Chlamydia and gonorrhoea: what’s the difference?

Of all the STIs, chlamydia and gonorrhoea are the two most common in Australia. They’re easy to confuse because they overlap so much, but there are real differences, including how they’re treated. Knowing them helps you understand when to test and what treatment to expect.

How common are chlamydia and gonorrhoea?

Both are very common STIs, affecting a large number of people in Australia and millions worldwide. People aged 15 to 29 account for most cases. Recent figures show a sharp rise: over three years, chlamydia notifications climbed about 24% and gonorrhoea about 45%. Because neither always causes symptoms, many infections go untreated, which raises the risk of complications later.

What are chlamydia and gonorrhoea?

Both are bacterial infections spread through sexual contact, and it’s common to have both at the same time. That overlap is exactly why testing, rather than guessing from symptoms, is the reliable way to know what you’re dealing with.

What chlamydia and gonorrhoea have in common

How they spread

Both are passed through skin-to-skin contact during vaginal, anal or oral sex, and through sharing sex toys or genital-to-genital contact. They can also be transferred from the genitals to the eyes by the hands, causing eye symptoms.

Symptoms

Both are often symptomless, which drives their spread. When symptoms do appear, the ones common to both include:

• smelly or unusual discharge from the penis, vagina or anus
• burning or discomfort when passing urine
• pain in the lower abdomen, testicles or rectum
• swollen testicles
• pain during sex
• bleeding from the vagina after sex
• redness at the opening of the penis, or conjunctivitis.

After oral sex, either can also cause a sore throat.

Complications

Left untreated, both can cause serious problems. In women, both can lead to pelvic inflammatory disease, which can permanently damage the uterus, fallopian tubes and ovaries, raising the risk of chronic pelvic pain, ectopic pregnancy and infertility. In men, both can damage the reproductive tract and affect fertility. Both can also be passed to a baby around the time of birth.

Treatment and prevention

Both are treated with antibiotics, and having one doesn’t make you immune, so re-infection is always possible. Prevention is the same for both: safer sex with condoms and dental dams for vaginal, anal and oral sex with new or casual partners, not sharing sex toys, and washing them thoroughly after use. And because both are so often symptomless, regular testing is the only reliable way to catch them.

Differences between chlamydia and gonorrhoea

Cause

Chlamydia is caused by Chlamydia trachomatis; gonorrhoea by Neisseria gonorrhoeae. Because they’re different bacteria, they’re treated differently.

Symptoms

Gonorrhoea is more likely to cause rectal symptoms such as itching, soreness or pain when passing a bowel motion. Those symptoms point more towards gonorrhoea than chlamydia.

Complications

Gonorrhoea can be passed to a baby during childbirth, can cause prostate inflammation in men, and, less commonly, can spread to the skin, joints, blood and other organs.

Treatment

Chlamydia is treated with oral antibiotics (at least 7 days). Gonorrhoea usually needs an antibiotic injection plus oral antibiotics, and often stronger or combined therapy because of growing antibiotic resistance. For both, avoid sex for 7 days after starting treatment (or until the course is finished and symptoms have gone, whichever is later). Recent partners should be tested and treated too, going back 6 months for chlamydia and 2 months for gonorrhoea.

At a glance