinol, also known as Symwhite 377, is a white crystalline phenolic compound derived from pine bark developed to target skin discoloration. As for skincare, phenylethyl resorcinol is a powerful skin whitening agent that acts as an antioxidant and tyrosinase inhibitor, often used to promote a more even-looking complexion.^[1]

FYI, this synthetic compound is produced from resorcinol (hence the name) which is an isomer just like hydroquinone sharing the same molecular formula but a slightly different structure.^[2] In fact, there are quite a few resorcinol derivatives that express brightening and depigmenting benefits, but phenylethyl resorcinol stands as the most researched and tolerable one, along with butyl resorcinol.^[3]

Phenylethyl resorcinol benefits for skin

While resorcinol alone is more used to fight conditions such as acne and dermatitis, phenylethyl resorcinol entered the skincare world as a promising skin lightening agent. When topically applied, its main role is to reduce melanin content in cells by binding to tyrosinase and blocking the enzyme activity responsible for pigment production.^[1][3][6] But the list of benefits goes on as phenylethyl resorcinol is also an antioxidant that helps scavenge free radicals and reduce pigmentation caused by UV exposure.^[1]

Given everything, phenylethyl resorcinol is an excellent compound to brighten your skin and fade existing discoloration — studies suggest that a concentration of 0.5% is as potent as 1% kojic acid.^[4] For the record, during one study, a cream containing phenylethyl resorcinol improved the appearance of uneven tone and reduced hyperpigmentation by up to 43% after a 12-week treatment, making it a great alternative to hydroquinone.^[5]

However, despite all of the above, phenylethyl resorcinol isn’t the easiest ingredient to add to a skincare product since it has poor water solubility and is very susceptible to degradation when exposed to light. The worrying part is that the poor water solubility may limit its absorption into the skin, making it less effective. But luckily, most products use encapsulation systems to boost the delivery and stability of phenylethyl resorcinol, maintaining its perks to the fullest.

Is it safe?

Although phenylethyl resorcinol is considered safe for skin, it can cause irritation when used in concentrations above 1%. It’s also an ingredient that should be avoided during pregnancy and breastfeeding since there’s not enough research to confirm how it reacts in these circumstances.

How to use

Phenylethyl resorcinol in skincare is used in all sorts of products, including creams, toners, serums, and sunscreens, as an antioxidant and skin brightener. It’s also gentle enough to be used daily as a part of your morning and night routines. Due to its low solubility, resorcinol works best when applied to vulnerable skin (like after a dermaroller or chemical peel), which allows more resorcinol to penetrate the skin.

Last but not least, phenylethyl resorcinol can be paired with other skin-lightening actives such as vitamin C, glutathione, kojic acid, retinol, and resveratrol for more intense brightening effects.

Products with phenylethyl resorcinol

Below are the best skincare products infused with phenylethyl resorcinol that work to promote a more radiant and brighter complexion while fading dark spots for a perfectly even skin tone.

• SkinMedica Lytera 2.0 – View on Amazon, $154
• PCA Skin Hydroquinone-Free Pigment Gel – View on Amazon, $64
• La Roche-Posay Pigmentclar Serum – View on Amazon, $50.99
• Allies of Skin Retinal & Peptides Repair Night Cream – View on Allies of Skin, $109
• Sesderma Azelac RU Liposomal Serum – View on Amazon, $52
• Murad Rapid Age Spot Correcting Serum – View on Murad, $78

References

1. Kim BS, Na YG, Choi JH, et al. The Improvement of Skin Whitening of Phenylethyl Resorcinol by Nanostructured Lipid Carriers. Nanomaterials (Basel). 2017;7(9):241. Published 2017 Aug 28. doi:10.3390/nano7090241
2. National Center for Biotechnology Information (2022). PubChem Compound Summary for CID 5054, Resorcinol. Retrieved April 26, 2022 from https://pubchem.ncbi.nlm.nih.gov/compound/Resorcinol.
3. Tokudome, Y.; Hoshi, T.; Mori, S.; Hijikuro, I. Synthesis of Resorcinol Derivatives and their Effects on Melanin Production. Cosmetics 2020, 7, 55. https://doi.org/10.3390/cosmetics7030055
4. Prasetyadi Mawardi, Mardiana (2020) The Difference of Melanin Index in Treatment of Melasma Using Non-Hydroquinone Cream and Kligman’s Formula. Clin Res Dermatol Open Access 7(3): 1-4. DOI: 10.15226/2378-1726/7/3/001116
5. Gold MH, Biron J. Efficacy of a novel hydroquinone-free skin-brightening cream in patients with melasma. J Cosmet Dermatol. 2011 Sep;10(3):189-96. doi: 10.1111/j.1473-2165.2011.00573.x.
6. Kang M, Park SH, Park SJ, Oh SW, Yoo JA, Kwon K, Kim J, Yu E, Cho JY, Lee J. p44/42 MAPK signaling is a prime target activated by phenylethyl resorcinol in its anti-melanogenic action. Phytomedicine. 2019 May;58:152877. doi: 10.1016/j.phymed.2019.152877. Epub 2019 Feb 26.