What Are the Most Common Causes of Pus in Urine?

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  • Originally Written By: C. Webb
  • Revised By: C. Mitchell
  • Edited By: Daniel Lindley
  • Last Modified Date: 20 July 2018
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Pus in urine is typically caused by a bacterial infection. Urinary tract infections are some of the most common, but inflammation and infection of the kidney can lead to similar results. Pus may also be a sign of a sexually transmitted disease like Chlamydia, or could be caused by a filled abscess on or near the kidney. Pregnant women who notice pus in their urine are usually advised to seek prompt medical care since infections that might otherwise be considered “minor” can be life-threatening to the fetus.

Urinary Tract Infections

Urinary tract infections, commonly abbreviated to “UTIs,” are one of the main causes. In these cases the pus isn’t actually in the urine so to speak, but it appears that way since both substances exit the body together. In most cases the pus builds up in the lining of the urethra, then blends with urine as it as it is forced out. This often causes a slight burning or stinging sensation, and the resulting expulsion tends to have a frothy, cloudy appearance along with a foul or sour smell.


There are a number of reasons people develop UTIs, but they all have to do with bacteria that enters into the urinary tract. Sometimes this is all but inevitable, as is the case when cultures from the bloodstream enter the tract, but in many cases it can be prevented with better hygiene or more intentional self-care. Wearing freshly laundered undergarments, for instance, can help prevent bacteria from entering into the genitals from the outside world, and taking care when wiping and using the restroom can also make a difference. Women are often prone to contracting UTIs after sexual intercourse, too, as fluids and secretions can fairly easily make their way from the sex organs to the urinary opening. Men have some risk in these scenarios, but it isn’t as high.

Stages of Infection

The most basic UTIs occur at the opening of the urethra and are generally considered relatively minor. Medical professionals typically refer to this sort of infection as urethritis. It is sometimes the case that the infection is much more extensive, however, and it can spread through the bladder and up to the kidney where urine is first produced. Infections in the bladder are usually called cystisis; those in the kidney go by the name pyelonephritis.

Sexually Transmitted Diseases

Sexually transmitted diseases (STDs) are another common cause of pus in urine, and can be either bacterial or viral. Chlamydia is one of the most widely diagnosed, but many different diseases, from Herpes to Gonorrhea, can include pus-filled urine as a symptom, usually accompanied by fever and abdominal pain. Pus is usually a byproduct of the body’s immune response as it tries to fight the infection and is almost always a sign that treatment is required. Not all STDs are serious, but few will go away on their own. People who are infected should usually get help as quickly as possible both to rid themselves of the ailment and to prevent the infection from spreading and getting worse.


An abscess is an abnormal growth that can form on almost any internal tissues. They tend to grow in response to specific pressures or stresses, like wounds that never properly healed or injuries that didn’t receive treatment; inflammation and internal swelling can also be to blame. When abscesses happen along the urinary tract, in the bladder, or on the kidney, pus can sometimes leak into or mix in with the urine. The growths are not often dangerous in and of themselves, but once they start leaking a person runs a much higher risk of infection or blood contamination.

Special Concerns During Pregnancy

Medical experts often advise pregnant women to pay special attention to their urine since UTIs and other infections can endanger the life of the fetus. Promptly treating infections can be the difference between a healthy pregnancy and fetal death or defects. Cloudy, pus-like discharge may also be a sign that labor is imminent, though in these cases a thick mucus is often really what is coming out. A certain amount of mucus discharge is usually necessary to clear the cervical opening for the baby to be born.

Common Treatments

Health care providers often start treating both UTIs and STDs with a course of antibiotics to destroy the bacteria and clear up the infection. People receiving this treatment are usually advised to drink plenty of fluids and take special care to keep their genital region clean and dry.

If regular antibiotics don’t seem to be working, more invasive measures may be required. Ultrasounds and other imaging technology can often help detect the presence of abscesses, for instance, and surgery may be needed to remove badly infected tissues or unusually large growths. People can often avoid these outcomes by getting a medical evaluation at the first sign of clouded or otherwise unusual urine.


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Post 2

@Iluviaporos - If one person knows they have a UTI or a similar kind of infection, they should tell their partner.

If they use condoms it will help to prevent transmitting the bacteria like that (although it is still a risk they take).

Eating cranberries is a good way of preventing and treating a UTI. I've heard pineapple and yogurt can also help and of course you should drink lots of water.

However, if you notice the presence of pus in your urine you should get a doctor's opinion rather than rely on home remedies, as it might be something more serious, or quickly become more serious, and you should be on prescribed medication.

Post 1

A really good way of preventing UTIs is to urinate after sex.

Often, simply from the movements people make during sex, bacteria manages to get up into the urethra, and from there to the bladder, where they cause infections. This infection can then be passed back and forth between partners, with each one re-infecting the other unless both are put on medication at the same time.

If you regularly urinate as soon as possible after you have finished sex, it flushes out the bacteria.

Although, unfortunately, some women are so prone to UTIs they get them all the time no matter what they do.

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