Urinary tract infections (UTIs) explained

Understand what causes a UTI and what your treatment options are.


What is a urinary tract infection?

A urinary tract infection (UTI) is an infection of the urinary system. The urinary system consists of the kidneys, the ureters, the bladder and the urethra.

When an infection affects the lower urinary tract (urethra or bladder), it may be called urethritis, or cystitis if it affects the bladder. When it affects the upper urinary tract (ureters or kidneys) it is called ureteritis, or pyelonephritis if it affects the kidneys.

What causes UTIs?

Most UTIs are caused by the spread of bacteria (eg, Escherichia coli) from digestive system — where they usually live and do not cause a problem — to the urethra (often via the anus). Once inside the urinary tract, these bacteria can multiply and cause an infection resulting in local irritation and inflammation.

For most people, a UTI is a one-off illness that resolves quickly and responds to treatment with antibiotics when necessary. However, for some people, UTIs are a recurrent (recurring) problem.

You are considered to have recurrent UTIs if you have either:

  • 2 or more UTIs within 6 months, or
  • 3 or more UTIs within 1 year.

How are urinary tract infections diagnosed?

To diagnose a UTI, your healthcare professional will ask you about your symptoms, perform a physical examination, and will ask you for a urine sample for testing.

You will be asked to provide a mid-stream urine (MSU) sample. A sample that is collected 'mid-stream' is important in order to stop bacteria present around the urethra, the vagina, the anus, the groin area and on your hands from contaminating the urine test.

Urine testing

A formal urine test is a series of tests called a urine M/C/S (microscopy, culture and sensitivity/susceptibility). 

The first test, called a microurine or urine microscopy, checks for the presence of any blood or pus. This is generally followed by a urine culture test to detect the type and number of bacteria in the urine. How sensitive the bacteria is to certain antibiotics may also be tested at this stage, and these results help your healthcare professional to decide on the most appropriate antibiotic treatment.

Antibiotics for urinary tract infections

There are several different types of antibiotics that can be used, if needed, to treat urinary tract infections. Your prescriber will decide on the most appropriate antibiotic for you, depending on what infection you have (eg, cystitis, pyelonephritis) and the type of bacteria causing it.

Using antibiotics can contribute to the problem of antibiotic resistance. Find out more about what antibiotic resistance is and what you can do to prevent it.

If you are given antibiotic treatment for a UTI and your symptoms don’t improve at all or improve only slightly, it could be a sign that the infection is due to an antibiotic-resistant bacteria.

Relieving UTI symptoms

While you are taking antibiotics to treat a UTI, it is recommended that you drink plenty of water and make sure you completely empty your bladder each time you go to the toilet.

Depending on the kind of antibiotic treatment prescribed, your healthcare professional may recommend the use of urinary alkalylinisers which make the urine less acidic and can ease the pain and burning sensation during urination that sometimes occurs with UTIs.

Any abdominal, pelvic, or back pain due to an upper UTI can usually be managed with over-the-counter (OTC) pain relief, such as paracetamol, ibuprofen or naproxen.

Complications of urinary tract infections

For most people, urinary tract infections are not serious. However, the symptoms can cover a wide range — from mild to severe. For some people, a UTI can have serious complications, such as kidney damage, kidney failure, or sepsis (blood poisoning).

When to seek medical advice

You are at greater risk of developing complications from a UTI and should seek medical advice  promptly if you:

  • have existing kidney disease, diabetes, or another chronic condition
  • are pregnant
  • are over the age of 65
  • or have one or more of the following symptoms - high temperature (38°C or above), shivering, nausea and/or vomiting, diarrhoea or worsening pain in your abdomen, pelvis or back.

Children and babies and urinary tract infections

See your doctor promptly if you think your child or baby has a UTI (or another infection). Although UTI in children can usually be treated quickly and effectively, serious complications can occur if left untreated. This includes scarring of the kidneys, which may cause kidney disease and high blood pressure (hypertension).

Active ingredients of antibiotics for urinary tract infections

There are several different types of antibiotics that can be used, if they are needed, to treat urinary tract infections. The best antibiotic for your infection will depend on the type of infection you have and what bacteria are causing it.

Antibiotics used to treat urinary tract infections (UTIs)

May be prescribed for:Active ingredientBrand name (examples)
Women (who are not pregnant)amoxicillin+clavulanate
Alprim, Amoxyclav, Augmentin Duo, Cephalexin, Ibilex, Keflex, Triprim
Pregnant womenamoxicillin+clavulanate
Cephalexin, Ibilex, Keflex
Cephalexin, Ibilex, Triprim

Mild UTI

Severe UTI

Alprim, Cephalexin, Ibilex, Keflex, Triprim

For some high-risk individuals (eg, a person who has a urinary catheter or someone who has undergone urological surgery), a UTI may be caused by a fungus called Candida, rather than by bacteria. In this instance, a health care professional may prescribe an antifungal medicine to treat the infection, and not antibiotics.

What are the side effects of antibiotics?

Like all medicines, antibiotics that you may be taking for a urinary tract infection have the potential to cause side effects. Ask your prescriber or pharmacist about the possible side effects of your medicine. You should also ask if there are any medicines you should not take with your antibiotic.

For more information, see the Consumer Medicine Information (CMI) for your brand of medicine, available on our Medicine Finder page or from your pharmacist or prescriber.

Can UTIs be prevented?

For some people, a UTI is a one-off occurrence that resolves quickly and responds to treatment. However, for some people, UTIs can become a recurrent problem, becoming more difficult to manage and treat over time. There is no one particular cause for recurrent UTIs, but certain factors increase the risk of infection and re-infection in some people, such as:

  • sexual activity (including anal sex)
  • condoms or diaphragms containing spermicide
  • hormonal deficiency (in women after menopause)
  • diabetes or immunosuppression
  • kidney stones
  • incontinence and/or weakened pelvic floor (pelvic organ prolapse)
  • inflammation of the prostate in older men (eg, prostatits, benign prostatic hyperplasia)
  • underlying abnormalities of the urinary tract (eg, vesico-ureteral reflux)

Medicines to help with prevention

If you have recurrent UTIs and your prescriber has ruled out any underlying disease or abnormality of the urinary tract as a cause, you may be prescribed preventive antibiotics. This is not a recommended course of action in everyone and your prescriber will need to consider your particular circumstances. 

Use of other treatments such as intravaginal oestrogen therapy for postmenopausal women, or cranberry supplements have been examined in trials. Research has reported that intravaginal oestrogen therapy (pessaries or creams) relieves UTI symptoms and reduces the number of recurrent infections. However,  findings are unclear about whether the type of therapy and the length of treatment have any effect on UTI recurrence. Evidence to support use of cranberry products remains unclear - likely due to the many different products that have been tested, and the many different populations that have been involved in the studies. People taking warfarin should not take cranberry supplements or drink cranberry juice.

There is some evidence that taking methamine hippurate  tablets may be helpful in preventing recurrent UTIs in some people. This medicine works by changing the chemical composition of your urine, making it ’less attractive’ to bacteria, and can be used as an alternative for preventing recurrent UTIs in people who can’t take antibiotics. Because it isn’t an antibiotic, it may be a helpful tool for preventing antibiotic resistance. However, methenamine hippurate is not as effective as antibiotics for preventing recurrent UTI, and more research is required to show the true protective benefit of this medicine.