Methylchloroisothiazolinone
The question

Is Methylchloroisothiazolinone safe in shampoo?

AvoidShampoo

A synthetic preservative, normally blended with methylisothiazolinone, that is a potent skin sensitizer implicated in the same contact-dermatitis epidemic.

What the research flags

  • The methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) blend is a widely used preservative for which a considerable increase in cases of contact dermatitis has been recorded, prompting calls for stricter legislation (Leiva-Salinas 2014, PMID 24626102)
  • Tested at the older 100 ppm concentration, up to 50 percent of contact-allergy cases can go undetected, indicating a potent sensitizer that is easy to under-diagnose (Leiva-Salinas 2014, PMID 24626102)
  • MCI/MI allergy formed part of the 2010 to 2015 global epidemic that peaked in 2013 and 2014 (Ozkaya 2020, PMID 32691417)

Regulatory
IARC Class: NL

Other shampoo ingredients on file

Sources & references

  1. [1]
    Peer-reviewedPubMed / NCBI — pubmed.ncbi.nlm.nih.gov · ref 24626102
  2. [2]
    Peer-reviewedPubMed / NCBI — pubmed.ncbi.nlm.nih.gov · ref 32691417

Research disclaimer: Ratings reflect peer-reviewed research and regulatory assessments available at the time of publication, not the dose or formulation of any specific shampoo product. This is not medical advice.