Which hair condition cannot use a sodium hydroxide relaxer?

• A. Bleached hair or permed with ammonium thioglycolate
• B. Very dark hair
• C. Thick hair
• D. Short hair

Answer: (A)

Sodium hydroxide relaxers are a very strong alkaline treatment that permanently breaks and reshapes disulfide bonds in the hair. If the hair has already been chemically altered by bleaching or by a perm using ammonium thioglycolate, its bonds and cuticle are already compromised and the hair is more porous. Introducing another aggressive chemical relaxer at this point can push the damage too far, leading to severe overprocessing, breakage, or uneven texture. That’s why bleached hair or hair previously relaxed with ammonium thioglycolate cannot safely use a sodium hydroxide relaxer.

The other conditions—very dark hair, thick hair, or short hair—don’t by themselves indicate a chemical history that would make this relaxer unsafe. They’re not contraindications; the key factor is prior chemical processing and the resulting integrity of the hair.