Chlamydia treatment may fail twice due to bacterial resistance to antibiotics, issues with the absorption of medication into the body, or not following the full course of antibiotics. People may also have a repeat infection rather than treatment failure.

Chlamydia is a bacterial infection that doctors may treat by prescribing antibiotics, such as azithromycin, doxycycline, or levofloxacin.

This article looks at why chlamydia treatment may fail twice, how commonly this occurs, and the next steps to take.

A note about sex and gender

Sex and gender exist on spectrums. This article will use the terms “male,” “female,” or both to refer to sex assigned at birth. Click here to learn more.

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Possible reasons for treatment failure include:

  • bacterial resistance to antibiotic treatment
  • medication that does not absorb properly into the body
  • ineffective coverage of antibiotic medication
  • interrupting or not taking antibiotic treatment for the full course

Bacterial resistance to azithromycin is a common cause of chlamydia treatment failure. Research shows a 41.4% prevalence of mutations in chlamydia strains that may be resistant to this medication.

In males, research has shown that treatment failure was higher with azithromycin than with doxycycline. In men who have sex with men, reports have shown 100% treatment success with doxycycline and 74% success with azithromycin.

Therefore, doxycycline may be more effective than azithromycin for treating rectal infections in both males and females.

Most cases of chlamydia infection after treatment are due to treatment failure but repeat infections. This may be due to sexual partners not receiving treatment or as a result of sexual contact with a new partner with a chlamydia infection.

It is also possible for a chlamydia test to produce a false-positive result, meaning that a test result is positive, but there is no active infection. This may occur because the chlamydia infection is still clearing from the body, meaning a test still detects it.

How long does a person test positive for chlamydia after treatment?

Healthcare professionals use nucleic acid amplification tests (NAATs) to diagnose chlamydia. However, NAATs cannot differentiate between chlamydia nucleic acid when it is nonviable (dead) and when it is viable (active).

This means that if people have a NAAT while a chlamydia infection is still clearing from the body, it may cause a positive test result.

According to a 2016 article, chlamydia testing may produce a positive result if it is within 14 days after beginning treatment.

If people have a positive result shortly after 14 days, it is most likely a false-positive result rather than treatment failure or repeat infection.

A test of cure (TOC) is a requirement as standard care of practice. It can help detect whether or not the treatment has failed. Doctors encourage people to schedule a follow-up appointment at the time of treatment. A TOC tests for chlamydia 4 weeks after a person has completed treatment.

Research suggests that treatment failure with azithromycin may occur between 5% and 23% of cases.

It is very common to have repeat infections of chlamydia. In the first few months following treatment for initial infection, as many as 1 in 5 people will experience reinfection.

If people experience reinfection after antibiotic treatment resulting in a negative test result, it is usually due to reinfection from a sexual partner.

If people have repeated positive test results after treatment, it may be due to false-positive results or treatment failure. Resistance to antibiotic treatment is rare in chlamydial infections.

Repeat infections may occur at any time, but research suggests that most reinfections happen within the first 6 months after treatment.

If people have had a positive test following treatment, but their medical history suggests it may be a false-positive, they can get a repeat test to confirm the result.

People should abstain from sexual intercourse until they have received a negative TOC. Barrier methods of protection, such as condoms, can help prevent transmission and reinfection.

A 2020 article recommends that people who test positive for chlamydia will need to undergo another screening 3 months following treatment to test for a repeat infection.

If chlamydia treatment is ineffective, the next steps may involve:

  • Asking sexual partners to get tested: Repeat infections are usually due to sex with a partner who has chlamydia but has not received treatment. Therefore, it is important for sexual partners to receive testing promptly.
  • Asking sexual partners to go with them to receive treatment: When returning for testing or treatment, a person can bring their sexual partner or partners with them if possible so they can also receive testing and treatment.
  • Getting a retest: Seeking a retest for both chlamydia and gonorrhea is important, as people at risk of chlamydia infections may also be at risk for gonorrhea.
  • Being open: At the appointments, it is important for people to inform a healthcare professional about all sexual partners within the last 2 months.

If a chlamydial infection is persistent despite taking the above steps, a healthcare professional may recommend a combination therapy to treat a chronic chlamydia infection.

Clinics or healthcare facilities can also educate people on minimizing the risk of recurrent infections and setting reminders that increase return rates for testing.

Why is it important to receive treatment?

Untreated chlamydia may increase the risk of developing HIV if a person contracts the virus.

Repeat chlamydia infections in females increase the risk of serious complications, such as:

In pregnant people, untreated chlamydia can result in:

  • preterm delivery
  • neonatal conjunctivitis, where a newborn develops red eye due to infection
  • neonatal pneumonia, where a baby develops a lung infection shortly after birth

Additionally, in males, untreated chlamydia infections may lead to fertility problems.

If chlamydia treatment fails twice, it may be due to antibacterial resistance, lack of adherence to a treatment regimen, or issues with absorbing antibiotics into the body.

It is also common to get chlamydia more than once, so it may be a repeat infection rather than treatment failure. It is also possible to have a false-positive test result shortly after treatment.

It is important to attend follow-up testing after chlamydia treatment to check for recurrence.

Ensuring all recent sexual partners get prompt testing and treatment, taking all antibiotic treatments as a doctor prescribes, and abstaining from sex during treatment may all help prevent recurring infections.