What is the dosing for post-exposure prophylaxis (PEP) with doxycycline (Vibramycin)?

Doxycycline Post-Exposure Prophylaxis (PEP) Dosing

The recommended dose for doxycycline post-exposure prophylaxis (doxy PEP) is 200 mg as a single dose taken within 72 hours after sexual exposure, with a maximum of 200 mg per 24-hour period. 1, 2

Administration Guidelines

• Doxycycline should be taken:

  • Within 72 hours after having oral, vaginal, or anal sex
  • With food or milk and a full glass of water
  • While remaining upright for at least 1 hour after taking to prevent esophageal irritation 2

• Separate doxycycline by at least 2 hours from:

  • Dairy products
  • Antacids
  • Supplements containing calcium, iron, magnesium, or sodium bicarbonate 2

Prescription Considerations

• The prescription quantity should account for enough doses based on the person's anticipated sexual activity until their next follow-up visit 2
• Doxy PEP is currently recommended primarily for:
  • Men who have sex with men (MSM)
  • Transgender women (TGW)
  • Individuals who have had at least one bacterial STI diagnosed in the past 12 months 1, 2

Monitoring and Follow-up

• Baseline STI testing is recommended at initiation of doxy PEP
• Regular STI screening should be performed every 3-6 months at anatomic sites of exposure 1, 2
• The ongoing need for doxy PEP should be reassessed every 3-6 months 1, 2
• HIV screening should be performed according to current recommendations (every 3-6 months for HIV-negative individuals) 2

Efficacy and Clinical Context

• Doxy PEP reduces:

  • Syphilis and chlamydia infections by >70%
  • Gonococcal infections by approximately 50% in high-risk populations 2, 3

• The most recent evidence confirms sustained effectiveness over 96 weeks, particularly for chlamydia and syphilis, with smaller effects for gonorrhea 3

Important Caveats

• Doxy PEP should be implemented as part of a comprehensive sexual health approach, including risk reduction counseling, STI screening, and appropriate vaccinations 1, 2
• Do not exceed 200 mg per 24-hour period for STI PEP 1, 2
• Doxy PEP is distinct from pre-exposure prophylaxis (PrEP), which involves taking medication before exposure 1
• The standard doxy PEP dose (200 mg) differs from typical treatment doses for established STIs, which are often 100 mg twice daily for 7-14 days 4
• Potential side effects include photosensitivity, esophagitis, and gastrointestinal intolerance 1, 2

Prescribing Strategy Considerations

• The most efficient prescribing strategies target individuals with a history of STIs, particularly those with concurrent or repeated STIs 5
• Prescribing to PrEP users or people living with HIV may also be an effective strategy 5, 6