If you suspect you have a urinary tract infection (UTI), there’s no doubt ... With doxycycline, only a limited amount of the drug enters the urine compared to other treatment options.

Renal impairment (CrCl 15–30mL/min): reduce dose by ½; CrCl <15mL/min: not recommended. Not for group A β-hemolytic strep. Avoid prolonged administration. Monitor CBCs, urine, and renal function.