With sensitivities being caused with methylchloroisothiazolinone/ methylisothiazolinone (MCIT/MIT) leading to ban in Europe in 2017 and the negativity against formaldehyde releasers and parabens among consumers, phenoxyethanol has emerged as a common preservative not only in personal care but also taking over the home care and color cosmetic space.[1,2] Phenoxyethanol or chemically 2-phenoxyethanol is a liquid prepared by reacting phenol with ethylene glycol or ethylene carbonate. It is naturally present in avocado, endive, tea and species of mangifera plant and can be present in the formulation as a fragrance ingredient.
Multiple mechanisms have been stated for preservative efficacy of phenoxyethanol
1. Membrane damage
Leakage of cytoplasmic content
2. Reduced cell growth
Inhibition of DNA and RNA biosynthesis
Disruption of proton gradient
Reduced energy metabolism
Blends with other preservatives, for example, MCIT/MIT, diazolidinyl urea, organic alcohols and acids, chlorophenesin have been developed to reduce the effective concentration of individual compounds while enhancing their efficacy. To further enhance its efficacy at lower doses, mixtures with boosters, like, ethylhexylglycerin have also been tested. It has been suggested that the potentiation effect is due to the surfactant properties of ethylhexylglycerin, reducing the surface tension at the bacterial cell wall and improving the contact between phenoxyethanol and the membrane. In a set of studies, phenoxyethanol was found to be useful in the treatment of chronic inflammatory periodontal disease alone or in combination with chlorhexidine, leading to lowered doses of chlorhexidine and reduced chances of tooth staining due to the latter.
Phenoxyethanol has been found to be safe in high doses. It is rapidly absorbed into the blood circulation upon topical application and is excreted in the urine along with its major metabolite phenoxy acetic acid. [1,2] The Scientific Committee on Consumer Safety recommends concentrations up to 1% in formulations. There have been some reports on urticaria and contact dermatitis upon exposure to skin care products containing phenoxyethanol. Its level in baby care products especially those for children <3 years should be monitored as there are some rare reports of its effects on nervous system of babies.
Overall, due its extensive use even in home care products, there may be multiple levels of exposure to phenoxyethanol resulting in contact allergy.
1. Cosmetic Ingredient Review Expert Panel. Opinion of the Scientific Committee on Consumer Safety (SCCS) - Final version of the opinion on Phenoxyethanol in cosmetic products. Regul Toxicol Pharmacol. 2016;82: 156.
2. Scognamiglio J, Jones L, Letizia CS, et al., Fragrance material review on 2-phenoxyethanol. Food Chem Toxicol. 2012;50 Suppl 2: S244-55.
3. Langsrud S, Steinhauer K, Lüthje S, et al., Ethylhexylglycerin Impairs Membrane Integrity and Enhances the Lethal Effect of Phenoxyethanol. PLoS One. 2016;11(10): e0165228.
4. Wilson M, Bansal G, Stanley A, et al., Susceptibility of Oral Bacteria to Phenoxyethanol and Phenoxyethanol/Chlorhexidine Combinations. J Periodontol. 1990;61(8): 536-41.