MEDICASP Coal Tar Gel Dandruff Shampoo reduces itching, redness, irritation, flaking and scaling associated with dandruff, seborrheic dermatitis or psoriasis. Helps prevent recurrence of the symptoms of dandruff. Designed to penetrate the scalp, it starts to work on the first day and help prevent recurrence of the symptoms of dandruff. This effective formula features 0.5 percent coal tar. Dermatologists have been prescribing coal tar for more than 100 years to treat scalp psoriasis and dandruff. For best results: use at least twice a week or as directed by a doctor.