Doxycycline Prophylactic Dosing

STI Post-Exposure Prophylaxis (Doxy PEP)

The Centers for Disease Control and Prevention recommends doxycycline 200 mg as a single dose to be taken as soon as possible within 72 hours after oral, vaginal, or anal sex for prevention of bacterial sexually transmitted infections, with a maximum of 200 mg per 24-hour period 1, 2
This regimen is specifically recommended for men who have sex with men and transgender women with at least one bacterial STI diagnosed in the past 12 months 1, 2
The prescription should account for enough doses based on anticipated sexual activity until the next visit 1, 2
Reassess ongoing need for doxy PEP every 3-6 months 1, 2

The Centers for Disease Control and Prevention recommends doxycycline 100 mg orally once daily for malaria prevention 3
Begin prophylaxis 1-2 days before travel to malarious areas 3
Continue daily during travel in malarious areas 3
Continue for 4 weeks after leaving the malarious area 3

The American Academy of Family Physicians recommends doxycycline 100 mg orally twice daily for 60 days for inhalational anthrax exposure 4
For children weighing less than 100 lb, prescribe 2.2 mg/kg orally twice daily for 60 days 4
For children weighing 100 lb or more, use adult dose of 100 mg twice daily 4

Patients must take doxycycline with a full glass of water on a full stomach with non-dairy food and remain upright for at least 1 hour after administration to prevent esophagitis 5, 6, 7
Separate doxycycline from all dairy products by at least 2 hours before AND after taking the medication to prevent chelation and reduced absorption 5, 7
Counsel patients on photosensitivity risk and recommend sun protection measures 1, 2

For STI prophylaxis, patients should not exceed 200 mg per 24 hours even with multiple sexual encounters 1, 2
Suboptimal drug levels from dairy interaction can lead to treatment failure and antimicrobial resistance development 5, 7

Doxycycline is effective against intracellular organisms, including Rickettsia species, Borrelia burgdorferi (Lyme disease), Ehrlichia/Anaplasma phagocytophilum, and Coxiella burnetii 8

For human granulocytic anaplasmosis (HGA), the recommended dose is 100 mg orally or IV twice daily for 10 days in adults, and 4 mg/kg/day divided twice daily (max 100 mg/dose) in children ≥8 years 8
For Lyme disease (early localized), the recommended dose is 100 mg orally twice daily for 10-21 days 8

For animal/human bites, doxycycline provides excellent coverage against Pasteurella multocida and Eikenella corrodens at a dose of 100 mg orally twice daily for 7-10 days 9

For STI post-exposure prophylaxis (Doxy PEP), the Centers for Disease Control and Prevention recommends a single 200 mg dose within 72 hours after condomless oral, vaginal, or anal sex (maximum 200 mg per 24 hours) 10

The Centers for Disease Control and Prevention recommends taking doxycycline with a full glass of water (≥200 mL) on a full stomach with non-dairy food, and remaining upright for at least 1 hour to prevent esophageal ulceration 10
It is recommended to separate doxycycline from dairy products, antacids, calcium, iron, magnesium, or sodium bicarbonate by at least 2 hours before AND after dosing to prevent chelation and treatment failure 10

The Centers for Disease Control and Prevention advises against exceeding 200 mg doxycycline in 24 hours for STI prophylaxis, even with multiple sexual encounters, and recommends avoiding use in children <8 years except for life-threatening infections (HGA, anthrax) due to dental staining risk 8
The Centers for Disease Control and Prevention recommends counseling patients on photosensitivity, esophagitis/esophageal ulceration, and gastrointestinal intolerance, and reviewing all medications for interactions 10