Hello, unfortunately, you haven t provided enough information - for example: why does he take clindamycin? Clindamycin does not directly cause nose bleeding. Rarely, it may cause thrombocytopenia which may predispose to nose bleeding. Since he s having protracted bleeding, checking his clot producing mechanisms may be indicated. I usually ask my patients to do the following: bleeding time, complete blood count, INR (or prothrombin time) and aPTT. This is a basic check of both the platelet functionality and the clotting mechanism. An ENT specialist should be consulted as well, to check the nostrils. I hope I ve answered your question. Please let me know if you need further assistance. Kind Regards, Dr Panagiotis Zografakis, Internal Medicine Specialist