noun
shampoo
Refers to a shampoo product or preparation, often in a medical or cosmetic context. More technical than the common loanword シャンプー.
医師から洗髪剤を処方された。
The doctor prescribed a medicated shampoo.
The common everyday word for shampoo. 洗髪剤 is more technical and often used in medical or product-label contexts.
Compound of 洗髪 (washing hair) + 剤 (agent, preparation). A straightforward Sino-Japanese coinage.