Using expired hair relaxer can have adverse effects on your hair and scalp. When a hair relaxer has passed its expiration date, its ingredients may have degraded, making the product less effective or even harmful. This can cause the relaxer to not work properly, leaving your hair in an unevenly processed state. In some cases, using expired hair relaxer can lead to hair damage, breakage, scalp irritation, or even chemical burns.
It is important to always check the expiration date of hair products before using them to ensure their efficacy and safety. If you inadvertently use an expired hair relaxer and experience any negative reactions, it is best to immediately stop using the product, rinse your hair thoroughly, and consult a professional hair stylist or a dermatologist for advice on how to treat any resulting issues.