With Mycoplasma genitalium (Mgen), awareness changes the outcome. Because this bacterium is increasingly resistant to the old single-dose azithromycin, getting it right now means a specific Mgen test, a two-step antibiotic course that starts with doxycycline, and a resistance-guided second drug. Treat partners, finish every pill, and confirm cure when advised.
with the right treatment
testing, not symptoms, decides
| Item | Value |
|---|---|
| Curable? | yes — with the right treatment |
| Tested by | NAAT / lab |
| Often | no symptoms |
| If you may have it | get tested — testing, not symptoms, decides |
How Mycoplasma genitalium is treated
Mgen is stubborn to treat for a structural reason: it lacks a cell wall, so beta-lactam antibiotics like penicillins and cephalosporins have nothing to attack and simply don't work CDC STI Tx Guidelines, 2021. That leaves a narrow set of antibiotics, and the bacterium has been quietly defeating the most-used one. Macrolide-resistance mutations now exceed half of cases in many areas — over 62% in one US STI clinic — so the single azithromycin dose that once cured it frequently fails NYSDOH/Johns Hopkins.
Current care is resistance-guided and two-step, and it always opens with doxycycline to knock the bacterial load down before the second drug finishes the job. The full regimen path depends on what your strain's resistance testing shows:
- If macrolide-sensitive: doxycycline 100 mg twice daily for 7 days, then azithromycin 1 g once, followed by 500 mg daily for 3 days.
- If macrolide-resistant, or if resistance testing isn't available: doxycycline 100 mg twice daily for 7 days, then moxifloxacin 400 mg daily for 7 days.
This is also why a specific Mgen test matters rather than a standard panel. Many tests can now report whether the strain carries macrolide-resistance mutations, and that information decides whether your second drug is azithromycin or moxifloxacin. For the full breakdown of dosing and how clinicians sequence it, see our guide to mgen treatment mgen treatment.
What treatment is actually like
You'll take pills over a couple of stretches rather than one dose. Doxycycline comes first, and it's well known for stomach upset — take it with food and a full glass of water, and don't lie down right after to avoid irritating your esophagus. It can make your skin burn more easily in the sun, so go easy on direct exposure during the course.
The biggest practical mistake is stopping early once symptoms ease. The two-step design is deliberate: the first drug lowers the load so the second can clear what's left, and skipping the back half lets resistant strains survive and rebound. Finish every dose even when you feel fine. If you're prescribed moxifloxacin, your clinician will go over the rare-but-real warnings that come with fluoroquinolones — bring up any tendon, heart, or nerve issues so they can weigh that for you.
Do partners need treating?
Yes — untreated partners are the classic route to reinfection, where a treated couple passes the same bug back and forth. Partners of someone with symptomatic Mgen can be tested and treated if positive, which lowers that reinfection risk. Avoid sex until both of you have completed treatment and any recommended retesting is done. Because Mgen spreads through genital-to-genital and oral-genital contact, the same exposure logic applies to recent partners; our overview of how it spreads how mycoplasma genitalium spreads explains who's worth notifying.
Follow-up, retesting, and test-of-cure
Mgen is one of the infections where a test-of-cure makes sense, because treatment fails more often than with other STIs. Your clinician may recommend repeat testing after you finish the full course to confirm the bacterium is gone, and to catch a resistant strain that needs the alternate drug. Don't retest too early — testing right after treatment can pick up dead organisms and give a false positive, so follow the timing your clinic sets. If you were tested soon after a possible exposure, our guide on when to test when to test after exposure explains why timing matters for an accurate result.
What happens if Mgen goes untreated
Mgen is an emerging cause of urethritis (inflammation of the urethra, the tube that carries urine) and cervicitis (inflammation of the cervix), and left alone it doesn't sit quietly. In men, it's a leading driver of persistent or recurrent urethritis — the burning, discharge, or irritation that keeps coming back despite earlier antibiotics, often because the wrong drug was used.
In women the stakes are higher. Untreated Mgen is linked to pelvic inflammatory disease (PID, infection that spreads up into the uterus and tubes and can scar them), to preterm delivery in pregnancy, and to infertility — with research pointing to roughly a twofold increase in infertility risk. Those tubal and reproductive consequences are why awareness and prompt, correct treatment matter so much, even when symptoms feel mild. For the broader picture of how the infection behaves, see our overview mycoplasma genitalium.
Preventing Mgen going forward
Condoms used every time lower the risk of passing or catching Mgen, and they're the most reliable single tool you control. The infection is often silent, so routine testing is what catches it before it spreads or scars. After you've cleared an infection, the smartest habits are consistent barrier use with new partners, prompt evaluation if symptoms return, and making sure partners are tested rather than guessing.
- Use condoms consistently rather than occasionally — partial use leaves the gaps where transmission happens.
- Get screened if you have new or multiple partners, or symptoms that won't quit.
- Ask specifically for an Mgen test when urethritis or cervicitis keeps returning, since it isn't on every standard panel.
- Have partners evaluated so you don't re-acquire the same strain.
When to see a clinician
See a clinician if you have burning with urination, unusual discharge, pelvic or testicular pain, or bleeding between periods or after sex — especially if a prior antibiotic didn't fully clear things. Recurrent urethritis or cervicitis that resists treatment is a strong reason to ask specifically about Mgen. Testing is straightforward: most cases are diagnosed from a urine sample or a self-collected swab, with results usually back in a few days, and it's free or low-cost at health departments, Planned Parenthood, and Title X clinics. You can get tested get tested or compare testing providers to find an option that reports Mgen and its resistance markers.
An Mgen diagnosis is common and treatable, clinics manage it routinely, and it says nothing about you as a person. The hard part is getting the right antibiotics, not the diagnosis itself.