Urethritis, inflammation of the tube that carries urine out of the body, is most commonly caused by sexually transmitted infections. Unprotected vaginal, oral, or anal sex is the primary way bacteria or viruses reach the urethra, though non-infectious triggers like irritation or injury can also cause it. The condition affects both men and women, and many cases produce no symptoms at all.
Sexually Transmitted Infections Are the Leading Cause
The two bacteria responsible for most cases of urethritis are gonorrhea and chlamydia. These are passed between partners during vaginal, oral, or anal intercourse. Gonorrhea infection of the urethra is frequently accompanied by chlamydia at the same time, which is why testing and treatment often cover both. The World Health Organization estimated 82 million new gonorrhea infections and 129 million new chlamydia infections globally in 2020 alone, with more than 1 million curable STIs acquired every day worldwide among people aged 15 to 49.
When urethritis isn’t caused by gonorrhea, it’s classified as nongonococcal urethritis (NGU). Chlamydia accounts for 15% to 40% of those cases, with younger people making up a larger share. Another bacterium called Mycoplasma genitalium has emerged as a significant cause, responsible for roughly 15% to 20% of NGU cases overall and up to 40% of cases where urethritis keeps coming back after treatment. Trichomoniasis, a parasitic infection also spread through sex, can cause urethritis as well, and herpes simplex virus is an occasional contributor.
How Infection Reaches the Urethra
During sexual contact, bacteria or viruses from an infected partner’s genitals, mouth, or rectum come into direct contact with the urethral opening. In men, the opening is at the tip of the penis. In women, it sits just above the vaginal opening. Either way, pathogens can enter and colonize the urethral lining, triggering inflammation.
You don’t need to have symptoms yourself, or for your partner to have visible symptoms, for transmission to happen. The majority of STIs are asymptomatic, meaning the infection is present and contagious without any obvious signs. This is one reason urethritis spreads so easily. Someone can carry chlamydia or gonorrhea for weeks or months, passing it to partners without knowing.
Non-Sexual Causes
While STIs dominate the picture, urethritis can develop without sexual contact. Urinary tract infections, where bacteria from the digestive tract migrate to the urethra, are one non-sexual cause. This is more common in women because of the shorter distance between the urethra and rectum. Catheter insertion or other medical instruments that pass through the urethra can introduce bacteria or physically irritate the tissue. Chemical irritation from soaps, spermicides, or antiseptics that contact the genital area can inflame the urethra as well. These non-infectious cases tend to resolve once the irritant is removed, but they can mimic the symptoms of an STI closely enough that testing is still important.
How Quickly Symptoms Appear
The timeline between exposure and symptoms depends on the pathogen involved. Gonorrhea moves fast, with symptoms typically showing up within 2 to 3 days of exposure. Chlamydia is slower and quieter, often taking 1 to 3 weeks to produce noticeable symptoms, and many chlamydia infections never cause symptoms at all. Mycoplasma genitalium follows a similar delayed pattern.
When symptoms do develop, they usually include a burning sensation during urination, discharge from the urethra (which can range from clear to yellowish or greenish), and an itching or irritated feeling at the urethral opening. In men, these signs are often more obvious. In women, urethritis symptoms frequently overlap with bladder infections or vaginal infections, making it harder to identify without testing.
Who Is at Higher Risk
Several factors increase the likelihood of developing urethritis. Having unprotected sex, meaning vaginal, anal, or oral sex without a condom or dental dam, is the most significant one. Having multiple sexual partners raises cumulative exposure. A prior history of STIs also increases risk, both because of reinfection from untreated partners and because certain infections can make the urethra more vulnerable to new ones.
Age plays a role too. Younger adults, particularly those under 25, account for a disproportionate share of chlamydia and gonorrhea cases. Men who have sex with men face elevated rates of both gonococcal and nongonococcal urethritis. And anyone whose partner has recently been diagnosed with an STI should assume they’ve been exposed, even without symptoms.
How Urethritis Is Diagnosed
Diagnosis starts with a urine sample. Nucleic acid amplification tests (NAATs) are the preferred method for detecting gonorrhea and chlamydia, and for men, a urine sample is all that’s needed. These tests are highly accurate and can identify infection even when no symptoms are present. In some cases, a clinician may also take a swab of urethral discharge and examine it under a microscope. Certain bacterial shapes visible on the slide point directly to gonorrhea, while their absence in the presence of inflammation suggests nongonococcal urethritis.
Because gonorrhea and chlamydia so often occur together, testing typically covers both regardless of which one is suspected. If initial treatment doesn’t resolve symptoms, testing for Mycoplasma genitalium may follow, since this pathogen requires different antibiotics and is increasingly resistant to standard treatments.
Reducing Your Risk
Consistent condom use during vaginal, anal, and oral sex is the most effective way to prevent the STIs that cause urethritis. Barrier methods don’t eliminate risk entirely, but they dramatically reduce it. Reducing the number of sexual partners lowers cumulative exposure. Regular STI screening, especially if you’re under 25 or have new or multiple partners, catches asymptomatic infections before they spread. If you’re diagnosed, your recent sexual partners need to be notified and tested, because reinfection from an untreated partner is common and restarts the cycle.
For non-infectious urethritis, avoiding harsh soaps, fragranced products, and spermicides near the genital area can prevent chemical irritation. Staying hydrated and urinating after sex helps flush bacteria from the urethra before they can establish an infection.