Male Chlamydia: Symptoms, Incubation Period, Treatment & Risks Explained by a Doctor [2026]

What Is Male Chlamydia? Japan’s Most Common STI

Chlamydia is a sexually transmitted infection caused by the bacterium Chlamydia trachomatis. According to surveillance data from Japan’s National Institute of Infectious Diseases, approximately 30,000 cases of genital chlamydia are reported each year, making it the most common STI in Japan.

The main route of transmission is sexual contact (vaginal, oral, or anal sex), with the bacterium spreading through contact with semen, vaginal secretions, or mucosal surfaces of an infected person. Chlamydia is an obligate intracellular bacterium that can only replicate inside host cells, infecting the mucosal epithelium of the urethra, pharynx, rectum, and conjunctiva.

In men, chlamydia most often presents as urethritis, and about 50% of cases have only mild symptoms or none at all. “Mild symptoms” does not mean “low virulence” – leaving the infection untreated can lead to the complications described below, including epididymitis, reactive arthritis, and infertility.

How Chlamydia Spreads: Over 95% via Sexual Contact

Almost 100% of chlamydia transmission occurs through sexual contact. The main routes include:

• Vaginal sex: The most common route. The estimated per-act transmission rate is roughly 30-50% in either direction (man-to-woman or woman-to-man).
• Oral sex: Causes infection of the pharynx (throat) via fellatio or cunnilingus.
• Anal sex: Causes rectal infection. A key risk factor for men who have sex with men (MSM).
• Vertical transmission: A newborn can be infected during delivery through the birth canal, sometimes causing neonatal conjunctivitis or pneumonia.

Transmission through everyday contact – kissing, towels, toilet seats, or bathtubs – is extremely unlikely. Chlamydia spreads via mucosa-to-mucosa contact, so even if bacteria land on the skin surface, infection rarely takes hold.

That said, infection is not limited to the genitals – it can also occur in the pharynx, rectum, and conjunctiva, so it is important to recognize that oral sex can transmit chlamydia. For details, see our article on pharyngeal chlamydia.

Cases in Japan: Rising Among Men in Their 20s and 30s

Data from Japan’s National Institute of Infectious Diseases show that reported cases of genital chlamydia (men and women combined) have hovered between 28,000 and 30,000 per year, with a slight upward trend since the late 2010s. Reported cases are only the tip of the iceberg – including asymptomatic infections, the actual number is estimated to be 5-10 times higher.

By age group, the trends are as follows:

• Men aged 20-24: Peak of notified cases – the period of highest sexual activity.
• Men aged 25-29: The second most affected age group.
• Men aged 30-34: An age range where re-infection from a partner becomes more common.
• Men aged 40 and older: Fewer reported cases, but asymptomatic infection is more often missed.

Chlamydia is often viewed as “a young man’s disease,” but in reality it can affect any age group with sexual activity. Past infections can resurface even in long-term monogamous relationships, so early testing is recommended whenever symptoms appear.

Symptoms in Men: Urethritis, Discomfort, and Discharge

When men acquire chlamydia, the most common presentation is chlamydial urethritis. Symptoms are typically milder than those of gonococcal urethritis, and it is the leading cause of “non-gonococcal urethritis.”

The main symptoms include:

• Urethral itching or tingling: The most common initial symptom – a feeling similar to rubbing against underwear.
• Urethral discharge (pus): Clear to cloudy, mucous-like discharge. The yellow purulent discharge typical of gonorrhea is uncommon.
• Pain on urination (dysuria): A stinging or prickling sensation when urinating. Usually milder than gonorrhea.
• Redness and discomfort at the urethral opening: Slight redness at the urethral meatus.
• Stained underwear: Thin discharge noticed on underwear in the morning.

These symptoms are typically only about 20-30% as intense as those of gonorrhea, which is why they are so easily overlooked. Brushing it off as “just a little itch” or “it cleared up on its own” allows the bacteria to persist in the body and raises the risk of complications.

Chlamydial vs. Gonococcal Urethritis: Symptom Comparison

In male urethritis, symptom severity differs substantially depending on the causative organism. A comparison between chlamydia and gonorrhea is shown below.

*Adapted from the Japanese Society for Sexually Transmitted Infections’ STI Diagnosis and Treatment Guidelines 2020.

As shown above, chlamydia is characterized by “mild and ambiguous” symptoms. Meanwhile, co-infection with gonorrhea occurs in 20-30% of cases, and symptoms alone cannot distinguish the two, so testing for both pathogens at the same time is recommended. For details on gonorrhea, see our article on male gonorrhea symptoms and treatment.

Incubation Period: 1-3 Weeks as a Rule of Thumb

The incubation period for chlamydia – the interval between infection and symptom onset – is generally 1-3 weeks (average 2 weeks). This represents the time required for Chlamydia trachomatis to multiply inside host cells and reach a sufficient bacterial load.

However, there is significant individual variation, with patterns such as:

• Within 1 week: Early onset when bacterial load is high or host immunity is weakened.
• 2-3 weeks: The standard incubation period – the most common pattern.
• 1-2 months: Delayed onset due to immune status.
• Asymptomatic throughout: About 50% of men and 80% of women.

Even during the incubation period, infected people are contagious to others. Continuing sexual activity under the assumption that “I am fine because I have no symptoms” leads to further transmission to partners. If at least one week has passed since a potential exposure, testing is possible regardless of whether symptoms are present.

When Should You Get Tested? Recommended Timing

The recommended timing for chlamydia testing varies with the time elapsed since possible exposure.

• Within 24 hours of exposure: Bacterial load is too low for reliable detection – testing is not recommended.
• 24 hours to 1 week after exposure: PCR (nucleic acid amplification testing) may be able to detect the infection, but reliability is low.
• 1-2 weeks after exposure: The recommended starting window – PCR accuracy becomes stable.
• 3+ weeks after exposure: Both antigen tests and PCR can detect the infection with high accuracy.
• 2-4 weeks after treatment: Recommended timing for follow-up “test of cure.”

If you have symptoms, seek care even if a week has not yet passed. In some cases treatment can be started based on symptoms without waiting for test results.

The Danger of Asymptomatic Chlamydia: Silent Transmission

The biggest issue with chlamydia is that about 50% of men and 80% of women remain asymptomatic (or have only extremely mild symptoms). This is the fundamental reason chlamydia is the most common STI in Japan.

The problems caused by asymptomatic infection include:

• The patient never realizes they are infected: The infection is found only through testing.
• Continued transmission to partners: Every sexual encounter potentially creates a new infection.
• Progression of complications: Inflammation continues internally even without symptoms.
• “Ping-pong” infection: Couples repeatedly re-infect each other.

It is essential to recognize that “no symptoms” does not mean “no infection.” If you have had a risky sexual encounter, regular testing – regardless of symptoms – is the only way to protect yourself and your partners.

Preventing Ping-Pong Infection: The Importance of Treating Partners Together

“Ping-pong” infection describes the phenomenon in which couples or partners repeatedly pass chlamydia back and forth. If only one person is treated and the other carries the infection, re-infection occurs with each sexual encounter.

To prevent ping-pong infection:

• Notify your partner: Once you test positive, encourage your partner to get tested too.
• Simultaneous treatment: If your partner is also positive, start treatment at the same time.
• No sex during treatment: Abstain from sex for at least 7 days from the start of treatment.
• Resume only after confirmed cure: Wait until a follow-up test confirms a negative result before resuming sex.
• Use condoms: Use condoms consistently until cure is confirmed.

Telling a partner can feel awkward, but the right framing is: “staying silent is what hurts your partner.” Our clinic also offers support for partner notification.

Risks of Leaving It Untreated: Epididymitis, Infertility, Reactive Arthritis

If chlamydia is left untreated, the bacteria can ascend retrogradely from the urethra to the testes and prostate, potentially causing the following serious complications:

• Chlamydial epididymitis: Painful swelling of one side of the scrotum, sometimes with fever.
• Chlamydial prostatitis: Perineal pain, difficulty urinating, urinary frequency. Tends to become chronic.
• Male infertility: Obstruction of the epididymis or vas deferens that impedes sperm transport.
• Reactive arthritis (formerly Reiter’s syndrome): The classic triad of arthritis, urethritis, and conjunctivitis.
• Increased HIV transmission risk: Active chlamydia infection raises the risk of HIV acquisition 2-5 fold.

All of these complications take longer to treat and may leave lasting sequelae. Rather than dismissing chlamydia as “mild,” get tested and treated as soon as you notice any abnormal sensation – that is the most important point.

Chlamydial Epididymitis: Symptoms and Treatment

Epididymitis is inflammation of the epididymis, which sits above and behind the testis. In men under 35, most cases of epididymitis are caused by chlamydia.

The main symptoms include:

• Scrotal swelling: Usually one-sided, gradually enlarging.
• Scrotal pain and tenderness: Worse with movement; aggravated when sitting.
• Fever: May include fever above 38 degrees C.
• Pain on urination: Often accompanied by urethritis symptoms.
• Inguinal lymphadenopathy: Swelling of lymph nodes on the affected side.

Treatment requires prolonged antibiotic therapy (2-3 weeks) – longer than for isolated urethritis. Severe cases may require hospitalization. Early treatment can prevent obstruction of the vas deferens, but bilateral inflammation or delayed treatment can lead to male infertility, so prompt care is important.

Reactive Arthritis (Reiter’s Syndrome): Rare but Important

Reactive arthritis (formerly Reiter’s syndrome) is an immune-mediated arthritis triggered by infections such as chlamydia. It occurs in roughly 1-3% of men with chlamydia, with higher risk in HLA-B27-positive individuals.

Classically, it presents with the following triad:

• Arthritis: Often in large joints of the lower limbs (knees, ankles); asymmetric.
• Urethritis: The initial lesion due to chlamydial infection.
• Conjunctivitis: Redness and discharge in both eyes.

The full triad is often incomplete, and joint pain alone may appear first. Because it can be mistaken for a rheumatic disease, telling your doctor about any history of STIs is key to diagnosis. Treatment combines eradication of chlamydia with non-steroidal anti-inflammatory drugs (NSAIDs) for the arthritis.

Pharyngeal and Rectal Chlamydia: Infection Beyond the Genitals

Chlamydia can infect mucosa outside the genitals as well. The most common examples are pharyngeal chlamydia and rectal chlamydia.

Pharyngeal chlamydia infects the throat mucosa via oral sex (fellatio or cunnilingus), and 80-90% of infected people are asymptomatic. When symptoms occur, they tend to be mild – slight throat discomfort, cough, or low-grade fever – and are hard to distinguish from the common cold. For details, see our article on pharyngeal chlamydia symptoms and treatment.

Rectal chlamydia is acquired via anal sex and infects the rectal mucosa – it is more common among men who have sex with men (MSM). Symptoms include anal pain, painful bowel movements, and mucous or bloody discharge, but most cases are still asymptomatic. Severe cases can present as chlamydial proctitis, with chronic anal lesions.

Why Simultaneous Pharyngeal and Rectal Testing Is Recommended

A positive genital chlamydia test can mean that pharyngeal or rectal infection is also present. Clinical data show the following trends:

• Pharyngeal co-infection in patients with genital chlamydia: About 10-15%.
• Rectal co-infection in patients with genital chlamydia: About 20-30% in MSM.
• If there is a history of oral sex: Even after genital treatment, the pharynx can be a source of re-infection.

For patients with a risky sexual exposure, we recommend simultaneous testing of three sites – genital, pharyngeal, and rectal. Testing only one site can miss infections that later cause re-infection after treatment.

Testing Methods: PCR and Urine Testing

The mainstream test for male chlamydia is a nucleic acid amplification test (NAAT) of the PCR type. With high sensitivity and specificity, it is the first-line option in the Japanese STI Diagnosis and Treatment Guidelines 2020.

The main tests used in men are:

• First-void urine PCR: Collect the first 10-20 mL of urine – painless and easy, with sensitivity above 95%.
• Urethral swab PCR: A swab is inserted at the urethral opening – slightly uncomfortable but highly accurate.
• Pharyngeal gargle PCR: Gargle with saline for 15 seconds and the rinse is tested.
• Rectal swab PCR: A thin swab is inserted into the anus to collect secretions.
• Combined NG/CT test: Simultaneous detection of both gonorrhea and chlamydia from one sample.

Results are usually available within 2-5 business days. To protect privacy, our clinic also offers an online “My Page” system where results can be reviewed online.

Antibody Testing (IgA / IgG): When It Is Useful

Antibody (blood) testing for chlamydia serves a different purpose than PCR.

• IgA antibody: Rises 5-6 weeks after infection – indicates current or recent infection.
• IgG antibody: Rises after 4+ weeks – indicates past or current infection.

Antibody testing is useful as an adjunct for past infections or deep-organ infections (epididymitis, pelvic inflammatory disease). However, agreement with antigen tests (PCR) is only about 30%, so PCR is preferred for acute diagnosis.

Because antibodies can remain positive for a long time after treatment, they cannot be used to confirm cure. A test-of-cure should be done with a repeat PCR 2-4 weeks after treatment.

Treatment: Azithromycin and Doxycycline

The basis of chlamydia treatment is oral antibiotics. The agents recommended in the Japanese STI Diagnosis and Treatment Guidelines 2020 are:

• Azithromycin (Zithromax) 1 g: A single oral dose – treatment is complete. Macrolide class.
• Doxycycline (Vibramycin) 100 mg: Twice daily for 7 days. Tetracycline class.
• Clarithromycin (Claris) 200 mg: Twice daily for 7 days. Macrolide class.
• Levofloxacin (Cravit) 500 mg: Once daily for 7 days. New-quinolone class.
• Sitafloxacin (Gracevit) 100 mg: Twice daily for 7 days. Newer-quinolone class.

The first-line option is a single 1 g dose of azithromycin. Because treatment is completed with one administration, adherence is high, and it is widely used as the standard treatment for chlamydial urethritis in men.

Choosing the Right Drug Based on Site and Comorbidities

The choice of medication depends on the infection site and any complications.

*Adapted from the STI Diagnosis and Treatment Guidelines 2020.

Reports of macrolide-resistant chlamydia have been increasing in recent years, so a follow-up test-of-cure after treatment is recommended. If the post-treatment test is positive, the regimen is switched.

During Treatment: No Sex and Confirm Cure

For treatment to succeed, please observe the following:

• No sex for at least 7 days after starting treatment: Prevents transmission to your partner.
• Partner should also be tested and treated: Prevents ping-pong infection.
• Test of cure at 2-4 weeks post-treatment: Repeat PCR to confirm cure.
• Finish the entire course: Stopping early can lead to resistance.
• Limit alcohol: It can affect antibiotic metabolism.
• Screen for co-infections: Simultaneous screening for gonorrhea, syphilis, and HIV is recommended.

With appropriate treatment, more than 95% of chlamydia cases are fully cured. Early detection and early treatment prevent complications and let you confidently maintain a healthy relationship with your partner.

Co-Infection with Gonorrhea and General STI Knowledge

In male urethritis, 20-30% of cases involve co-infection (combined infection) with chlamydia and gonorrhea. The two can be hard to distinguish clinically due to similar symptoms and course, so testing for both pathogens at once is recommended.

When chlamydia and gonorrhea co-infect, both must be treated. A typical regimen is:

• Ceftriaxone (Rocephin) 1 g intravenous injection: First-line for gonorrhea.
• Azithromycin 1 g oral: First-line for chlamydia.
• Same-day administration: Both can be completed in one visit.

For details on gonorrhea symptoms and treatment, see our article on male gonorrhea. For an overview of STIs and a symptom checklist by type, see our male STI list and symptom guide.

Preventing Chlamydia and Other STIs: Condoms and Regular Testing

Effective measures to prevent chlamydia and other STIs include:

• Correct condom use: Use from start to finish – mid-act application does not work.
• Condoms or dental dams during oral sex: Prevents pharyngeal infection.
• Regular STI testing: Test whenever you start with a new partner.
• Manage your number of partners: Avoid casual contact with multiple partners.
• See a doctor early when symptoms appear: Within a few days of noticing anything unusual.
• Share information with your partner: Mutual disclosure of STI history and recent test results.

When it comes to STIs, the assumption “I am fine, it will not happen to me” is the biggest driver of transmission. We recommend treating an STI screening once or twice a year like any other regular health check.

STI Treatment at Men’s Care Clinic

At Men’s Care Clinic, we offer a system that allows you to complete STI testing and treatment – including for chlamydia – entirely through online consultation. Without coming to the clinic, you can receive a home test kit, self-collect a sample, return it by mail, and – if positive – receive prescribed treatment after consulting with a physician.

• Online consultation: See a physician from your smartphone or PC.
• Home test kit: Self-collect samples at home – no clinic visit required, privacy preserved.
• Three-site testing available (genital, pharyngeal, rectal): Prevents missed infections.
• Combined gonorrhea / chlamydia testing (NG/CT): Detects co-infection.
• Same-day prescription and shipping when positive: Treatment can start immediately.
• Partner notification support: Our physicians can help with awkward conversations.
• Men-only clinic with male staff: Easier to discuss with same-sex staff.

We welcome inquiries such as “I have no symptoms but had a risky encounter” or “I would like a check-up just to be sure.” Chlamydia is a disease that can be fully cured with early detection and early treatment. If you have any concerns, start with an online consultation.

Frequently Asked Questions (FAQ)

Q1. Does chlamydia clear up on its own?

Spontaneous resolution of chlamydia is essentially not to be expected. Without antibiotic treatment, the bacteria persist in the body and develop into a chronic infection. Symptoms may disappear temporarily, but this is not “cure” – it is simply entry into an asymptomatic phase. The infection still spreads and the risk of complications continues.

The most dangerous misconception is “the symptoms are gone, so I am cured.” Always see a medical provider and receive both antibiotic treatment and a test-of-cure.

Q2. How long does chlamydia treatment take?

For genital chlamydia (uncomplicated urethritis), treatment is complete with a single 1 g dose of azithromycin. One administration keeps effective blood levels for about 7 days.

However, treatment is longer in the following cases:

• With epididymitis: Doxycycline for 10-14 days.
• Rectal chlamydia: Doxycycline for 7 days.
• Co-infection with gonorrhea: Ceftriaxone injection plus oral azithromycin.

A test-of-cure (PCR) 2-4 weeks after treatment is recommended to confirm there is no resistance or re-infection.

Q3. Can you get chlamydia more than once?

Yes, you can be re-infected with chlamydia repeatedly. Unlike measles or chickenpox, a single infection does not confer lifelong immunity. Even after a complete cure, you can be re-infected through sex with an infected partner.

To prevent re-infection:

• Treat your partner at the same time: Prevents ping-pong infection.
• Use condoms reliably: From start to finish of every sexual act.
• Make regular testing a habit: Test with every new partner, or at least every six months.
• Wait for a confirmed cure before resuming sex: Avoid sex until a negative test of cure.

One round of treatment does not guarantee you will never be infected again. During periods of active sexual activity, we recommend regular testing 1-2 times per year.

Q4. Should I get tested even if I have no symptoms?

Yes – if you have had a risky sexual encounter, testing is strongly recommended even without symptoms. About 50% of male chlamydia cases are asymptomatic, and you will not know you are infected unless you get tested.

You should be tested regardless of symptoms if any of the following apply:

• You had unprotected sex with a new partner.
• Your partner may have had unprotected sex with someone else.
• Your partner has been diagnosed with an STI.
• You used commercial sex services.
• You have not been tested for STIs in the past 6+ months.

Our clinic accepts test requests with or without symptoms, and results are communicated together with a physician consultation.

Q5. Can chlamydia cause male infertility?

Yes – leaving chlamydia untreated can cause male infertility. Specifically, bilateral chlamydial epididymitis can obstruct the vas deferens and prevent sperm passage, leading to “obstructive azoospermia.”

However, it is important to keep these points in mind:

• Most cases are unilateral epididymitis: The contralateral testicle usually retains its function.
• Early treatment can prevent ductal obstruction: Treating at the urethritis stage avoids complications.
• The absolute risk of infertility is not high: Although the risk of bilateral disease is not zero.
• The infertility risk is higher for female partners: Tubal occlusion occurs in 30-40% of women.

If you are diagnosed with chlamydia, testing and treatment for your partner (especially female partners) is essential, not just for you. For anyone planning future pregnancy, early treatment is critical.

Q6. How are chlamydia and gonorrhea different?

Both chlamydia and gonorrhea are common STIs causing urethritis in men, but the causative organism, symptom severity, and treatment differ.

• Causative organism: Chlamydia trachomatis (bacterium) vs. Neisseria gonorrhoeae.
• Incubation period: Chlamydia 1-3 weeks; gonorrhea 2-7 days.
• Symptom severity: Chlamydia is mild to asymptomatic; gonorrhea is acute and severe.
• Discharge: Chlamydia – clear to cloudy and small in volume; gonorrhea – yellow to green and large in volume.
• Treatment: Chlamydia – oral azithromycin; gonorrhea – ceftriaxone injection.

Because co-infection occurs in 20-30% of cases, testing for both is standard. For more details, see our article on male gonorrhea.

Q7. How much does chlamydia testing cost?

The cost of a chlamydia test varies depending on what is tested and whether it is covered by insurance.

• Chlamydia-only test (PCR): Around 3,000-6,000 yen.
• Combined gonorrhea / chlamydia test (NG/CT): Around 5,000-8,000 yen.
• Full STI panel (including HIV, syphilis, hepatitis B, hepatitis C): Around 15,000-25,000 yen.
• Consultation and shipping fees apply separately: Varies by clinic.

If symptoms are present, testing can be done under insurance coverage, with a 30% patient share. Asymptomatic testing is generally provided as self-pay (uninsured). Our clinic accommodates either option depending on your needs.

Q8. Should I tell my partner about a positive result?

Yes – partner notification is strongly recommended. Even after you complete treatment, if your partner is still carrying the infection, re-infection will occur with every sexual encounter (ping-pong infection).

Points to consider when telling a partner:

• Share facts rather than assign blame: Frame it as “let us both get tested.”
• Explain that asymptomatic infection is possible: Counter the assumption “no symptoms = no infection.”
• Explain the importance of simultaneous treatment: Describe ping-pong infection.
• Suggest where they can be seen: Help your partner find a clinic.

Our clinic also offers partner notification support. If you are not sure how to bring it up, talk to your physician. We can help prepare explanation documents and assist with booking your partner’s appointment.