Chlamydia itself is not life threatening in the vast majority of cases. It’s a bacterial infection that is fully curable with a short course of antibiotics, and most people recover without lasting effects when treated promptly. The real danger comes from leaving it untreated, sometimes for months or years without knowing you have it, which can trigger complications that do carry serious and occasionally life-threatening risks.
Why Untreated Chlamydia Becomes Dangerous
Chlamydia is often called a “silent” infection because it frequently causes no symptoms at all. Without testing, many people carry it for long stretches without realizing anything is wrong. During that time, the bacteria can spread deeper into the reproductive tract and, in rare cases, beyond it.
The most significant risk for women is pelvic inflammatory disease (PID), an infection of the uterus, fallopian tubes, or ovaries. PID can develop when chlamydia travels upward from the cervix. If PID is not diagnosed and treated in time, it can cause sepsis, septic shock, and death. That outcome is uncommon with access to modern healthcare, but it is a real pathway from an otherwise “mild” STI to a medical emergency.
Ectopic Pregnancy and Infertility
One of the most dangerous downstream effects of untreated chlamydia in women is ectopic pregnancy, where a fertilized egg implants outside the uterus, usually in a fallopian tube. A ruptured ectopic pregnancy causes internal bleeding and is a life-threatening emergency requiring immediate surgery. Women who have tested positive for chlamydia face a 30 to 90 percent increased risk of ectopic pregnancy and tubal factor infertility compared to women who have not had the infection.
The scarring that causes these problems builds silently. Chlamydia inflames the lining of the fallopian tubes, and as the body heals, scar tissue forms. That scar tissue can partially or fully block the tubes, making it harder for an egg to travel normally. By the time a woman discovers she has blocked tubes, often while trying to get pregnant, the damage is already done.
Risks During Pregnancy and for Newborns
Chlamydia during pregnancy increases the risk of preterm labor by about 35 percent and nearly doubles the risk of perinatal death, based on a meta-analysis published in The Brazilian Journal of Infectious Diseases. Low birth weight risk also rises by roughly 50 percent. These are not abstract statistics. Premature birth is a leading cause of infant death worldwide, and chlamydia is a preventable contributor.
A baby born through an infected birth canal can pick up the bacteria directly. This can cause eye infections (neonatal conjunctivitis), ear infections, and a type of pneumonia that typically appears between one and three months of age. Chlamydia pneumonia in infants tends to be mild, with coughing and nasal congestion but usually no fever, though it still requires treatment. The more serious threat is the cascade of prematurity-related complications that chlamydia can set in motion before the baby is even born.
Complications in Men
For men, untreated chlamydia most commonly causes epididymitis, a painful inflammation of the tube behind the testicle that carries sperm. This is uncomfortable and can lead to chronic pain or reduced fertility if left untreated, but it is rarely life threatening on its own. In severe cases with high fever or abscess formation, hospitalization may be necessary. The CDC notes that diabetes, older age, and elevated inflammatory markers can indicate more serious disease requiring closer monitoring.
Men are unlikely to die from chlamydia complications directly. The larger concern is transmission to partners who may face the more dangerous outcomes described above, along with the fact that having an active STI like chlamydia can amplify the risk of acquiring HIV by as much as eight times.
A Less Known Complication: Liver Capsule Inflammation
Chlamydia can occasionally cause a condition called Fitz-Hugh-Curtis syndrome, where PID-related inflammation spreads to the tissue surrounding the liver. This produces sharp pain in the upper right side of the abdomen that can mimic gallbladder disease, liver problems, or even a heart attack. Sticky, string-like adhesions form between the liver capsule and the abdominal wall or diaphragm. It’s treatable with antibiotics, but it’s a striking example of how far chlamydia’s effects can reach when the initial infection goes unmanaged.
Treatment Is Simple and Effective
When caught, chlamydia is one of the easiest STIs to treat. A seven-day course of the antibiotic doxycycline is the current first-line recommendation. In a clinical trial focused on rectal chlamydia, doxycycline achieved a 100 percent cure rate. A single-dose alternative exists but is less effective, particularly for rectal infections, where it cured only about 74 percent of cases.
After treatment, retesting about three months later is recommended because reinfection is common, especially if a sexual partner was not treated at the same time. For pregnant women, a follow-up test four weeks after treatment confirms the infection has cleared.
Who Should Be Tested
Because chlamydia so often has no symptoms, screening is the main line of defense against its complications. Current CDC guidelines recommend annual screening for all sexually active women under 25, and for older women with risk factors like new or multiple partners. Pregnant women under 25 should be tested early in pregnancy and again in the third trimester.
Men who have sex with men should be screened at least annually at all sites of sexual contact, with more frequent testing (every three to six months) for those on HIV prevention medication, living with HIV, or who have multiple partners. For heterosexual men at low risk, routine screening isn’t strongly recommended, though it may be offered in high-prevalence settings like STI clinics or correctional facilities. Transgender and gender diverse individuals should follow screening guidelines based on their anatomy and sexual practices.
The gap between how easy chlamydia is to treat and how serious its complications can become makes screening the single most important thing you can do. The infection itself won’t kill you. But the problems it causes when no one catches it in time can put your fertility, your pregnancy, or in rare cases your life at genuine risk.