Doxycycline-Treatable Infections
Doxycycline is indicated for the treatment of numerous bacterial infections including respiratory tract infections, sexually transmitted infections (particularly chlamydia, syphilis, and as an alternative for gonorrhea), rickettsial diseases, and certain skin and soft tissue infections. 1
Sexually Transmitted Infections
- Chlamydia trachomatis infections:
- Uncomplicated urethral, endocervical, or rectal infections
- Lymphogranuloma venereum
- Trachoma and inclusion conjunctivitis
- Syphilis (caused by Treponema pallidum) - when penicillin is contraindicated 1
- Nongonococcal urethritis caused by Ureaplasma urealyticum 1
- Uncomplicated gonorrhea (Neisseria gonorrhoeae) - as an alternative when penicillin is contraindicated, though resistance is increasing 2
Rickettsial Infections
- Rocky Mountain spotted fever
- Typhus fever and typhus group
- Q fever
- Rickettsialpox
- Tick fevers caused by Rickettsiae 1
Respiratory Infections
- Respiratory tract infections caused by Mycoplasma pneumoniae
- Upper respiratory infections caused by Streptococcus pneumoniae (when susceptible)
- Respiratory infections caused by Haemophilus influenzae (when susceptible) 1
Other Bacterial Infections
- Plague (Yersinia pestis)
- Tularemia (Francisella tularensis)
- Cholera (Vibrio cholerae)
- Brucellosis (Brucella species) - in conjunction with streptomycin
- Bartonellosis (Bartonella bacilliformis)
- Granuloma inguinale (Calymmatobacterium granulomatis)
- Anthrax (Bacillus anthracis) - including post-exposure prophylaxis for inhalational anthrax
- Infections caused by Clostridium species
- Listeriosis (when penicillin is contraindicated) 1
Parasitic Infections
- Malaria prophylaxis (Plasmodium falciparum) - for short-term travelers to areas with resistant strains 1
- Adjunctive therapy in acute intestinal amebiasis 1
Skin and Soft Tissue Conditions
- Severe acne - as adjunctive therapy 1
- Anti-inflammatory properties make it useful for various dermatological conditions 3
Prophylactic Uses
- Malaria prophylaxis 1
- Post-exposure prophylaxis for bacterial sexually transmitted infections (DoxyPEP) - 200mg as a single dose within 72 hours after condomless sex 4
- Lyme disease prevention 2
Important Considerations
Efficacy
- Doxycycline shows excellent tissue penetration due to its liposolubility 5
- For syphilis treatment, studies show high serological response rates: 100% for primary, 96.9% for secondary, 91.3% for early latent, and 79.2% for late latent syphilis 6
Antimicrobial Resistance
- Many strains of gram-negative microorganisms have shown resistance to doxycycline, necessitating culture and susceptibility testing 1
- Not currently recommended as first-line treatment for gonorrhea due to elevated resistance, though it remains effective against many U.S. strains 2
Administration
- Can be administered orally once or twice daily due to its long elimination half-life 5
- Typically dosed at 100mg twice daily for most infections 1
- For DoxyPEP: 200mg as a single dose within 72 hours after potential exposure 4
Contraindications and Side Effects
- Common adverse effects include photosensitivity and gastrointestinal symptoms
- Esophageal erosion and ulceration may occur 2
- Should be taken with food and plenty of fluid
- Patient should remain upright for at least 1 hour after taking
- Should be separated from dairy products, antacids, and supplements containing calcium, iron, magnesium, or sodium bicarbonate by at least 2 hours 4
Doxycycline's broad-spectrum activity, good oral bioavailability, and relatively low cost make it a valuable antibiotic option for numerous infections when used appropriately based on local resistance patterns.