NGU, or non-gonococcal urethritis, is an infection of the urethra (the tube that carries urine out of the body) caused by something other than gonorrhea. It’s one of the most common sexually transmitted infections, particularly in men, and is usually caused by chlamydia or a handful of other bacteria passed during sex. Most cases clear up with a course of antibiotics, but untreated NGU can lead to serious reproductive complications.
What NGU Feels Like
The hallmark symptoms are discharge from the penis, a burning sensation when urinating, and itching or irritation at the tip of the urethra. The discharge is often white or cloudy and tends to be lighter than what you’d see with gonorrhea, which typically produces thicker, yellow-green discharge. Some people notice symptoms only in the morning before their first urination.
Not everyone with NGU has obvious symptoms. A significant number of infections are mild enough that they go unnoticed, which is one reason the infection spreads so easily. Symptoms generally appear one to three weeks after exposure, though they can take longer to show up depending on the specific germ involved.
What Causes It
Several different bacteria and organisms can cause NGU. In a study of 155 men diagnosed with the condition, a specific pathogen was identified in 73% of cases, while roughly a quarter had no identifiable cause.
Chlamydia is the leading culprit, found in about 38% of NGU cases. The second most common is Mycoplasma genitalium, showing up in around 23% of cases. A third organism, Ureaplasma urealyticum, accounts for about 18%. Trichomonas vaginalis, a parasite more commonly associated with vaginal infections, is an uncommon cause in men.
The remaining cases with no identifiable pathogen are sometimes called “idiopathic” NGU. These still respond to treatment in many cases, suggesting the cause may be a bacterium that’s simply difficult to detect with standard testing.
How It’s Diagnosed
Diagnosis typically involves two steps: ruling out gonorrhea and confirming that the urethra is actually inflamed. A clinician will take a swab from the urethra or collect a urine sample. Under a microscope, finding five or more white blood cells per high-power field on a stained sample confirms urethritis. A negative gonorrhea test alongside that inflammation points to NGU.
Testing for the specific cause, particularly chlamydia and Mycoplasma genitalium, matters because the right antibiotic depends on which organism is responsible. Nucleic acid amplification tests (a type of highly sensitive lab test) can identify these bacteria from a urine sample, making the process relatively straightforward.
Treatment and Recovery
Most NGU is treated with a short course of antibiotics. Doxycycline, taken twice daily for seven days, is the standard first-line option and works well against chlamydia and many other causes. For people who can’t take doxycycline, a single-dose alternative antibiotic is sometimes used instead.
Mycoplasma genitalium infections can be trickier. Resistance to common antibiotics is a growing problem with this particular bacterium. Research from Taiwan found that roughly 24% of Mycoplasma genitalium samples carried mutations making them resistant to macrolide antibiotics (the class that includes azithromycin), and about 22% showed resistance to fluoroquinolones. When a standard course doesn’t work, your provider may order resistance testing to guide the next choice of antibiotic.
You should avoid all sexual contact for seven days after completing treatment and until symptoms have fully resolved. Even if you start feeling better within the first few days, the infection can still be passed to a partner until that window closes.
What Happens to Sexual Partners
Anyone you’ve had sex with in the 60 days before your diagnosis should be notified and tested. Partners need treatment even if they have no symptoms, because the bacteria responsible for NGU can live silently in the reproductive tract. In women, the same organisms that cause NGU in men often infect the cervix without producing obvious symptoms, creating a cycle of reinfection if only one partner is treated.
Complications of Untreated NGU
Left alone, the infections behind NGU can move deeper into the reproductive system. In men, the most significant risk is epididymitis, an inflammation of the coiled tube behind the testicle where sperm matures. Epididymitis causes pain and swelling in the scrotum and, if it goes untreated long enough, can lead to infertility.
For female partners carrying the same bacteria, the stakes are equally high. Chlamydia and Mycoplasma genitalium can travel upward into the uterus and fallopian tubes, causing pelvic inflammatory disease (PID). A single episode of PID increases the risk of ectopic pregnancy, where a fertilized egg implants outside the uterus. Repeated episodes of PID can cause scarring that leads to chronic pelvic pain and infertility.
Reducing Your Risk
Condoms significantly reduce transmission of the bacteria that cause NGU, though they don’t eliminate risk entirely since some organisms can be present in areas a condom doesn’t cover. Getting tested regularly if you have new or multiple partners catches infections early, often before symptoms appear and before complications develop. If you’re diagnosed, completing the full course of antibiotics, even after symptoms improve, prevents both relapse and the development of antibiotic-resistant bacteria.