Your scalp may feel itchy after washing because of leftover shampoo, harsh cleanser, hot water, dry scalp, product buildup, dandruff, seborrheic dermatitis, or contact dermatitis from shampoo, conditioner, dye, or fragrance. To help, rinse longer, use lukewarm water, switch to a gentler shampoo, reduce dry shampoo buildup, and see a dermatologist if itching is severe or persistent.