What is the recommended prophylaxis (preventive treatment) for tick bites to prevent Lyme disease?

Tick Bite Prophylaxis for Lyme Disease Prevention

A single dose of doxycycline (200 mg for adults or 4 mg/kg up to 200 mg for children ≥8 years) is recommended for prophylaxis after a tick bite ONLY when specific high-risk criteria are met. 1

Prophylaxis Criteria

Prophylactic treatment should be administered only when ALL of the following conditions are met:

1. The tick can be reliably identified as an adult or nymphal Ixodes scapularis (deer tick) or I. pacificus
2. The tick is estimated to have been attached for ≥36 hours (based on engorgement or known time of exposure)
3. Prophylaxis can be started within 72 hours of tick removal
4. The local rate of Borrelia burgdorferi infection in ticks is ≥20% (parts of New England, mid-Atlantic states, Minnesota, Wisconsin)
5. Doxycycline is not contraindicated 2, 1

Effectiveness and Evidence

Single-dose doxycycline prophylaxis has been shown to be 87% effective in preventing Lyme disease when administered according to the above criteria 1. A 2021 European study demonstrated a 67% relative risk reduction with a number-needed-to-treat of 51 3. The protective window is narrow—animal studies suggest prophylaxis becomes ineffective when delayed beyond 48 hours after tick removal 4.

Contraindications and Special Populations

• Contraindicated in:

  • Pregnant women
  • Children <8 years of age
  • Patients with doxycycline allergy 2, 1

• Important note: Amoxicillin is NOT recommended as prophylaxis for those who cannot take doxycycline. The guidelines specifically state that amoxicillin should not be substituted for doxycycline in prophylaxis 2.

When Prophylaxis is NOT Recommended

Routine prophylaxis or serologic testing is NOT recommended for all tick bites 2. If the criteria for prophylaxis are not met, a "wait and watch" approach is recommended, with monitoring for 30 days for symptoms of tick-borne illness 1.

Prevention Measures

If tick exposure is unavoidable, the following preventive measures are recommended:

• Use protective clothing
• Apply EPA-registered tick repellents
• Check entire body for ticks daily
• Remove attached ticks promptly 2, 1

Common Pitfalls to Avoid

1. Overuse of prophylaxis: Administering prophylaxis when criteria are not met exposes patients to unnecessary antibiotics
2. Delayed administration: Prophylaxis becomes ineffective when given >72 hours after tick removal
3. Incorrect identification: Treating bites from non-Ixodes ticks (such as Lone Star ticks) with prophylaxis is not supported by evidence
4. Substituting other antibiotics: Using amoxicillin instead of doxycycline for prophylaxis is not recommended 2, 1
5. Ignoring geographic considerations: Prophylaxis is only recommended in areas with ≥20% tick infection rates 2

Recent evidence suggests that Lyme disease prophylaxis may be underprescribed for certain groups, particularly children 5, despite children being disproportionately affected by Lyme disease.