Gonorrhea and chlamydia spread through sexual contact, primarily during vaginal, anal, or oral sex. Both infections are caused by bacteria that pass from one person to another through infected bodily fluids and direct contact with infected mucous membranes. The majority of people who carry these infections have no symptoms at all, which is the single biggest reason they continue to spread.
Sexual Contact Is the Primary Route
Both gonorrhea and chlamydia are transmitted when bacteria from an infected person’s genitals, rectum, or throat come into contact with another person’s mucous membranes during sex. Vaginal and anal intercourse are the most efficient routes, but oral sex transmits both infections as well. Any sexual contact involving the penis, vagina, mouth, or anus can potentially pass the bacteria, even without ejaculation.
These bacteria are fragile organisms that thrive in warm, moist environments like the urethra, cervix, rectum, and throat. They don’t survive well outside the body. Chlamydia bacteria die on plastic surfaces within 30 minutes to 2 hours. Gonorrhea bacteria can persist on surfaces slightly longer, but the realistic risk of catching either infection from a toilet seat, towel, or shared object is extremely low. Direct person-to-person contact during sex is how these infections actually spread.
Infections in the Throat and Rectum
Gonorrhea and chlamydia aren’t limited to the genitals. Oral sex can transmit both bacteria to and from the throat, and anal sex can infect the rectum. Research on gonorrhea transmission has identified additional pathways: kissing may transmit gonorrhea from one throat to another, and oral-anal contact can spread the bacteria between the throat and rectum. These findings, published by the CDC, help explain why gonorrhea remains difficult to control even among people who use condoms for penetrative sex but not during oral contact.
Throat and rectal infections are especially likely to go unnoticed because they rarely cause obvious symptoms. Standard STI testing that only checks a urine sample will miss them entirely. If you’ve had oral or anal sex, those sites need to be tested separately with a swab.
Most Infected People Have No Symptoms
This is the fact that changes how you should think about transmission risk. An estimated 77% of all chlamydia cases and 45% of all gonorrhea cases never produce symptoms. The infected person feels completely fine, has no idea they’re carrying the bacteria, and continues having sex. Among untreated infections, 95% of chlamydia cases and 86% of gonorrhea cases went untreated specifically because the person never experienced anything that would prompt a doctor visit.
When symptoms do appear, gonorrhea tends to show up within 2 to 10 days of exposure, though it can take up to 30 days. Chlamydia symptoms typically emerge 7 to 21 days after exposure. For gonorrhea, symptoms often include painful urination and discharge. Chlamydia symptoms are generally milder, which partly explains why it goes undetected even more often. But the absence of symptoms doesn’t mean the infection is harmless or not contagious. You can transmit either infection the entire time you’re carrying it, whether you feel anything or not.
Women Face Higher Biological Risk
Women are significantly more affected by both infections than men, and anatomy is a major reason. The cervix is lined with cells that are particularly vulnerable to both chlamydia and gonorrhea bacteria, creating a larger target for infection during vaginal sex. In 2024, roughly 944,000 chlamydia cases were reported in women compared to about 564,000 in men. The difference isn’t just about who gets tested more often. The physical structure of the female reproductive tract makes transmission from an infected male partner to a female partner more efficient than the reverse.
This biological vulnerability also means untreated infections carry steeper consequences for women, including pelvic inflammatory disease, chronic pain, and fertility problems.
Transmission During Childbirth
A pregnant person carrying gonorrhea or chlamydia can pass the bacteria to their baby during vaginal delivery as the baby moves through the birth canal. The most common result is an eye infection in the newborn, which is why hospitals routinely apply antibiotic ointment to newborns’ eyes shortly after birth. In more serious cases, chlamydia passed during delivery can cause pneumonia in the infant. This is one reason prenatal care includes routine STI screening.
Reinfection After Treatment
Curing gonorrhea or chlamydia with antibiotics does not give you any immunity. You can catch the exact same infection again the next time you’re exposed. Reinfection rates are substantial: studies show about 11% of men treated for chlamydia and 7% treated for gonorrhea become reinfected, often within months. The most common reason is an untreated sexual partner passing the bacteria right back.
This cycle is why partner treatment matters so much. When only one person in a sexual partnership gets treated, the untreated partner acts as a reservoir, reinfecting the treated person as soon as they resume sexual contact. Some healthcare providers offer expedited partner therapy, giving you medication to bring directly to your partner so they can be treated without a separate appointment. Even with partner treatment, reinfection still occurs in a meaningful percentage of cases, which is why retesting 3 months after treatment is recommended.
How Common These Infections Are
Over 2 million cases of chlamydia, gonorrhea, and syphilis combined were reported in the United States in 2024. Chlamydia alone accounted for roughly 1.5 million of those, making it the most commonly reported bacterial STI in the country. Gonorrhea added another 543,000 cases. Both infections have been declining for the past few years (chlamydia down 8% and gonorrhea down 10% from 2023), but overall case counts remain 13% higher than they were a decade ago. These numbers also only reflect cases that were actually diagnosed and reported. Given how often both infections produce no symptoms, the true number of people infected at any given time is considerably higher.