Mycoplasma genitalium (Mgen) treatment usually runs about a week and a half: doxycycline first, then a second antibiotic chosen by whether the strain resists macrolides. Many people carry it with no symptoms, especially women. Skip sex until you and any partners finish the full course to avoid passing it back and forth.
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 |
The essentials: what Mgen actually is
Mycoplasma genitalium is one of the smallest bacteria that infect humans, and it lacks a cell wall. That single feature drives almost everything about how it's treated. Beta-lactam antibiotics — the penicillins and cephalosporins that work for many infections — attack the bacterial cell wall, so they do nothing here CDC, 2021. It's an emerging cause of urethritis (inflammation of the urethra, the tube urine passes through) and cervicitis (inflammation of the cervix), and the central problem with it is antibiotic resistance, particularly to the macrolide class.
If you want the full background on the organism and how it spreads, our mycoplasma genitalium overview covers it. Awareness matters because it's easy to miss — awareness is key in mg diagnosis and treatment.
Symptoms: is it always asymptomatic?
No. A large share of people never notice anything, and that's truer for women than men. When symptoms do show up, they differ by anatomy.
- In men, Mgen is a leading cause of non-gonococcal urethritis: a discharge from the penis and dysuria (burning or pain when you pee). It's often the kind of urethritis that keeps coming back or never fully clears after treatment for something else.
- In women, it tends to cause cervicitis, which can be silent or show up as abnormal discharge or bleeding, and can climb upward to cause pelvic inflammatory disease (an infection of the uterus and tubes that can threaten fertility).
- In many people of both sexes there are no symptoms at all, so it spreads under the radar and routine testing catches what an exam alone would miss.
Because so much of it is silent, Mgen can sit and cause low-grade inflammation for a while. For the downstream problems it's linked to, see mgen complications.
Testing: how Mgen is diagnosed
Mgen is detected with a NAAT (nucleic acid amplification test), a molecular test that finds the bacterium's genetic material. There are FDA-cleared options that run on urine or on a urethral, penile-meatal, endocervical, or vaginal swab, and several of those samples can be self-collected. In practice that means a urine cup or a quick swab, with results usually back in a few days.
It isn't on every standard STI panel, though, so you often have to ask for it specifically. Current guidance reserves testing for the situations where it's most likely to matter: men with recurrent NGU and women with recurrent cervicitis NYSDOH/JH. Macrolide-resistance testing should guide which drug you get, but it isn't commercially available in the US yet, so clinicians frequently have to treat as if resistance is present.
Testing is widely accessible and often free or low-cost at health departments, Planned Parenthood, and Title X clinics. If you're trying to time it after a possible exposure, read when to test after exposure, and you can get tested when you're ready.
Treatment: how long, and what to expect
Mgen treatment is resistance-guided and given in two steps, always starting with doxycycline. The doxycycline phase doesn't usually cure the infection on its own; it lowers the bacterial load so the second drug works better.
What the second drug is depends on whether the strain resists macrolides:
| Scenario | Step 1 | Step 2 |
|---|---|---|
| Macrolide-sensitive strain | Doxycycline 100 mg twice daily for 7 days | Azithromycin 1 g once, then 500 mg daily for 3 days |
| Macrolide-resistant strain, or resistance testing unavailable | Doxycycline 100 mg twice daily for 7 days | Moxifloxacin 400 mg daily for 7 days |
So the typical course spans roughly a week and a half from the first doxycycline dose through the end of the second antibiotic. Resistance is what makes it this involved. The old approach of a single azithromycin dose now fails often because macrolide-resistance mutations have climbed past half of infections in many areas — over 62% in one US STI clinic. A specific M. genitalium test, rather than a generic panel, lets a clinician choose correctly.
A few practical points matter more than people expect. Finish every pill even after you feel better, because stopping early helps resistance build. Ask whether your partner needs treating, since reinfection from an untreated partner is common. And don't count on a quick same-day fix; this is a defined, sequenced course rather than a single shot.
Can you have sex during treatment?
Hold off. Avoid sex until you've completed the full course and any partner being treated has finished theirs, or you risk passing it back and forth and undoing the treatment. Condoms used every time lower the risk of transmitting Mgen and the other sexually transmitted infections, and partners of someone with symptoms can be tested and treated if they're positive to cut down reinfection.
Prevention
- Use condoms consistently — every time — to lower transmission risk for Mgen and other STIs.
- Get tested routinely, since Mgen is so often symptom-free.
- Loop partners in. Testing and treating an infected partner keeps you from getting reinfected after you've finished your own course.
When to see a clinician
Get checked if you have penile discharge or burning with urination, abnormal vaginal discharge or bleeding, pelvic pain, or urethritis or cervicitis that came back or never cleared after treatment. Recurrent symptoms are the classic Mgen flag. A diagnosis here is common and treatable; clinics handle it routinely, and it says nothing about you as a person.
Mgen FAQ
How long does Mgen treatment take?
It's a two-step course — doxycycline for the first stretch, then a second antibiotic for several more days — so the whole thing runs about a week and a half. Take every dose to the end.
Can Mgen be asymptomatic?
Yes, very often, and especially in women. Many people have no discharge, no burning, and no idea they carry it, so it spreads quietly and testing matters when symptoms keep recurring.
Why isn't a single azithromycin dose enough anymore?
Because macrolide resistance has become so common — past half of infections in many places — the old single-dose approach frequently fails. Current treatment leads with doxycycline and then picks azithromycin or moxifloxacin based on resistance.
Why don't penicillin-type antibiotics work?
Mgen has no cell wall, and penicillins and cephalosporins kill bacteria by attacking the cell wall. With no wall to target, those drugs simply don't affect it.
Is Mgen on a standard STI panel?
Often not. You usually have to request the specific M. genitalium test, and guidance focuses it on men with recurrent urethritis and women with recurrent cervicitis rather than testing everyone.
Do I need a test of cure?
Follow your clinician's plan. Treatment usually fails because pills get stopped early or a partner reinfects you, so finishing the full course and getting partners checked do the most to prevent a repeat.
When can I have sex again?
After you've completed the entire course and any partner being treated has finished too. Resuming earlier risks passing it back and forth.
Should my partner get treated?
Ask your clinician. Partners of someone with symptoms can be tested and treated if positive, which is the main way to stop reinfection once you're done.