Which products should be avoided on hair that has been previously permed with ammonium thioglycolate?

Hair that has previously been permed with ammonium thioglycolate is affected by the chemical processes involved in perming. Ammonium thioglycolate is a reducing agent used in the perming process that alters the chemical structure of the hair. It creates curls or waves by breaking the disulfide bonds in the hair strands and reforming them into a new shape.

Sodium hydroxide is an actively strong alkaline substance used in certain types of relaxers. The application of sodium hydroxide to hair that has already been treated with ammonium thioglycolate can lead to over-processing. These two types of chemical treatments can cause excessive damage to the hair, potentially leading to breakage or severe hair deterioration. Therefore, sodium hydroxide should be avoided on hair previously treated with ammonium thioglycolate because the combination can create an unsafe and damaging environment for the hair's integrity.

The other products listed, such as aloe vera gel, glycerin, and coconut oil, are generally safe for use on chemically-treated hair. They are often used for their moisturizing and conditioning properties, making them suitable for maintaining the health of hair post-perm.