What is Chlamydia (Chlamydia trachomatis)?

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Last updated: May 27, 2025View editorial policy

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From the Guidelines

Chlamydia should be treated with a single 1-gram dose of azithromycin taken orally, or doxycycline 100mg taken twice daily for 7 days, as these regimens have been shown to be efficacious in treating the infection 1. The treatment of chlamydia is crucial in preventing the transmission of the infection to sex partners and reducing the risk of complications such as pelvic inflammatory disease in women and epididymitis in men.

  • The Centers for Disease Control and Prevention (CDC) recommend treating infected patients to prevent transmission to sex partners and reinfection of the index patient 1.
  • It is essential to complete the full course of antibiotics even if symptoms disappear before finishing treatment.
  • Sexual partners from the past 60 days should also be treated to prevent reinfection.
  • Abstain from sexual activity until both you and your partner(s) have completed treatment and symptoms have resolved, typically about 7 days after starting antibiotics.
  • Chlamydia often causes no symptoms, particularly in women, which is why regular screening is important for sexually active individuals.
  • When symptoms do occur, they may include abnormal discharge, burning during urination, or pain in the lower abdomen.
  • If left untreated, chlamydia can lead to serious complications, potentially resulting in fertility problems.
  • The infection spreads through unprotected vaginal, anal, or oral sex, and consistent condom use significantly reduces transmission risk.
  • For pregnant women, azithromycin is the preferred option as doxycycline is contraindicated during pregnancy 1.

From the Research

Chlamydia Overview

  • Chlamydia trachomatis infection most commonly affects the urogenital tract, with symptoms including dysuria and discharge from the penis in men, and minimal or no symptoms in women, although some may develop pelvic inflammatory disease 2.
  • Untreated chlamydial infection in men can spread to the epididymis, while in newborns, it can cause ophthalmia neonatorum, and chlamydial pneumonia can occur at one to three months of age 2.

Treatment Options

  • Treatment options for uncomplicated urogenital infections include a single 1-g dose of azithromycin orally, or doxycycline at a dosage of 100 mg orally twice per day for seven days 2, 3.
  • The recommended treatment during pregnancy is erythromycin base or amoxicillin 2.
  • A study found that a single 1-g dose of azithromycin is as effective for the treatment of uncomplicated genital chlamydial infections as a standard seven-day course of doxycycline 3.

Effectiveness of Azithromycin and Doxycycline

  • A multicenter observational study found that the effectiveness of doxycycline is high and exceeds that of azithromycin for the treatment of rectal CT infections in women 4.
  • A systematic review found that in men, regimens with azithromycin are probably less effective than doxycycline for microbiological failure, but there might be little or no difference for clinical failure 5.
  • Another study found that azithromycin probably slightly reduces adverse events compared to doxycycline in men and women together, but may have little difference in men alone 5.

Ongoing Research

  • A double-blind randomised controlled trial is being conducted to compare treatment efficacy of azithromycin versus doxycycline for the treatment of rectal chlamydia in men who have sex with men 6.
  • The study aims to provide the first RCT evidence comparing azithromycin and doxycycline for the treatment of rectal chlamydia and inform international management guidelines 6.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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