How long does it take for an unopened hair relaxer to go bad?

I bought one about a year ago and I need to put it in, but it doesn't have an expiration date on the box or any of the bottles. Generally, how long does it take for one to go bad.How long does it take for an unopened hair relaxer to go bad?
I'd through it out if it's been a year. I read on a message board where someone said she bought a relaxer off a beauty supply store shelf that had obviously been sitting there for a long time because it was covered in dust and when she used it it didn't get her hair straight - it had basically lost it's effectiveness over time. This is the same brand and strength she always uses so she knows it work well for her hair.





Also, there should be a phone number on the literature that came with the relaxer that you can call for questions, so you can call that number and ask them.How long does it take for an unopened hair relaxer to go bad?
The ingredients what are in your drain cleaner are the same ones in a relaxer.