<prompt> A 17 year old girl with Acne has been taking a drug for the last two years. Show now presents with blue black pigmentation of nails. The likely medication causing the above pigmentation isTetracyclineMinocyclineDoxycyclineAzithromycin  <response>: B i.e. MinocyclineAmongst tetracyclines tetracycline minocycline doxycycline pigmentation is most commonly associated with minocyclineQ. A diffuse blue-blackblue- gray muddy hyper pigmentationQ is an uncommon but troublesome side effect of prolonged minocycline therapy. Sites of involvement include sun exposed skin, mucus membranes eg conjunctiva, nails, teeth, sclera, thyroid bonesQ.Two side effects unique to minocycline are drug induced lupus blue black pigmentation. Tetracycline induced nail discolouration is yellow. 