Most UTIs affect the lower portion of the urinary tract, including the bladder, urethra, or prostate. If left untreated, a lower UTI can progress to the upper urinary tract, which may involve the ureters and kidneys.

Although lower and upper UTIs are caused by infectious bacteria that enter various regions of the urinary tract, the two conditions have some key differences.

For example, lower UTIs typically cause discomfort during or after urination. Upper UTIs typically cause flu-like symptoms that affect the whole body.

The medical urgency of the two infections is also different.

According to Aleece Fosnight, a board certified physician assistant and medical adviser at Aeroflow Urology, upper UTIs are more serious than lower UTIs.

“Upper UTIs impact the kidneys,” explains Fosnight. Your kidneys are responsible for filtering harmful toxins out of your bloodstream.

If your kidneys are infected and unable to function properly, bacteria may be able to enter the bloodstream. The introduction of bacteria into the bloodstream can cause sepsis and other severe complications.

Lower UTIs typically cause symptoms such as:

Upper UTIs typically cause symptoms such as:

Youth healthcare professional and medical adviser at Flo Health, Netherlands, Andrea Maduro, MD, explains that UTIs generally occur when bacteria get into the urinary tract.

The urinary tract includes the following:

  • urethra, a tube that carries urine from the bladder to outside the body
  • bladder
  • ureters, the two tubes that carry urine from the kidneys to the bladder
  • kidneys

Bacteria may enter the urethra when wiping after using the bathroom or during partnered sexual activity, but it isn’t always clear why UTIs develop.

A lower UTI occurs when bacteria travel as high as the urethra or bladder. An upper UTI occurs when bacteria travel beyond this point and into the ureters or kidneys.

Your anatomy plays an important role in predicting your overall risk of a UTI.

The urethral opening is usually located at the tip of the penis or just below the glans clitoris. The closer the urethral opening is to the anus, the easier it is for bacteria around the anus to enter the urethra.

Maduro explains that the overall urethral structure is also shorter in people who have a vulva, which means the bacteria can more easily enter other portions of the urinary tract.

If you have a vulva, you may also be more likely to develop a UTI if you:

The following factors can increase the risk of UTIs in people of all anatomies:

Maduro explains that, if you have a history of UTIs or have typical UTI symptoms, a healthcare professional may be able to make a diagnosis based on your symptoms alone.

Some clinicians prefer to take a urine sample for testing. People who have never experienced a UTI or have atypical symptoms are usually advised to undergo a urinalysis or urine culture.

A urinalysis may be used to check for red or white blood cells, which could indicate an underlying infection. A urine culture can be used to identify the specific bacteria present.

All UTIs are treated with antibiotics, but, according to Maduro, the severity and location of the infection will specify the following:

  • medication prescribed
  • route of administration
  • length of treatment

Simple or “uncomplicated” UTIs are usually treated with a 3–5 day course of oral antibiotics. Chronic, recurrent, or otherwise “complicated” UTIs may involve a longer course of oral antibiotics or intramuscular or intravenous antibiotics.

UTIs in the lower urinary tract can go on to affect the upper urinary tract if left untreated. Upper UTIs have an increased likelihood of complications, such as:

UTIs that are left untreated during pregnancy can increase the risk of:

According to Maduro, the following can help reduce your risk of UTIs:

In some situations, drinking cranberry juice and taking a supplement called D-mannose may also help prevent UTIs.

Consult with a healthcare professional before adding a new supplement to your routine, especially if you have diabetes.

Lower UTIs are common. Prompt diagnosis and treatment can help reduce the likelihood of complications, particularly when it comes to upper UTIs or UTIs that occur during pregnancy.

Consult with a healthcare professional if you’re experiencing unusual symptoms or suspect you have a UTI. You may also find it helpful to take an at-home test so you can share your results with a clinician.

Gabrielle Kassel (she/her) is a queer sex educator and wellness journalist who is committed to helping people feel the best they can in their bodies. In addition to Healthline, her work has appeared in publications such as Shape, Cosmopolitan, Well+Good, Health, Self, Women’s Health, Greatist, and more! In her free time, Gabrielle can be found coaching CrossFit, reviewing pleasure products, hiking with her border collie, or recording episodes of the podcast she co-hosts called Bad In Bed. Follow her on Instagram @Gabriellekassel.