From the Guidelines
Doxycycline can be used as a single-dose prophylaxis for Lyme disease following a tick bite in appropriate situations, with a recommended regimen of a single dose of doxycycline 200 mg orally for adults, or 4.4 mg/kg (up to a maximum dose of 200 mg) for children, given within 72 hours of tick removal 1.
Key Considerations
- The attached tick should be identified as an Ixodes scapularis (deer tick) and have been attached for at least 36 hours based on engorgement or known time of exposure.
- Prophylaxis should be started within 72 hours of tick removal.
- The local rate of infection of ticks with Borrelia burgdorferi should be at least 20%, which includes most of the northeastern, mid-Atlantic, and north-central United States.
Patient Eligibility
- Doxycycline prophylaxis is not recommended for pregnant women, children under 8 years old (due to dental staining concerns), or for people with allergies to tetracyclines.
Efficacy and Safety
- A single dose of doxycycline can prevent the establishment of Borrelia burgdorferi infection when administered early after a tick bite, before the bacteria have had time to disseminate beyond the initial bite site 1.
- The administration of a single dose of oral doxycycline within 72 hours of tick removal is recommended over observation, with a strong recommendation and moderate-quality evidence 1.
From the Research
Role of Doxycycline Prophylaxis in Preventing Lyme Disease
- Doxycycline prophylaxis has been shown to be effective in preventing Lyme disease after a tick bite, with a single 200 mg dose given within 72 hours of the bite being 87% effective 2.
- A study in the United States found that single-dose doxycycline dispensings were most common among individuals aged 65 years and older, but may be underprescribed for certain groups, including children 3.
- A systematic review and meta-analysis found that antibiotic prophylaxis, including single-dose doxycycline, can prevent Lyme disease after a tick bite, with a pooled risk ratio of 0.38 (95% CI: 0.22-0.66) 4.
- A randomized controlled trial in Europe found that a single dose of 200 mg doxycycline after an Ixodes ricinus tick bite reduced the risk of developing Lyme borreliosis by 67% (95% CI: 31-84%) 5.
- An animal model study found that prophylactic antibiotic treatment of tick bites was most effective when delivered promptly after tick removal, with a narrow window of efficacy 6.
Efficacy of Doxycycline Prophylaxis
- The efficacy of doxycycline prophylaxis in preventing Lyme disease has been demonstrated in several studies, with risk reductions ranging from 67% to 87% 4, 2, 5.
- The use of single-dose doxycycline has been shown to be effective in preventing Lyme disease, with a pooled risk ratio of 0.29 (95% CI: 0.14-0.60) 4.
- The timing of doxycycline prophylaxis is critical, with treatment being most effective when delivered promptly after tick removal 6.
Limitations and Future Directions
- While doxycycline prophylaxis has been shown to be effective in preventing Lyme disease, there are limitations to its use, including the need for prompt treatment after tick removal and the potential for underprescription in certain groups 3, 6.
- Further studies are needed to confirm the efficacy of doxycycline prophylaxis in different populations and to explore optimal treatment strategies 4, 5.