Topiucal drug therapy is an intuitively sound approach to the management of skin diseases. Depositing medication at the site of disease involvement is potentially effective and reduces systemic exposure. Topical drugs are absorbed usually by passive diffusion. In clinical practice, the choice of an optimized formulation that will be effective and well tolerated is essential. Data confirm that patient adherence with therapy leads to better outcomes and lower long-term treatment costs, while poor adherence is directly linked to poor treatment outcomes and and patient dissatisfaction. Local cutaneous irritation, which may be linked to components of the formulation and/or to the active drug itself, is a common cause of non-adherence. Well-designed drugs are important in the management of acne vulgaris and acne rosacea. Formulators have sought to improve treatment efficacy and tolerability by several different techniques, such as delayed release of the active drug, fixed combinations of two different molecules, or incorporating ingredients into the formulation vehicle that improve epidermal barrier function and offset the irritating effects of the active drugs.