Low-level efficacy of cosmetic preservatives

Research output: Contribution to journalJournal articleResearchpeer-review

  • M D Lundov
  • J D Johansen
  • C Zachariae
  • Lise Moesby
Preservation using combinations of preservatives has several advantages. This study shows that the concentration of some of the most frequently used allergenic preservatives can be markedly lowered when they are combined with phenoxyethanol. The antimicrobial efficacy of cosmetic preservatives and known allergens of various potency [diazolidinyl urea, methylchloroisothiazolinone/methylisothiazolinone (MCI/MI), methylisothiazolinone (MI) and phenoxyethanol] was tested alone and in various combinations of two or three preservatives together. The preservatives were tested for minimum inhibitory concentration (MIC) values and possible synergy using fractional inhibitory concentration. MCI/MI was the only preservative showing low-level MIC against all four tested microorganisms: Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans and Aspergillus niger. Different combinations of the preservatives indicated additive effects against the microorganisms. No combination of preservatives showed any inhibitory action on each other. Challenge tests with different concentrations and combinations were performed in a cosmetic cream. Diazolidinyl urea and MCI/MI alone were ineffective against C. albicans in a challenge test at concentrations up to 16 times higher than the observed MIC values. When combining phenoxyethanol with either one of the allergenic preservatives diazolidinyl urea, MCI/MI or MI, the cosmetic cream was adequately preserved at concentrations well below the preservatives' MIC values as well as 10-20 times below the maximum permitted concentrations. By using combinations of preservatives, effective preservation can be achieved with lower concentrations of allergenic preservatives.
Original languageEnglish
JournalInternational Journal of Cosmetic Science
Issue number2
Pages (from-to)190-6
Number of pages7
Publication statusPublished - 2011

    Research areas

  • Anti-Infective Agents, Candida albicans, Cosmetics, Humans, Microbial Sensitivity Tests, Preservatives, Pharmaceutical, Pseudomonas aeruginosa, Staphylococcus aureus
  • Former Faculty of Pharmaceutical Sciences

ID: 38100112