Urinary tract infections: Do antibiotics help?

Three or more days of antibiotics almost always ensure that the symptoms of an uncomplicated urinary tract infection will go away quickly. Taking antibiotics over five days or more can get rid of the last of the bacteria causing the infection, but the longer the treatment, the more adverse effects there are.

Uncomplicated urinary tract infections (UTIs) like cystitis are most common among young women: on average, they will get this kind of infection every one or two years. UTIs are caused by bacterial infections. They are usually associated with burning pain when passing urine, and often make people need to go to the toilet much more often too. These symptoms can be very unpleasant, but the infection will rarely lead to any serious health problems. More serious complications might arise if, for instance, bacteria reach the kidneys and lead to a kidney infection (pyelonephritis). Then people have other symptoms too, such as kidney pain, fever, chills, nausea and vomiting. UTIs can also be a more serious problem if they keep coming back, which happens in some women.

Different women deal with UTIs in very different ways. Some wait a few days to see whether the symptoms go away on their own, or follow common tips such as drinking a lot, or emptying their bladder straight after having sex. Many women decide to take antibiotics to try to get rid of the unpleasant symptoms.

Antibiotics help in the treatment of UTIs

Antibiotics can quickly relieve the symptoms of UTIs and clear up the infection by killing the bacteria. This was proven in trials where one group of people took antibiotics and another group used a placebo (dummy drug). You can read why it is important to do research in this way to get reliable results here. The trials showed that people who took antibiotics felt better a lot sooner. The pain and burning went away fast – usually within 1 to 3 days. At the end of the treatment, which lasted between 1 and 7 days, 62 out of 100 women no longer had any symptoms (62%). In comparison, only 26 out of 100 women (26%) who took a placebo were free of symptoms at the end of treatment.

Some women had adverse effects while taking antibiotics. These included gastrointestinal (stomach and bowel) problems such as nausea and diarrhea, as well as headaches, rashes and itching. The trials did not provide any data about whether taking antibiotics helps against UTIs in the long term.

Different antibiotics lead to similar symptom relief

A group of researchers from the Cochrane Collaboration – an international network of researchers – wanted to find out how well the different antibiotics work compared to each other when used to treat UTIs. They summarized the results of all the good-quality trials in a systematic review. You can read more about this kind of research here.

The researchers found that all of the drugs they looked at had a similar benefit. This is true for conventional antibiotics as well as quinolones. Quinolones are a type of antibiotic but they work in a different way: they block the action of a particular enzyme which the bacteria need to live. The most suitable medication in an individual case will depend on various factors. For example:

• Are there any reasons why someone cannot use a particular antibiotic, for instance because they are allergic to it, cannot tolerate it, or are pregnant?
• Are some antibiotics more likely to have certain adverse effects than others?
• How sensitive are the bacteria to the different antibiotics?
• Are there known cases of resistant bacteria?

Resistant bacteria are bacteria that do not react to particular antibiotics. Bacteria can become resistant if, for instance, antibiotics are used too much. You can read more about this problem and how to use antibiotics safely here.

Taking antibiotics for three or five days

Symptoms can even be relieved by a single high-dose antibiotic, as was used up to a few years ago. That one-off therapy got rid of the symptoms quickly, but there were often enough bacteria left over for the infection to return. So today UTIs are treated using either a three-day short course or a longer course of antibiotics (five days or more).

To answer the question whether it is best to take the shorter or longer course of antibiotics, researchers from the Cochrane Collaboration analyzed the results of 32 trials that included more than 9,600 women. After their analysis, the researchers came to several conclusions that could help decide how long to take antibiotics.

The first conclusion: three days of treatment is usually enough to relieve symptoms in women with uncomplicated UTIs. Taking antibiotics for longer does not improve symptom relief, but it does lead to more adverse effects, such as stomach and bowel problems or skin rashes.

Another difference was found when the urine of the women was tested. When someone has a UTI, bacteria can be detected in their urine. After three-day antibiotic treatment, bacteria could still be found in some women's urine. After five days, though, the urine was bacteria-free in almost all the women.

Whether these leftover bacteria cause any health problems is not really known. The trials did not allow any clear conclusions about whether an infection is more likely to come back if only a short course of antibiotics is taken. The length of therapy depends on what is considered to be more important: preventing the UTI coming back or avoiding adverse effects. Women who want to be as sure as possible that the infection is completely gone might choose to take the drugs for five or more days. For women who would rather only take antibiotics for a short amount of time because they want to avoid adverse effects, a three-day course would be an option.

We are currently working on further information about the prevention and treatment of urinary tract infections. As soon as it is published on our website, we will include a link to it here. If you would like to be informed when we publish new information, you can subscribe to our newsletter.

Author: German Institute for Quality and Efficiency in Health Care (IQWiG)

© IQWiG (Institute for Quality and Efficiency in Health Care)