What is this for? I've been given 1g azithromycin to take tonight which is a pretty high dose to take all at once. Last time I had erythromycin it made me really ill and I absolutely have to get to a nurse appointment tomorrow to sign forms and get our drugs. Do I really need to take this? I have to take metronidazole tonight as well but wasn't told why I need to take all of these antibiotics.