What is a contraindication for using chemical relaxers on hair?

Using chemical relaxers on hair that is previously damaged or over-processed is a contraindication due to the potential for further damage. Chemical relaxers alter the hair's structure by breaking down disulfide bonds, breaking the hair's natural curl or wave pattern. If the hair has already been compromised from previous processes like coloring or relaxing, it may not withstand the additional stress that a chemical relaxer entails. This can lead to severe hair breakage, loss of elasticity, and overall deterioration of hair health.

In contrast, while freshly dyed hair can also be a concern, it is not as definitive a contraindication as previously damaged hair. Curly or naturally straight hair types, while relevant in assessing the need for a relaxer, do not inherently contraindicate the use of chemical relaxers as they are simply different hair types that might require different approaches rather than an outright restriction. Thus, the most critical factor in this scenario is the previous damage to the hair, which directly affects its ability to endure the chemical process safely.