What is acne: development of acne due to follicular hyperkeratinization, microbial colonization with. Propionibacterium acnes, sebum production and inflammatory mechanism involving innate & acquired immunity: development of comedones (pilosebaceous glands that have developed a keratin plug). The keratin in plug becomes oxidized, resulting in a blackhead or open comedone. When block is deeper, a skin-coloured papule or closed comedone develops. As lesion progresses, cytokines are released causing transformation into an inflammatory papule which develops a central pustule. If inflammatory lesion ruptures below dermis, a cyst or nodule ensures- scarring. Drug induced: comedonal/inflammatory: hormonal (steroids, ocp, halogens (iodide, bromide, b2, b6, b12 vitamins, tb meds (isoniazide, ethambutol, antiepileptics (phenytonin, dilantin, cyclosporine, azathioprine. Improving appearance of lesions in a month: control & alleviation of lesions. Bpo or topical retinoids considered a first-line options for mild-moderate acne. Topicals could be applied to entire affected zones to prevent development of new lesions.