DoxyPEP Dosing and Administration
For eligible adults without contraindications, prescribe doxycycline 200 mg (any formulation) to be taken as a single dose within 72 hours after oral, vaginal, or anal sex, with a maximum of 200 mg per 24-hour period. 1
Core Dosing Protocol
The dosing is straightforward and event-driven:
- Dose: 200 mg doxycycline (any formulation)
- Timing: Take as soon as possible after sex, but no later than 72 hours post-exposure
- Frequency limit: Maximum 200 mg per 24 hours (do not exceed this even with multiple sexual encounters) 1
- Administration: Self-administered by the patient based on their sexual activity
Critical Administration Instructions
To minimize side effects, patients must follow these specific guidelines:
- Take with food: Consume on a full stomach with a full glass of liquid to reduce GI intolerance 1
- Stay upright: Avoid lying down for 1 hour after taking doxycycline to prevent esophagitis 1
- Separate from interactions: Space doxycycline at least 2 hours away from dairy products, antacids, and supplements containing calcium, iron, magnesium, or sodium bicarbonate 1
Prescribing Strategy
Write prescriptions based on anticipated sexual activity:
- Provide enough doses to last until the next follow-up visit (typically 3-6 months)
- Use shared decision-making to estimate the patient's sexual frequency
- Reassess ongoing need every 3-6 months 1
Who Should Receive DoxyPEP
Primary candidates (CDC strong recommendation, AI evidence):
- Gay, bisexual, and other men who have sex with men (MSM)
- Transgender women (TGW)
- With at least one bacterial STI (syphilis, chlamydia, or gonorrhea) in the past 12 months 1
Secondary consideration (clinical judgment):
- MSM and TGW without recent STI diagnosis but engaging in high-risk sexual activities
- Use shared decision-making for this group 1
Insufficient evidence: No recommendation can be made for cisgender women, cisgender heterosexual men, transgender men, or other queer/nonbinary persons assigned female at birth 1
Required Counseling Points
Before prescribing, discuss:
Benefits: Significant reduction in syphilis, chlamydia, and to a lesser extent gonorrhea 1
Known side effects:
- Photosensitivity (sun sensitivity)
- Esophagitis and esophageal discomfort
- GI intolerance (nausea, vomiting, diarrhea) 1
Potential long-term concerns:
- Development of antimicrobial resistance in other pathogens and commensal organisms
- Changes in the microbiome with unknown long-term effects 1
Drug interactions: Review the patient's complete medication list, including over-the-counter medications. Note that gender-affirming hormonal therapy has no clinically relevant interactions with doxycycline 1
Comprehensive Sexual Health Context
DoxyPEP should never be prescribed in isolation. Implement within a full sexual health program:
At initial visit:
- Screen for gonorrhea and chlamydia at all anatomic sites of exposure (pharyngeal, rectal, urethral)
- Serologic testing for syphilis
- HIV screening per CDC guidelines
- Provide risk reduction counseling and condoms
- Link to HIV PrEP if HIV-negative, or HIV care if living with HIV 1
At follow-up visits (every 3-6 months):
- Repeat STI screening at all exposure sites
- HIV screening for those not on PrEP
- Assess for doxycycline side effects
- Reassess continued need for doxyPEP
- Provide ongoing risk reduction counseling 1
Common Pitfalls to Avoid
Exceeding maximum daily dose: Even with multiple sexual encounters in 24 hours, patients should not take more than 200 mg total 1
Taking on empty stomach: This significantly increases risk of esophagitis and GI side effects 1
Lying down immediately after: Increases esophageal irritation risk 1
Concurrent dairy/antacid use: Reduces doxycycline absorption 1
Prescribing without comprehensive STI screening: DoxyPEP is not a replacement for regular testing and treatment 1
Indefinite prescribing without reassessment: Must evaluate ongoing need every 3-6 months 1