Chlamydia Treatment: Antibiotics, Timeline, and What to Expect

Chlamydia treatment is straightforward: a short course of antibiotics clears the infection reliably in almost everyone. The clinical challenges are elsewhere — detecting an infection that is asymptomatic in most people, ensuring partners are treated to prevent immediate reinfection, and confirming clearance in the populations where treatment failure is most consequential.

Quick answer: The CDC-recommended first-line treatment for chlamydia is doxycycline 100mg twice daily for 7 days. Azithromycin 1g single dose is an alternative when adherence is a concern. Abstain from sex for 7 days after completing treatment (or until your partner completes theirs). Retest 3 months after treatment. Confidential same-day testing available in Los Angeles, Dallas, Orlando, New York City, and Seattle.

First-Line Treatment: Doxycycline

Doxycycline 100mg orally twice daily for 7 days is the current CDC-recommended first-line regimen, updated from the previous azithromycin preference following data showing higher efficacy for doxycycline, particularly for rectal chlamydia infections. Azithromycin 1g single dose is an alternative — it remains effective for urogenital chlamydia and has practical advantages when treatment adherence is uncertain, but is less effective for pharyngeal and rectal infections.

Doxycycline should be taken with food to reduce gastrointestinal side effects. It causes photosensitivity — use sunscreen or avoid prolonged sun exposure during the 7-day course. It is contraindicated in pregnancy.

Treatment in Pregnancy

Doxycycline is contraindicated throughout pregnancy. The CDC recommends amoxicillin 500mg three times daily for 7 days as first-line in pregnancy. Azithromycin 1g single dose is an alternative. A test of cure — repeat NAAT testing — is recommended 3–4 weeks after completing treatment in pregnant patients, and again in the third trimester for high-risk patients, because untreated or undertreated maternal chlamydia causes neonatal conjunctivitis and pneumonia.

Partner Treatment

Both partners must be treated. Reinfection from an untreated partner is the most common reason for a positive test 3 months after treatment in otherwise adherent patients. The CDC recommends expedited partner therapy (EPT) — providing prescriptions or medication to the patient to give directly to their partners without requiring partners to attend a clinic — as an effective public health tool where legally permitted. Both partners should abstain from sex until 7 days after each has completed treatment.

What to Do After Treatment

Abstain from sex for 7 days after completing the course (or 7 days after a single-dose treatment). Retest at 3 months after treatment — not to confirm treatment success, but because reinfection from a new or untreated partner in the months following a positive test is common enough to warrant routine retesting regardless of symptoms. Inform all recent sexual partners (typically the previous 60 days, or the most recent partner if the last contact was more than 60 days ago) so they can be tested and treated.

Treatment Failure: When It Happens

True antibiotic treatment failure — the bacteria failing to clear despite correct antibiotic use — is rare with doxycycline for urogenital chlamydia. A positive NAAT test 3–4 weeks after completing treatment most often represents either reinfection from an untreated partner, incomplete treatment adherence, or a false positive from residual bacterial DNA (NAAT tests can remain positive for up to 3–4 weeks after successful treatment as dead bacterial DNA clears). Retesting before 3–4 weeks after treatment completion is not recommended for this reason.

When to Seek Urgent Care

• Pelvic pain, fever, or unusual vaginal discharge during or after treatment: possible PID developing from the chlamydia infection — requires same-day evaluation and IV or IM antibiotics.

• Testicular pain or swelling: possible epididymitis — same-day evaluation, may require additional or extended antibiotic treatment.

• Symptoms persisting more than a week after completing treatment: see a clinician to assess for reinfection or other cause.

Frequently Asked Questions

How long does chlamydia take to clear after treatment?

The bacteria are typically cleared within 7 days of completing doxycycline. Symptoms, when present, usually resolve within 1–2 weeks. However, NAAT tests can remain positive for 3–4 weeks after successful treatment due to residual bacterial DNA — retesting before this window produces unreliable results and is not recommended.

Can chlamydia come back after treatment?

Chlamydia can be acquired again after successful treatment — there is no lasting immunity. The most common cause of a positive test 3 months after treatment is reinfection from an untreated partner or new exposure, not treatment failure. This is why partner treatment and routine retesting at 3 months are both recommended.

Do I need to get tested after treatment?

Yes. Retesting 3 months after treatment is recommended by the CDC for all patients, regardless of symptoms. The purpose is to detect reinfection — which is common — not to confirm treatment success. In pregnant patients, a test of cure at 3–4 weeks post-treatment is additionally recommended.

What happens if chlamydia is left untreated?

In women, untreated chlamydia ascends from the cervix to cause pelvic inflammatory disease (PID), which causes progressive tubal scarring leading to infertility and ectopic pregnancy. The CDC estimates untreated chlamydia and gonorrhea cause approximately 24,000 preventable cases of infertility in US women annually. In men, untreated chlamydia can cause epididymitis and obstructive azoospermia. Both sexes can develop reactive arthritis from untreated chlamydia.

Related: Understanding Chlamydia · Chlamydia and Infertility · STDs With No Symptoms · When Can You Have Sex After Treatment? · Get tested today →