I'm on azithromycin for 3 days for cough,etc. but 2marow i have a dentist apt.for cleaning and need to take amoxicillin because of new knee any effect?

No: in fact Azithromycin is used for Dental Prophylaxis in patients with Penicillin/amox allergies Hope this is helpful\ Dr Z

Don't double up: The Azythromycin may be all that you need for both situations. Call the Dentist and discuss ALL the meds you are taking. Let Dentist decide 1. Which antibiotic would be best (DDS/DMD may want to talk tis over with your MD?DO), and also whether Dentist wants to put your visit off until after you're free from whatever is causing you to cough.

YES, need it: The bacteria in the mouth become antibiotic resistant within a very short period of time when taking an antibiotic. An alternate antibiotic should be given, in addition to the one already being taken, to provide adequate prophylaxis against resistant organisms. If you are already taking Azithromycin then the antibiotic of choice for joint prophylaxis is Clindamycin.

Find a better DR: And educate your dentist. Azithromycin is seldom useful for "cough". The idea of taking amoxicillin before dental procedures to prevent infection of a total knee has long been discarded. You might just as well take antibiotic every time you brush your teeth. The American Dental Association recommends against this silly use of an antibiotic which can cause allergies and C. Diff. Infections in these

No need to change : There's no need to change antibiotics either one will cover adequately for prosthetic prophylaxis.