Scalp suddenly very itchy may be caused by allergies, may also be seborrheic dermatitis or folliculitis and other manifestations, need to be specifically analyzed. 1. Allergy: patients in a new shampoo or use hair coloring cream after the scalp itching and large red spots, wind, considering an allergic reaction caused by contact dermatitis, to stop using shampoo or hair coloring cream in a timely manner, to carry out regular anti-allergy treatment. 2. Seborrheic dermatitis or folliculitis: patients in addition to itchy hair will have very oily hair, dandruff and other symptoms, is due to the patient’s sebaceous gland secretion is too exuberant, blocking the mouth of the hair follicle caused by the timely treatment, usually eat a light diet, eat less greasy food. Patients feel very itchy scalp may also be fungal infections, head lice and other causes, it is recommended that patients go to the hospital, combined with medical history and other tests to determine, symptomatic treatment.