Guanidine Carbonate Relaxers

Young woman with thick brown curly hair
Photo: Jeanette Dietl/Shutterstock
Q: Approximately a year and a half ago I relaxed my hair with {brand name omitted} Relaxer. I'm not African-American. I'm Caucasian, but I have very thick and very curly dark brown hair. The product contains guanidine carbonate. I now want to chemically straighten my hair with {brand name omitted} straightener, but it says not to use it if you've used relaxers containing guanidine carbonate.
Has it been long enough that I can worry-free straighten my hair with the straightener and not get fried, dried-out hair? What is the "cut-off" for whether or not it's been long enough? If not, what can I do? Any advice would be greatly appreciated!

A: Okay! You CANNOT use thio-based straighteners on hair that has been treated with guanidine carbonate or hydroxide relaxers. Since it has been a year and a half ago, if you have been having your hair regularly cut and your hair is less than 8 inches long, you are probably safe.
The problem you will face if you have any portion of the hair that has been treated with the guanidine carbonate relaxer is that portion of the hair will be badly burned by the application of thio-straightener. The hair that has been grown since the application of the relaxer should respond as expected.
So you have to ask yourself about the status of your hair. If you have not had your hair cut since the relaxer application, then the lower portions of your hair are susceptible to damage from using a thio-straightener. You can opt to cut the affected ends off and use the thio-straightener, or simply repeat the use of the relaxer product used before.
The only other option would be to use a flat-iron to straighten the hair daily.
See also:
Hair straightening
Permanent hair straightening
The CHI transformation system
Thermal reconditioning and hydroxide straighteners