Do I always have to take the full course of antibiotics?

The question

I'm so confused. My doctor has said I should always take all my pills when I'm prescribed an antibiotic. But I read a recent news report that says patients might be able to stop taking their medication when they are feeling better – and not continue until last pill is finished. I know this is related to the problem of antibiotic resistance. But why the flip-flop?

The answer

It turns out that the forces driving antibiotic resistance are a bit more complicated than once thought. So, it's worthwhile reviewing how our understanding of this process has recently evolved.

For decades, doctors have urged patients to take every pill because they want to be sure the bacteria causing an infection have been eradicated. They're primarily concerned that if some bacteria remain, the surviving microbes might bounce back and be even harder to treat.

Exposure to antibiotics – especially when prescribed inappropriately – can certainly contribute to the development of stronger strains of bacteria.

It's a classic case of a Darwinian struggle – "survival of the fittest." When the hardier strains survive and proliferate, they pass on their drug-resistant genes to their offspring. Over time, patients need stronger antibiotics, or longer-duration therapy, to quell infections. The ultimate fear is that we may eventually run out of effective, life-saving antibiotics.

So, there is some logic to finishing a course of antibiotics.

But, in recent years, some experts have become increasingly concerned about the "collateral damage" done by a course of antibiotics. In particular, the drugs don't just kill the microbes causing the infection – they also attack other bacteria in the body.

There are literally billions of bacteria inhabiting the gut, skin, mouth and urinary tract. Most of these microbes don't normally cause us harm. Many are beneficial. For example, some aid in the digestion of food.

However, when these so-called "good" bacteria are exposed to antibiotics, they can also develop resistance to the drugs. Studies show that all bacteria have the remarkable ability to share their genes with other microbes in the body. As a result, drug-resistance that has developed in beneficial bacteria can be later transmitted to potentially harmful bacteria.

To minimize the risk of this happening, we need to use antibiotics appropriately.

That means using just enough of an antibiotic to control the infection – but not so much that resistance develops.Being this precise is a challenge partly because there is not a lot of good evidence about how long we should treat many common infections. To make matters worse, in the past, doctors tended to overprescribe antibiotics – erring on the side of more is better.

Microbiologists and infectious-diseases specialists are well aware of the lack of data on the best treatment durations.

A few weeks ago, some of these experts in Britain decided to sound the alarm to the wider medical community by publishing an article in the BMJ (formerly known as the British Medical Journal), under the provocative headline, "The antibiotic course has had its day."

They argue that patients should no longer be always told to finish their antibiotics. In some cases, they can stop when they are feeling better.

"The concept of an antibiotic course ignores the fact that patients may respond differently to the same antibiotic," they write. "In many situations, stopping antibiotics sooner is a safe and effective way to reduce antibiotic overuse."

Reaction to the article has been mixed. Some medical organizations say they are not yet ready to change the usual advice given to patients. Others welcome the debate.

"Could we get away with shorter treatments? Maybe. We don't always know," says Dr. Andrew Simor, chief of microbiology and infectious diseases at Sunnybrook Health Sciences Centre in Toronto. He notes that doctors have a very good idea how long patients should be treated for some infections. Tuberculosis, for instance, requires at least a six-month course of antibiotics. But for many other conditions, "we really don't know what is the minimum safe and effective treatment," Simor adds.

If nothing else, the paper highlights the need for more research, says Dr. Allison McGeer, a microbiologist at Mount Sinai Hospital in Toronto.

Yet who will pay for clinical trials? Tests need to be carried out on a wide range of conditions and different antibiotics, some of which have been on the market for many years and are no longer under patent to a single company, McGeer says.

Simply put, there is no financial incentive for the pharmaceutical industry to fund such research – especially when it could result in patients taking fewer drugs.

And, even though antibiotic resistance is seen as one of the biggest threats facing public health, it's still hard to convince research-granting agencies to pay for trials in this area, McGeer laments.

So, what is the bottom-line message for patients? Simor emphasizes that patients should not stop an antibiotic, even if they are feeling better, without first talking to their doctor.

"There should be a dialogue between the patient and the prescriber," he says. That way, "the patient can understand the expected risks and benefits of abbreviating a course of therapy."

Paul Taylor is a patient navigation adviser at Sunnybrook Health Sciences Centre. He is a former health editor of The Globe and Mail. You can find him on Twitter @epaultaylor and online at Sunnybrook's Your Health Matters.