Cosalic Ointment 100 gm consists of Salicylic acid (peeling agent) and Coal Tar (keratoplastic). It is used to treat psoriasis and controls seborrheic dermatitis (scaly patches and red skin on the scalp). Salicylic acid is a keratolytic medicine that increases moisture in the skin and dissolves the substance that causes the skin cells to stick together thereby breaking down the clumps of keratin (hair protein), removes dead skin cells, and softens the skin. Coal tar is a keratoplastic (thickens the keratin layers) agent that causes shedding of dead cells from the skin’s top layer and slows down skin cells' growth, decreasing scaling and dryness relieves itchiness.