Gonorrhea and syphilis are both curable bacterial STIs, but they behave differently: gonorrhea is the classic "discharge" infection — burning urination and penile or vaginal discharge — while syphilis announces itself first as a painless sore, then a body rash. You usually can't tell them apart by symptoms, so a test is what settles it, and the treatments are completely different antibiotics.
Neisseria gonorrhoeae
Treponema pallidum
| Item | Value |
|---|---|
| Gonorrhea | curable — Neisseria gonorrhoeae |
| Syphilis | curable — Treponema pallidum |
What each infection is
Gonorrhea
Gonorrhea is caused by the bacterium Neisseria gonorrhoeae, which can infect the genitals, the rectum, and the throat CDC. It spreads through vaginal, anal, and oral sex, and a single exposure to an infected partner is enough. Because it can colonize the throat and rectum without symptoms, many infections carry on undetected and get passed along. For the full picture of transmission, complications, and screening, see our overview of gonorrhea.
Syphilis
Syphilis is caused by a different bacterium, Treponema pallidum, and it's curable with the right antibiotics CDC. Syphilis moves through stages over weeks to months, each with its own signs, and it can quietly progress if untreated. We walk through every stage in what is syphilis? causes, stages & risks.
Symptoms compared
The two infections produce different signatures when symptoms show up at all. Gonorrhea irritates the urethra and mucous membranes; syphilis leaves a sore and later a rash.
With gonorrhea, men typically notice burning when urinating and a white, yellow, or green penile discharge; less commonly, the testicles become swollen and painful. In women, most have no symptoms at all, and when symptoms do appear they're easy to miss: painful or burning urination, increased vaginal discharge, and bleeding between periods.
Syphilis starts in its primary stage with one or more painless, firm, round sores called chancres at the exact site where the bacterium entered — the penis, vagina, anus, rectum, lips, or mouth. A chancre lasts a few weeks and then heals on its own whether or not you treat it, which fools people into thinking the problem is gone. Weeks later, secondary syphilis can bring a rough red or reddish-brown rash that may appear on the palms and soles, an unusual spot that's a real clue, along with mucous-membrane lesions, fever, swollen lymph nodes, sore throat, patchy hair loss, headache, weight loss, muscle aches, and fatigue.
How to tell them apart
A few discriminating features help a clinician sort these out:
- Discharge vs. sore: Gonorrhea's hallmark is discharge and burning urination. Syphilis shows up as a painless ulcer, then a rash, with no discharge.
- Pain: The syphilis chancre is classically painless, which is why people overlook it. Gonorrhea's urethritis hurts when you urinate.
- Where it shows: A rash on the palms and soles points toward secondary syphilis; isolated burning and discharge point toward gonorrhea.
- Timing: Gonorrhea symptoms tend to come on within days of exposure. Syphilis unfolds in stages over weeks to months, and a healing sore can be followed by a body-wide rash later.
In real life the symptoms overlap, and so many infections are silent, that you can't reliably tell these apart by feel. A test is what settles it.
Syphilis vs gonorrhea: side-by-side
| Gonorrhea | Syphilis | |
|---|---|---|
| Cause | Neisseria gonorrhoeae | Treponema pallidum |
| Classic sign | Burning urination, penile/vaginal discharge | Painless sore (chancre), then rash on palms/soles |
| Painful? | Yes — burning with urination | The early sore is painless |
| Course | Symptoms within days; often silent in women | Progresses through stages over weeks to months |
| Test | NAAT (urine or swab) | Two blood tests: nontreponemal + treponemal |
| First-line treatment | A single ceftriaxone injection | A benzathine penicillin G injection |
Testing
The two infections are diagnosed in completely different ways, so a clinician orders specific tests rather than guessing from symptoms. Gonorrhea is detected with a nucleic acid amplification test (NAAT), the preferred and required screening method, with sensitivity usually above 90% and specificity around 99% CDC. In practice that means a urine sample or a self-collected swab — vaginal, rectal, or throat depending on exposure.
Syphilis isn't found on that swab; it requires blood work, and a diagnosis takes two serologic tests. You need a nontreponemal test (RPR or VDRL) plus a treponemal test (TP-PA, FTA-ABS, EIA, or CIA) CDC, 2024. The two-test design exists because either one alone can mislead — a single positive can be a false alarm, so the pair confirms each other.
Testing is faster and cheaper than most people expect: a urine cup, a quick self-swab, or a blood draw depending on what's suspected, and it's free or low-cost at health departments, Planned Parenthood, and Title X clinics. Both infections have a window before they reliably show up, so check when to test after exposure before you book, and you can get tested for both at once.
Treatment compared
Gonorrhea is now treated with a single intramuscular injection of ceftriaxone — 500 mg for people under 150 kg, or 1 g for those 150 kg or more — which covers urogenital, rectal, and throat infection in one shot CDC. Azithromycin used to be paired with it but was dropped because resistance climbed fast: isolates with elevated azithromycin MICs rose from 0.6% in 2013 to 4.6% in 2018, leaving ceftriaxone alone as first-line Clin Infect Dis, 2020. Throat gonorrhea is harder to clear than genital infection — even fully susceptible pharyngeal infections failed ceftriaxone about 4.6% of the time — so a test-of-cure 7–14 days later is advised for the throat.
Syphilis is treated with penicillin, which remains the only reliable cure. Primary, secondary, and early latent syphilis call for benzathine penicillin G 2.4 million units IM in a single dose; late or unknown-duration disease needs three weekly injections instead CDC. The correct product is benzathine penicillin G (Bicillin L-A). The combination product Bicillin C-R (benzathine plus procaine) is not an acceptable substitute and has caused treatment-failure errors. No oral drug dependably replaces these injections CDC.
One expected reaction can scare people: within a couple of hours of the first penicillin injection, some get fever, chills, and headache. That's the Jarisch-Herxheimer reaction — dying bacteria releasing inflammatory signals, not a penicillin allergy. It affects roughly 95% of people treated for secondary syphilis and settles within about 24 hours StatPearls.
Can you have more than one at once?
Yes — co-infection is common, because both spread through the same sexual contact and share risk factors. A genital sore from syphilis can even raise the chance of acquiring or transmitting other infections during the same encounter. Clinicians test for a panel rather than chasing a single symptom, and a positive result on one should prompt screening for the others.
When to see a clinician
Get evaluated if you notice any sore, rash, unusual discharge, burning with urination, or pelvic or testicular pain — or if a partner tests positive, even when you feel fine. Both infections are climbing or shifting in ways that matter: reported gonorrhea has been falling, with about 601,000 cases in 2023 (180 per 100,000), down from a 2021 peak of 214 per 100,000, while syphilis keeps rising — about 53,000 primary-and-secondary cases in 2023, and the late or unknown-duration stage jumped from 14 to nearly 30 per 100,000 between 2020 and 2023 CDC AtlasPlus, 2023. Catching either one early makes treatment simpler and prevents the serious complications of untreated disease.