Two different bacterial infections, both sexually transmitted, frequently confused because they cause similar symptoms and often occur together. Chlamydia is caused by Chlamydia trachomatis, gonorrhoea by Neisseria gonorrhoeae. Both are commonly symptomless, which is why testing rather than symptoms is what identifies them.
The core difference
- chlamydia — infection with the bacterium Chlamydia trachomatis.
- gonorrhoea — infection with Neisseria gonorrhoeae.
Different organisms, overlapping presentation, different antibiotic sensitivities — which is why they are tested for separately even though a single sample often covers both.
Why they are confused
Three reasons: the symptoms overlap almost completely, co-infection is common, and both are frequently asymptomatic. A large share of cases in both cause no noticeable symptoms at all, so neither can be ruled out by feeling well.
Antibiotic resistance is the live issue
Gonorrhoea has developed resistance to successive classes of antibiotic over decades, and the World Health Organization has repeatedly flagged it as a priority pathogen. Treatment guidance changes as resistance shifts, which is precisely why self-treatment with leftover antibiotics is a bad idea — the recommended agent has changed several times.
Chlamydia has so far remained more consistently treatable.
The names
Chlamydia is from Greek chlamys, a short cloak — describing how the bacterium appears to drape around the host cell nucleus under a microscope.
Gonorrhoea is from Greek gonos (seed) and rhoia (flow), a second-century description by Galen based on the mistaken belief that the discharge was semen. The name preserves an error nearly two thousand years old.
The old slang the clap is of uncertain origin — possibly from Old French clapier, a rabbit warren and by extension a brothel.
Spelling
Gonorrhoea is the British spelling, gonorrhea the American, following the same pattern as diarrhoea and oesophagus.
This page explains the words, not your health. Testing and treatment are matters for a clinic or doctor.
Frequently asked questions
What is the difference between chlamydia and gonorrhoea?
They are caused by different bacteria — Chlamydia trachomatis and Neisseria gonorrhoeae. Symptoms overlap heavily and co-infection is common, so they are tested for separately.
Can you have either without symptoms?
Yes. A large proportion of cases of both cause no noticeable symptoms, which is why testing rather than symptoms is what identifies them.
Why is antibiotic resistance mentioned with gonorrhoea?
It has developed resistance to successive antibiotic classes, and treatment guidance has changed several times as a result.