All your life, you’ve been told to finish a course of antibiotics, even if you’re feeling better. But now that antibiotic resistance has become such a serious problem, some British doctors are questioning whether that advice is doing more harm than good. 
Health experts from Brighton and Sussex Medical School, the University of Oxford, and other institutions write in an analysis in the BMJ that there is no evidence to support the notion that cutting short a course of antibiotics encourages drug resistance. In fact, they said, it’s taking more antibiotics than needed that leads to resistance.
According to the doctors, the belief that not finishing antibiotics leads to resistance “can be traced back to the dawn of the antibiotic era.” Alexander Fleming, the discoverer of penicillin, spoke in 1945 about a man who didn’t take enough of the antibiotic and passed a now-resistant form of strep throat on to his wife, who died from the infection.
Fleming said at the time:
“If you use penicillin, use enough!”
However, as the doctors note in their analysis, Streptococcus bacteria has never been shown to develop resistance to penicillin. Furthermore, other early observations have yet to be proven by modern research.
Tim Peto, professor of medicine at the University of Oxford and a co-author of the article, said:
“No one has questioned (this advice) for all this time. In the scientific world, it’s an accepted view that there is too much usage of antibiotics and we want to minimize that. We want to only give them to people who need antibiotics to get better.” 
What has been proven, according to the authors of the opinion piece, is that taking antibiotics unnecessarily contributes to drug-resistance. And that’s whether you take them when they’re not needed – such as when you have a viral illness – or if you continue taking them after you feel better. 
As you might imagine, after more than 70 years of patients being told to finish their antibiotics, the topic is extremely controversial. That’s OK, though – the authors don’t want the medical community to immediately implement the new advice. More research is necessary, they said, and even if the advice was implemented, it might not apply to every single person.
“We’re not at all saying that patients should stop when they feel like it or that patients should ignore their doctor’s advice.”
Really, Peto said, there’s “not enough knowledge” for doctors to know how long antibiotics should be prescribed for. That’s why it’s too early to tell people to stop taking their medicine.
You’d think that after more than 7 decades, we’d understand a bit more about antibiotics, though.
A professor of infectious diseases at Imperial College London, Alison Holmes said:
“It remains astonishing that apart from some specific infections and conditions, we still do not know more about the optimum duration of courses or indeed doses in many conditions, yet this dogma has been pervasive and persistent.” 
 The Guardian