IS THERE A Link between sulfa allergy and shampoo?

No, there is no known link between sulfa allergy and shampoo. There are many different ingredients used in shampoos and none of them are related to sulfa or sulfonamides.

Sulfa allergy is an adverse reaction to medications containing sulfonamide, a class of synthetic antibacterial and antimicrobial agents. While some shampoos may contain sulfates, such as sodium lauryl sulfate (SLS) or sodium laureth sulfate (SLES), these substances do not contain sulfonamides and therefore do not cause allergic reactions in people with sulfa allergies. SLS and SLES are commonly used surfactants in personal care products and detergents, and they can cause skin irritation or dryness in some individuals, but this is not related to sulfa allergy.