Duration of Doxycycline for Cat Scratch Disease
For cat scratch disease (CSD), doxycycline is NOT the first-line antibiotic—azithromycin is preferred—but when doxycycline is used, treat for 10-14 days. 1
First-Line Treatment: Azithromycin, Not Doxycycline
The Infectious Diseases Society of America clearly recommends azithromycin as the treatment of choice for cat scratch disease, not doxycycline 1, 2. The dosing is:
- Adults and patients >45 kg: 500 mg on day 1, then 250 mg daily for 4 additional days (total 5 days) 1, 2
- Children <45 kg: 10 mg/kg on day 1, then 5 mg/kg daily for 4 additional days 1, 2
When Doxycycline Is Used for Cat Scratch Disease
While doxycycline is not the preferred agent for typical CSD, it may be used in specific circumstances:
Duration: 10-14 Days
- When doxycycline is selected for cat scratch disease, treat for 10-14 days 1
- This duration is recommended particularly for stellate neuroretinitis (a complication of CSD), where doxycycline is specifically advocated 3
Dosing
- Adults: 100 mg twice daily (oral or IV) 4, 1
- Children <45 kg: 2.2 mg/kg twice daily (oral or IV), maximum 100 mg per dose 4
Important Clinical Context
Why Azithromycin Over Doxycycline?
The evidence base for azithromycin in CSD is stronger than for doxycycline 1, 2. Historical studies showed variable efficacy with different antibiotics, with rifampin (87%), ciprofloxacin (84%), and gentamicin (73%) showing better results than many other agents 5. Doxycycline has been recommended primarily for specific complications like neuroretinitis 3.
When to Consider Treatment at All
- Most CSD is self-limited and resolves within 1-6 months without antibiotics 2, 6
- Treat when: severe symptoms, immunocompromised patients, extranodal disease (occurs in ≤2% of cases), or complications like encephalopathy, retinitis, or hepatosplenic involvement 2, 6
Critical Distinction: Infected Cat Scratch vs. Cat Scratch Disease
Do not confuse these two entities:
- Infected cat scratch wound (bacterial superinfection): Use amoxicillin-clavulanate as first-line, or doxycycline 100 mg twice daily for penicillin allergy 1
- Cat scratch disease (Bartonella henselae infection with lymphadenopathy): Use azithromycin as first-line 1, 2
Common Pitfalls to Avoid
- Do not use doxycycline monotherapy for an infected cat scratch wound if Pasteurella coverage is needed—it has good activity against Pasteurella but amoxicillin-clavulanate remains superior 1
- Do not incise and drain lymph nodes in CSD, even when suppurative (occurs in ~10% of cases) 7
- Do not confuse the 5-7 day duration for tickborne rickettsial diseases (which also use doxycycline) with the 10-14 day duration needed for CSD 4