Hi, I Am 53, Female, Around 70kg, An My Dentist

Hi,
I am 53, female, around 70kg, an my dentist changed my medication from doxycycline (after five days without getting better) to azithromycin ... but forget to mention when I should start. I've taken 200T one tablette (its maximum dose, as far as I know.)
There is no interaction, thats waht I know now ... but, how about sideeffects.
Sorry for my english, I am german.
Greetings ...