Antibiotic Recommendations for Tick Bites
A single dose of doxycycline (200 mg for adults or 4 mg/kg up to 200 mg for children ≥8 years) is the only recommended antibiotic prophylaxis for tick bites, and should only be given when specific high-risk criteria are met. 1
When to Use Antibiotic Prophylaxis
Prophylactic antibiotics are not routinely recommended after all tick bites. The Infectious Diseases Society of America (IDSA) recommends limited prophylaxis due to the low risk of developing Lyme disease after a recognized tick bite (only 1-3.2% without prophylaxis) 1.
High-Risk Criteria (ALL must be met):
- Tick is identified as adult or nymphal Ixodes scapularis (deer tick) or I. pacificus
- Tick was attached for ≥36 hours
- Prophylaxis can be started within 72 hours of tick removal
- Local rate of Borrelia burgdorferi infection in ticks is ≥20% (highly endemic area) 1
Contraindications to Doxycycline Prophylaxis:
- Pregnant women
- Children <8 years of age
- Tick identified as non-Ixodes species
- Tick attached <36 hours
72 hours since tick removal
- Low-endemic areas (<20% tick infection rates) 1
Antibiotic Options
First-Line Prophylaxis:
- Single dose of doxycycline:
- Adults: 200 mg once
- Children ≥8 years: 4 mg/kg (up to 200 mg) once 1
Important Note:
- Amoxicillin is NOT recommended as prophylaxis for those who cannot take doxycycline 1
- For pregnant women or children <8 years who meet high-risk criteria, "wait and watch" is the recommended approach 1
Treatment for Established Lyme Disease
If a patient develops symptoms of Lyme disease after a tick bite, treatment recommendations differ from prophylaxis:
Early Localized Disease (Erythema Migrans):
- First-line: Doxycycline 100 mg twice daily for 10 days 1
- Alternatives:
- Amoxicillin (for children <8 years or pregnant women)
- Cefuroxime axetil 1
Other Tick-Borne Illnesses:
- For Southern Tick-Associated Rash Illness (STARI): Doxycycline 100 mg twice daily for 10 days 1
- For other tick-borne illnesses: Doxycycline 100 mg twice daily for 7-14 days (continue at least 3 days after fever subsides) 1
Monitoring After Tick Bite
- Monitor for 30 days for symptoms of tick-borne illness if prophylaxis is not given 1
- Watch for development of erythema migrans rash (typically appears 7-14 days after tick detachment)
- Erythema migrans is diagnostic of early Lyme disease without laboratory confirmation when ≥5 cm in diameter 1
Effectiveness of Prophylaxis
Single-dose doxycycline prophylaxis has been shown to be 87% effective in preventing Lyme disease when administered within the appropriate timeframe 1. Recent European research confirms this efficacy, with a 67% relative risk reduction and a number-needed-to-treat of 51 2.
Common Pitfalls to Avoid
Overprescribing antibiotics: Not all tick bites require prophylaxis. Research suggests prophylaxis may be underprescribed for some groups, including children 3, but this doesn't justify universal prophylaxis.
Using amoxicillin for prophylaxis: Unlike treatment regimens, amoxicillin is not recommended as prophylaxis for those who cannot take doxycycline 1.
Delayed administration: Prophylaxis must be started within 72 hours of tick removal to be effective 1.
Ignoring tick species and attachment time: Only certain tick species (Ixodes) attached for ≥36 hours warrant consideration for prophylaxis 1.
Extended antibiotic courses: For prophylaxis, only a single dose of doxycycline is recommended, not extended courses 1, 4.