Does Hair Dye Go Bad Once Opened?
Hair dye does not necessarily go bad once opened, but it can expire and lose its effectiveness over time. Most hair dyes have an expiration date that indicates when it is no longer safe or effective to use. It is also important to note that if the dye has been exposed to humidity, heat, or sunlight, it can deteriorate faster and lose its effectiveness. If you are unsure whether your hair dye is still safe to use, it is best to check the expiration date and consult with the manufacturer’s instructions.