One of the most vexing antibiotic-related questions is: “Should you finish the course of antibiotics that the doctor has prescribed you?”

My colleague and I were asked just that when we were interviewed by 938Live Body & Soul’s Daniel Martin recently.

The conventional answer has generally been: “Yes, you should finish every single dose, even if you feel well”. This advice is given even with the understanding that all over the world, approximately a third of doctors prescribe antibiotics inappropriately, either by prescribing antibiotics when they are not indicated (i.e. for viral upper respiratory tract infections) or by prescribing the wrong antibiotics (a relative was recently prescribed moxifloxacin – a powerful fluoroquinolone – for a stye) or by prescribing overlong courses of antibiotics (i.e. 7 to 10 days of antibiotics for an uncomplicated urinary tract infection). In our hospitals, there is still an obsession with multiples of 7 when it comes to antibiotic duration (i.e. 14 days of antibiotics for bacteraemia; 6 weeks for treating intra-abdominal abscesses, etc), even though several of us understand that these numbers are essentially “magical”.

An interesting study published in JAMA, modelled after the Israeli parole judges’ story, showing that antibiotic prescriptions in GP clinics increased over the course of a day (improving slightly after lunch).

Many – both physicians and non-healthcare staff – even believe that failing to complete the prescribed course of antibiotics would lead to antibiotic resistance developing. This is of course completely wrong. The more antibiotics one consumes, the more likely it is that resistance develops.

Screen capture from Medscape – Prof Brad Spelling debunking the myth that every dose of antibiotic prescribed should be consumed.

The alternative, which is to question the decision of the prescribing doctor, was felt to lead to even worse repercussions. Imagine if patients failed to follow doctors’ advice on a regular basis or frequently challenged doctors!

But we feel that the population now largely understands that doctors are not infallible, and that medicine is messy. Doctors in general have to navigate large gaps in evidence and diversity of practice. It is fair that doctors should be questioned if they seem to be overly keen to prescribe antibiotics, and patients should also be free to ask doctors if they should really finish their course of antibiotics if they are already well. As Prof Spelling puts it, doctors “should not fear customising the duration of therapy“.