Exacerbation of renal failure associated with doxycycline.

Doxycycline has been considered a safe broad-spectrum antibiotic for patients with renal failure. Although doxycycline possesses many of the metabolic properties of the tetracycline group, toxic blood levels usually do not occur because of the drug's unique extrarenal route of excretion. We report here a patient with stable chronic renal failure whose renal function acutely and reversibly deteriorated coincident with a 14-day course of doxycycline.