Hello Clarithromycin is a macrolide type of antibiotics and used for the treatment of respiratory infection skin infection , eradication of H PYLORI and many infections. It never causes any discoloration of urine or don t develop blood in urine i.e. presence of blood in urine is not due to clarithromycin . The possibilities of blood in urine may be due to these reasons, these include: 1 Renal calculus , diagnosis can be confirmed by ultrasound of renal system. 2 Renal impairment , diagnosis can be confirmed by blood examination for urea , serum creatinine level 3 The least possible cause is side effect of this drug. In my opinion first of all stop this drug . Still blood present in urine ( 6-8 hours after stopping of drug ) then consult a physician and get his opinion. At present no need of any ER consultation. Take plenty of fluid , water and juice . Hope this will help you. Good luck.