How many days a course of cefaclor for urinary tract infection takes depends mainly on the site of the urinary tract infection. If it is upper urinary tract infection such as acute pyelonephritis, it may take 10~14 days; if it is lower urinary tract infection such as acute cystitis, it may take 3~7 days. Cefaclor is mainly indicated for respiratory, urinary, ENT and skin and soft tissue infections caused by sensitive bacteria. Urinary tract infections can be divided into upper urinary tract infections, mainly pyelonephritis, and lower urinary tract infections, mainly cystitis, depending on where the infection occurs. In case of pyelonephritis, if the condition is mild, it can be treated with oral medication for 10~14 days; in case of acute cystitis, the course of treatment is usually 3~7 days. If there is no improvement in symptoms for 3 days of treatment, the medication should be adjusted according to the results of drug sensitization. Cefaclor is mostly seen gastrointestinal reactions such as soft stools, stomach upset, loss of appetite, diarrhea, belching (hiccups), allergic reactions such as rash, urticaria, etc., arthralgia, serum aminotransferase and other adverse reactions, allergy to this product and other cephalosporins is contraindicated. It is recommended to use the drug under the guidance of a doctor, not blindly self-medication to avoid adverse effects. Patients with urinary tract infections are advised to go to the regular hospital in time, and standardize the treatment under the guidance of the doctor.