Hair dyeing may lead to skin allergy because hair dye contains many chemicals, and patients may be sensitive to one, or several, of the ingredients in hair dye. If they are highly sensitive to at least one of these ingredients, contact with the skin may lead to allergy, resulting in irritation, often manifested as redness, dryness, itching, oozing and flaking, clinically known as contact dermatitis. Therefore, a skin test needs to be done behind the ear before hair dyeing, and hair dyeing should be avoided if allergy symptoms appear. If allergy occurs during hair dyeing, you need to stop using such hair dyes and rinse your hair with plenty of water to remove as much of the dye left on the hair shaft as possible to minimize the damage to the skin from the dye. If there is oozing, local treatment with boric acid solution, or saline solution wet compresses is needed. In addition, oral antihistamines, such as oral loratadine tablets, or levocetirizine hydrochloride tablets, can be used to relieve the symptoms of allergy. For more severe symptoms, glucocorticoids should be administered for anti-allergy and anti-itch treatment. Pay attention to a light diet and avoid eating, no alcohol, no spicy and stimulating food, more rest, no excessive fatigue, no late nights, etc. Drinking more water to promote metabolism can speed up the discharge of toxic substances.