Give an antibiotic 3 days to work. Q: On average how long does it take for an antibiotic to start working in a way that symptoms start improving? How long do you have to wait before you decide that an antibiotic is not going to work? If you have any sources to back this up, I will appreciate the links.
For adults, generally 3 days of therapy is the cut off where you decide if an antibiotic is working. Anecdotally, some patients report pain relief after a couple of doses. And I understand some patients actually develop more pain within the first couple of days when bacterial cell lysis occurs and the toxins are released, before feeling better. Generally, three days of therapy before you decide to change antibiotics.
Many Antimicrobial Stewardship Policy (ASP) protocols call for evaluation of empiric therapy at 72 hrs.